Lectures on materials science for carpenters and joiners. Work program in the subject "Materials Science" by profession: "Master of carpentry and furniture production." Classification and standardization of forest products

05.03.2020 Heaters

Ministry of Education of the Ryazan Region

Regional state budgetary education

Institution of secondary vocational education

"Kasimovsky Technical School of Water Transport"

Work program of the academic discipline

OPD.03. Materials Science

Kasimov

2013

The work program of the academic discipline was developed on the basis of the Federal State Educational Standard (hereinafter referred to as the Federal State Educational Standard) for the profession of primary vocational education (hereinafter referred to as NPO) 262023.01 “Master of carpentry and furniture production.”

APPROVED:

Director of OGBOU SPO "KTVT"

Shmelev A.V.

"__" __________ 2013

Developer:

Lartsin Alexander Nikolaevich, teacher of OGBOU NPO “KTVT”, 1st qualification category

Coordinated with the methodological commission of general education disciplines and professional modules

Minutes of MK No. _____ dated “__” ________2013.

Chairman of the commission _______ / Orlova O.V.

	PASSPORT OF THE WORKING PROGRAM OF THE EDUCATIONAL DISCIPLINE
	STRUCTURE AND CONTENT OF THE ACADEMIC DISCIPLINE
	CONDITIONS FOR IMPLEMENTING THE ACADEMIC DISCIPLINE
	CONTROL AND EVALUATION OF THE RESULTS OF MASTERING AN ACADEMIC DISCIPLINE

1. PASSPORT OF THE WORK PROGRAM OF THE ACADEMIC DISCIPLINE

"Materials Science"

1.1. SCOPE OF THE CURRICULUM

The work program of the academic discipline "Materials Science" is part of the main professional educational program in accordance with the Federal State Educational Standard for the profession NPO 262023.01 "Master of carpentry and furniture production."

The work program of the academic discipline “Materials Science” can be used in additional vocational education (in advanced training and retraining programs) and professional training of workers in the field of production of carpentry and furniture products.

1.2. THE PLACE OF DISCIPLINE IN THE STRUCTURE OF THE BASIC PROFESSIONAL EDUCATIONAL PROGRAM: DISCIPLINE IS PART OF THE GENERAL PROFESSIONAL CYCLE.

1.3. GOALS AND OBJECTIVES OF THE DISCIPLINE - REQUIREMENTS FOR THE RESULTS OF MASTERING THE DISCIPLINE:

be able to :

select and use basic structural and auxiliary materials for the manufacture of carpentry and furniture products;
determine wood species, sort wood by defects, rationally use it in the manufacture of carpentry and furniture products;
store and dry timber and lumber;
select and use wood materials (veneer, plywood, particle boards and fibreboards) for the manufacture of carpentry and furniture products;
select and use fasteners, fittings, accessories, glass products, mirrors and other auxiliary materials in work.

As a result of mastering the discipline, the student must

know :

structural and auxiliary materials for the production of joinery and furniture products;
the structure of wood and wood, its physical, chemical, and mechanical properties, the specifics of use in the production of carpentry and furniture products;
main types of wood, their characteristics, wood grades and grades, basics of forestry merchandising;
rules for storing and drying timber and lumber;
specifics and assortment of wood materials, their scope;
specifics and assortment of fasteners, fittings, fittings, glass products, mirrors, and other auxiliary materials.

1.4. NUMBER OF HOURS FOR MASTERING THE DISCIPLINE PROGRAM:

The maximum student workload is 84 hours, including:

The student’s mandatory classroom teaching load is 60 hours;

Independent work of the student - 24 hours.

2. STRUCTURE AND CONTENT OF THE SCHOOL DISCIPLINE

Scope of academic discipline and types of academic work

Type of educational work	Qty Hour.

Mandatory classroom teaching load (total)
including:
Practical lessons
Independent work of the student (total)
final examinationin the form of differentiated credit

2.2. THEMATIC PLAN AND CONTENT OF THE ACADEMIC DISCIPLINE “MATERIALS SCIENCE”

Name sections and topics	Laboratory and practical work, independent work of students	Volume hours	Mastery level

Section 1. Basic information about wood.
Topic 1.1.Structure of wood and timber

		Tree structure. Parts of a growing tree: roots, trunk, crown, their purpose
		Wood cuts: radial, tangential and transverse
		Macroscopic structure of wood. Trunk structure: bark, bast, cambium, sapwood, heartwood and pith.
		Microscopic structure of wood: wood tissues and vessels, cellular structure of wood
	Distinctive external features of radial, tangential, transverse sections. The influence of wood structure on the quality of processing.
Section 2. Properties of wood
Topic 2.1. Physical properties of wood		Properties that determine the appearance and smell of wood
		Indicators of macrostructure.
		Wood moisture content and properties associated with its changes.
		Wood Density
		Thermal, electrical.
		Practical work
		Determination of late wood content in the annual layer.
		Determination of equilibrium moisture content of wood.
Topic 2.2. Chemical properties of wood		Chemical composition of wood and bark, basic chemical reactions.
Topic 2.3. Mechanical and technological properties of wood		Mechanical properties of wood.
		Durability of wood.
		Wood hardness.
		Technological properties of wood.
		Practical work
		Determination of the type of deformation using the proposed samples.
	Independent work for students: Chemical composition of wood. Determination of macrostructure indicators Loads on wooden products and structures.
Section 3. Wood defects and their influence on the physical and mechanical properties of wood
Topic 3.1 Defects of wood
		Defects in the shape of the trunk: camber, lumpy growths, curvature.
		Defects in the structure of wood.
		Knots, their types and measurements. Cracks. Types of cracks.
		Types of wood damage.
		Cutting defects. Warping of various shapes
		Practical work
		Determination of wood defects on samples (posters). Bitches. Determination of wood defects on samples (posters). Defects in the structure of wood.
	Independent work for students: Characteristic differences between wood defects and wood defects Causes of wood processing defects, warping and the advisability of its use in certain products.
Section 4. Characteristics of main wood species and their industrial applications
Topic 4.1. Main wood species
		Basic macroscopic characteristics of wood for identifying species.
		Ring - vascular hardwoods: oak, ash, elm, elm, karach.
		Disseminated-vascular deciduous species. Foreign breeds:
		Practical work
		Identification of coniferous species by external characteristics. Identification of deciduous ring-vascular species by external characteristics. Identification of deciduous disseminated vascular species by external characteristics.
	Independent work for students: Characteristics of various types of wood based on macroscopic characteristics with justification for their use in carpentry and furniture products
Section 5. Round forest materials
Topic 5.1. Lumber and blanks
		Classification of timber, nominal sizes, gradations, allowances and tolerances; characteristics of timber.
		Practical work
		Carrying out measurement, accounting and marking of lumber and blanks.
	Independent work for students: Methods of obtaining forest products. Characteristics of round timber. Accounting, determination of volume and labeling of round timber.
Section 6. Ensuring the durability of wood.
Topic 6.1. Wood storage, drying and protection		Wood storage The importance of proper wood storage; ways to store it. Drying wood.
		Antiseptic treatment of wood. Purpose. Protective means. Antiseptic solutions. Types of antiseptic compositions: aqueous, oil, pastes. Antiseptic methods. Painting, impregnation, coating, dry antiseptic. Fire protection.
	Independent work for students: Advantages and disadvantages of wood drying methods. The need for preserving wood, preserving it and fire protection. Methods of applying antiseptic and fire retardant compounds to the surfaces of wooden parts, structures, products.
Section 7. Wood-based materials
Topic 7.1. Wood-sheet and slab materials
		Sliced and peeled veneer: methods of production, Types and application. Characteristics of veneer, its production, grades, sizes. Plywood.
		Particle boards (chipboards) and fibreboards (Fibreboard), their types, production, brands, main sheet dimensions, use in the manufacture of joinery and furniture production
		Joinery boards and panels. The concept of wood slabs and panels.
		Practical work
		Determination of the type of sheet material from samples. Studying chipboard brands
	Independent work for students: Assortment of milled wooden parts. Designs of window, balcony, door blocks, window sill boards, basic standard sizes, types of finishes. Wood-aluminum windows, their designs and applications
Section 8. Adhesives and paints and varnishes.
Topic 8.1. Adhesive compositions.
		General information about adhesives. Types, groups, classification, basic properties, characteristics of adhesives and requirements for them. The concept of the adhesive substance, solvents and auxiliary materials (substances) included in the adhesives, adhesion, viscosity, concentration of the adhesive solution, water resistance, viability, biological stability, hot and cold curing of adhesives. Appearance of adhesives.
Topic 8.2. paints and varnishes		Materials for preparing the surface of wood and wood materials for finishing: primers, putties, fillers.
		Film-forming substances and varnishes. Paints and enamels.
		Practical lessons
		Study of the main groups of adhesives. Study of materials for wood finishing.
		Study of glutin and casein glues by external characteristics Preparation of working composition of adhesives
	Independent work for students: Types, properties, storage rules, use of glue based on synthetic resins in carpentry and furniture. Adhesive films, tapes based on paper, synthetic resins and adhesives, their types, sizes, properties and applications.
Section 9. Film and sheet materials for cladding joinery
Topic 9.1. Facing materials
		Paper-based film materials (transparent and opaque). General information about the production of films from special paper.
		Polymer-based film materials. Types of film materials. Cladding sheet materials.
	Independent work for students: Production of films from special paper. Types, brands, properties, front surface of facing material, methods of fastening. Types, properties based on polymers.
Section 10. Fittings and fasteners
Topic 10.1. Metal products and furniture fittings.
		Metal fasteners. Fasteners used in carpentry, glass and furniture making; nails: (carpentry, finishing, decorative, glass).
		Furniture fittings. Purpose and types of furniture fittings and furniture fastening elements: ties, hinges. bolts. locks (mortise, mortise, overhead), holders, furniture handles, latches, brackets, products for functional equipment of cabinet furniture. Design, types of connecting products: angles, plates
		Practical work
		Study of basic metal fasteners and furniture fittings using samples.
		Differentiated credit.
		TOTAL

3. CONDITIONS FOR IMPLEMENTING THE SCHOOL DISCIPLINE

3.1. REQUIREMENTS FOR MINIMUM MATERIAL AND TECHNICAL SUPPORT

The implementation of the academic discipline requires the presence of a classroom “Materials Science”

Classroom equipment:

seating according to the number of students;
teacher's workplace;
set of educational and visual aids “Materials Science”;
standard samples of wood of various species, macro and microstructure of wood;
albums with wood defects;
samples of wood of various species;
samples of wooden products;
samples of adhesive films and tape;
samples of basic metal fasteners and furniture fittings.

Technical training aids:

computer.

3.2. INFORMATION SUPPORT FOR TRAINING.

Main literature:

Stepanov B.A. Materials science for professions related to wood processing textbook: for beginners. prof. education. – M.: Publishing Center “Academy”, 2009.-328 p.

Additional literature:

Stepanov B.A. Handbook of carpenter and joiner: textbook. guide for beginners prof. education. – M.: Publishing Center “Academy”, 2010.-304 p.
Handbook Master of carpentry and furniture production: textbook. guide for beginners prof. education. – M.: Publishing Center “Academy”, 2010.-304 p.
Klyuev G.I. Carpenter (basic level): textbook. allowance. – M.: Publishing Center “Academy”, 2007.-80 p.

4. CONTROL AND EVALUATION OF THE RESULTS OF MASTERING THE ACADEMIC DISCIPLINE

Monitoring and evaluation of the results of mastering an academic discipline is carried out by the teacher in the process of conducting practical classes and laboratory work, testing, as well as students performing individual classes, projects, and research.

Learning outcomes (mastered skills, acquired knowledge)	Forms and methods of monitoring and assessing learning outcomes
Skills:
Describe the structure of wood of various species, macro- and microstructure of wood. Determine defects in trunk shape, wood structure, chemical stains and biological damage	Practical lessons Testing
Determine the density and moisture content of wood samples and compare them with the standard	Practical lessons
Determine the mechanical properties of wood of various species using standard samples	Practical lessons
Identify wood species by external characteristics and properties
Distinguish adhesives by external characteristics and prepare a working composition of adhesives	Practical lessons Testing
Identify metal fasteners and furniture fittings based on patterns	Practical lessons
Knowledge :
about the purpose of parts of the tree; characterize wood cuts using samples, outline the distinctive external features of radial, tangential, and transverse cuts.	Practical lessons Testing
about the properties that determine the appearance of wood; types of moisture in wood	Independent work
about the mechanical and technological properties of wood	Extracurricular independent work
About methods of antiseptic wood, its conservation and fire protection	Practical lessons Testing
About the types of forest materials and lumber	Practical lessons
About the technology of production of veneer, plywood, plywood particle boards and fibreboards, their types, sizes, grades.	Extracurricular independent work
basic information about adhesives, paints and varnishes, their purpose and properties.	Practical classes, extracurricular independent work
basic information about metal products and furniture fittings	Practical lessons

Branch of the state budgetary professional

educational institution of the Yamalo-Nenets Autonomous Okrug

"Yamal Multidisciplinary College" in Labytnangi

(branch of GBPOU Yamalo-Nenets Autonomous Okrug "YaMK" in Labytnangi)

Reviewed:

MO "Builder"

protocol no. 5

Approved

Methodological advice

protocol No. __________

from _____________2015

Materials

for differentiated credit

in the academic discipline "Materials Science"

by profession 18880 “Construction carpenter”

2015

Explanatory note

The test material for differentiated assessment is compiled on the basis of the Federal State Educational Standard (FSES) for the profession SPO 18880 “Construction carpenter” and in accordance with the requirements for the knowledge and skills of students in the academic discipline “Materials Science” stated in the Work Program.

The purpose of differentiated credit– conducting final certification of students in the discipline for the course of study.

The subject of the academic discipline “Materials Science” is a system of knowledge about the rational and integrated use of wood through processing into useful and high-grade products without any losses and waste in the process of work. The current structure of wood harvesting, the increase in the cost of transportation from harvesting sites to places of consumption, make the issue of saving and rational use of wood very important.

Experience shows that in order to produce high-quality products and perform work, a joiner, carpenter, glazier, parquet worker, or woodworker require good knowledge of work technology, product design and material properties. The type and properties of the materials used determine the processing methods and modes, the quality of the manufactured products, their appearance, strength, durability and cost. The structure of technological equipment and tools, the labor intensity of the work and the duration of the production cycle, the level of possible mechanization, working conditions and the necessary qualifications of workers depend on the materials. The solution to this important task is possible only by qualified craftsmen who have all the necessary knowledge.

In market conditions, vocational education faces the urgent issue of training professional personnel who can easily adapt to changing production conditions. At the current level of construction, it is impossible to become an experienced woodworker without systematic advanced training, without studying advanced technology, types of modern materials and labor organization. The task of the SVE is to develop certain skills and abilities in the future young worker, so that he becomes an active builder, a zealous owner with the morals, interests, collectivist psychology, and high culture of work, behavior, and life inherent in the working class.

The purpose of implementing this program is to provide knowledge of the main types of wood, their properties, structural features, defects, methods of storage, drying, antiseptic and fire protection, and a number of concepts in the discipline “Materials Science”.

The course “Materials Science” includes overview topics and graphic ones, the combination of which makes it possible not only to introduce students to a number of possible concepts of wood science, but also a connection with practice.

activation of methods of mental activity: generalization, systematization, comparison;

identifying the depth of knowledge of factual material.

The test material consists of 25 test items of part A and 10 test items of part B, compiled in two versions and includes questions on the main sections of the discipline:

The structure of wood and wood.

Defects of wood.

Round timber, lumber, blanks and products.

The time to complete this test is 1 academic hour.

Evaluation criteria:

35-33 points – “5”;

32-30 points – “4”;

29-27 points – “3”;

less than 27 points - “2”.

SPO specialty: 18880 “Construction carpenter”

VD 01. Materials science

Specification of didactic units

p/p

Name of didactic units

The structure of wood and wood.

Physical properties of wood.

Mechanical properties of wood.

Defects of wood.

Characteristics of main wood species and their industrial applications.

Veneer, plywood, wood boards, parquet.

Adhesives, their types, composition and properties.

Materials for preparing the surface of joinery for finishing.

Materials and products for floors. Construction materials.

Facing, insulating and roofing materials for construction.

Codifications of test items

No.

Name of didactic unit

Option number

Question numbers

The structure of wood and wood.

1,2,3,4,5,6, 26,27,28,29

1,2,3,4,5,6, 26,27,28

Physical properties of wood.

7,8,9,10,30, 31

7,8,9,10,29

Mechanical properties of wood.

11,12

11,12,30

Defects of wood.

13,14,15,16,17,32,33,34

13,14,15,16,17,31,32,33

Characteristics of main wood species and their industrial applications.

18,19

18,19,34

Round timber, lumber, blanks and products.

20,35

Veneer, plywood, wood boards, parquet.

21,35

Adhesives, their types, composition and properties.

Materials for preparing the surface of joinery for finishing.

Materials and products for floors. Construction materials.

Facing, insulating and roofing materials for construction.

NPO specialty: 18880 "Construction carpenter"

Curriculum section: General professional cycle

VD 01. Materials science

Option #1

Block A

No.

Assignment (question)

Reference

answer

Instructions for completing tasks No. 1-25: select the letter corresponding to the correct answer and write it down on the answer form. For example:

№ tasks

Possible answer

1-B

Choose the correct answer:

A).root;

B).trunk;

B).crown;

G).komel.

Choose the correct answer:

A).cambium;

B).shell;

B).cork;

G).bast.

Choose the correct answer:

A cut running perpendicular to the transverse one through the core of the trunk?

A).transverse;

B).radial;

B).tangential;

D).longitudinal.

Choose the correct answer:

In a growing tree, acts as a conductor of water from roots to leaves?

A). resin passages;

B). cambium;

B).core;

G). sapwood.

Choose the correct answer:

A).late;

B).early;

B).summer;

D).spring.

Choose the correct answer:

Tissues that are a keeper and reservoir of nutrients?

A).mechanical;

B).integumentary;

B).support;

D).storing.

Choose the correct answer:

The pattern on the surfaces of the cuts that is obtained by cutting wood fibers, annual layers and medullary rays?

A).macrostructure;

B).texture;

B).structure;

D).drawing.

Choose the correct answer and continue the sentence:

The degree of moisture content of wood that has been in water for a long time?

A).air-dry;

B).room-dry;

B).freshly cut;

D).wet.

Choose the correct answer:

A).cracking;

B).drying;

B).swelling;

D).warping.

Choose the correct answer:

The ability of wood to directionally reflect light?

A).smell;

B).texture;

B).shine;

D).color.

Choose the correct answer:

The ability of a material to resist the penetration of solid bodies into it?

A).hardness;

B).density;

B).strength;

D).deformation.

Choose the correct answer:

The ability of wood to resist wear, i.e. destruction due to friction?

A).deformability;

B).bending ability;

B).splitting;

D).wear resistance.

Choose the correct answer:

A).commonness;

B).conciseness;

B).curvature;

D).roll.

Choose the correct answer:

A).methic;

B).shrinkage;

B).slap;

D).frosty.

Choose the correct answer:

Deep marks left on the surface of the wood by the working parts of the cutting tool?

A).scratches;

B).risks;

B).hairiness;

D).dent.

Mycelium and fruiting of mold fungi on damp sapwood, with improper storage of timber?

A).sapwood rot;

B).browning;

B).kernel rot;

D).mold.

A). wingedness;

B).warping;

G).oblique layer.

B).conifers;

D).foreign.

Does hardwood wood turn gray after being in water for a long time?

A).alder;

B).stained oak;

B).gray birch;

G).linden.

Products that result from the mechanical processing of primarily a tree trunk?

A).lumber;

B).timber;

B).blanks;

B).assortments.

A). Fiberboard;

B). chipboard;

B).plywood;

G).veneer;

Glue made from scraps of raw hides and tannery waste?

A).glutinous;

B).bone;

B).casein;

D).

Paint and varnish compositions that level the surface before applying opaque coatings?

A).pore fillers;

B).primers;

B).putties;

G).varnishes.

Roll material for flooring?

A).linoleum;

B).roofing felt;

B).glassine;

G).only.

A facing material made from gypsum binder and cardboard, intended for cladding walls and partitions?

A).laminated paper;

B).plasterboard;

B).cement particle boards;

D).laminated panels.

Block B

No.

Assignment (question)

Reference

answer

root

bast

A dark-colored part of the trunk that performs a mechanical function in a growing tree?

core

early

The pattern on the surfaces of the sections, determined by the width of the annual layer, the direction of the fibers?

texture

color

thrashing

scratches

warping

lumber

NPO specialty: 18880 "Construction carpenter"

Curriculum section: General professional cycle

OP 04. Fundamentals of Construction Economics

Option No. 2

Block A

No.

Assignment (question)

Reference

answer

Instructions for completing tasks No. 1-25: Select the letter corresponding to the correct answer and write it down on the answer form.

For example:

№ tasks

Possible answer

1-B

Choose the correct answer:

The lower part of the trunk, making up 15% of the total mass of the tree?

A).root;

B).trunk;

B).crown;

G).komel.

Choose the correct answer:

A layer of bark that conducts water with organic substances produced in leaves or needles down the trunk?

A).cambium;

B).shell;

B).cork;

G).bast.

Choose the correct answer:

A cut that extends some distance from the core?

A). transverse;

B). radial;

IN). tangential;

G). longitudinal.

Choose the correct answer:

A dark-colored part of the trunk that performs a mechanical function in a growing tree?

A).resin passages;

B).cambium;

B).core;

D).sapwood.

Choose the correct answer:

Light-colored wood produced in spring and early summer?

A).late;

B).early;

B).summer;

D).spring.

Choose the correct answer:

Tissues found in the bark that protect the wood from external influences?

A).mechanical;

B).integumentary;

B).support;

D).storing.

Choose the correct answer:

The pattern on the surfaces of the sections, determined by the width of the annual layer, the direction of the fibers, etc.?

A).macrostructure;

B).texture;

B).structure;

D).drawing.

Choose the correct answer:

The degree of moisture content of wood exposed to air for a long time?

A).air-dry;

B).room-dry;

B).freshly cut;

D).wet.

Choose the correct answer:

Reduction in linear dimensions and volume of wood when drying?

A).cracking;

B).drying;

B).swelling;

D).warping.

Choose the correct answer:

A property of wood determined by the presence of tannins, resins and dyes in it?

A).smell;

B).texture;

B).shine;

D).color.

Choose the correct answer:

The ability of a material to resist destruction from stresses arising under the influence of a load?

A).hardness;

B).density;

B).strength;

D).deformation.

Choose the correct answer:

Does wood change shape and size under loads or other factors?

A).deformability;

B).bending ability;

B).splitting;

D).wear resistance.

Choose the correct answer:

A sharp increase in the diameter of the butt part of the timber or the width of unedged lumber?

A).commonness;

B).conciseness;

B).curvature;

D).inclination of fibers.

Choose the correct answer:

Cracks in the core, passing between the annual layers and having a significant extent along the length of the timber?

A).methic;

B).shrinkage;

B).slap;

D).frosty.

Choose the correct answer:

Damage to the surface of timber with a sharp object in the form of a narrow long damage?

A).scratches;

B).risks;

B).hairiness;

D).dent.

Are branch bases encased in wood the most common wood defect?

A).cracks;

B).knots;

B).edge;

D).stepson.

Curvature of lumber during sawing, drying or storage?

A). wingedness;

B).warping;

G).oblique layer.

Wood species that have a turpentine smell and almost all of them have visible resin ducts?

A).deciduous ring-vascular;

B).deciduous disseminated vascular;

B).conifers;

D).foreign.

Hardwood that turns dark brown or black after being in water for a long time (decades)?

A).alder;

B).stained oak;

B).gray birch;

G).linden.

Materials obtained by longitudinal sawing of logs and ridges of certain sizes and quality?

A).lumber;

B).timber;

B).blanks;

B).assortments.

Sheet material made by hot pressing or drying a mass of wood fibers, formed into a carpet?

A). Fiberboard;

B). chipboard;

B).plywood;

G).veneer;

Glue containing milk protein?

A).glutinous;

B).bone;

B).casein;

D).

Compounds designed to be rubbed into wood pores to seal them before clear coats are applied?

A).pore fillers;

B).primers;

B).putties;

G).varnishes.

Type of profile moldings (vinyl lining)?

A).metal tiles;

B).siding;

B).plexiglass;

G).ondulin.

Sheet roofing material made of profiled galvanized steel?

A).shingle;

B).asbestos-cement corrugated sheets;

B).ondulin;

D).metal tiles.

Block B

No.

Assignment (question)

Reference

answer

Instructions for completing tasks No. 26-35: in the appropriate line of the answer form, write down a short answer to the question, the end of a sentence or missing words.

The upper part of the trunk, making up 12% of the total mass of the tree?

crown

A layer of bark that protects the wood of the trunk from sudden temperature changes, mechanical damage and other external influences?

suberic

Does wood facing the bark grow in late summer and early fall?

late

Increase in linear dimensions and volume of wood with increasing moisture content?

swelling

The ability of wood to resist wear, i.e. destruction due to friction?

wear resistance-bone

Change in trunk diameter along the length of the tree, a gradual decrease in the diameter of the tree from the butt to the top?

conciseness

Radially directed cracks that appear in a felled tree under the influence of internal stresses during the drying process?

shrinkage

Spiral (helical) curvature of lumber along its length?

wingedness

Tree species in which the medullary rays are not visible, and the annual layers differ in all sections?

conifers

Laminated sheet material, usually consisting of an odd number of layers?

The book provides information about the structure, physical and mechanical properties, defects of wood and their impact on its quality, provides classification and distinctive features of coniferous and deciduous wood. The classification and characteristics of round timber, lumber and blanks, planed and peeled veneer, plywood, wood boards, as well as wooden parts and products for construction are given. Polymer materials and products for flooring, adhesives, paints and varnishes and furniture fittings are described.

Introduction

Basics of wood science

1. Structure of wood and timber
Tree structure
Macroscopic structure of wood
Microscopic structure of wood

2. Physical properties of wood
Properties that determine the appearance of wood
Wood moisture content and properties associated with its change
Wood Density
Thermal conductivity, sound conductivity, electrical conductivity of wood

3. Mechanical properties of wood
General concepts about mechanical properties and testing of wood
Wood strength
Hardness, deformability and impact strength of wood
Technological properties of wood

4. Wood defects
Bitches
Cracks
Trunk shape defects
Wood structural defects
Chemical stains
Fungal lesions
Damage to wood by insects
Foreign inclusions and defects
Wood deformation

5. Characteristics of main wood species and their industrial significance
Basic macroscopic characteristics of wood for determining species
Conifers
Hardwood
Foreign tree species

Adhesives and finishing materials

6. Adhesives
Types, composition and main properties of adhesives
Animal adhesives
Casein glues
Synthetic adhesives

7. Paintwork and other finishing materials
Colorants, fillers, solvents, thinners, plasticizers
Film-forming substances
Primers, fillers, putties and putties
Varnishes and polishes
Paints and enamels

8. Film and sheet finishing materials
Film and sheet materials based on papers
Synthetic resin films
Decorative laminates

9. Auxiliary materials
Sanding materials
Polishing, de-resining and bleaching compounds

Forestry merchandising

10. Classification and standardization of forest products

11. Round timber
Characteristics of round timber
Measurement, accounting and marking of round timber
Round timber storage

12. Lumber and blanks
Characteristics of lumber
Softwood and hardwood lumber
Blanks
Measurement, accounting and marking of lumber and blanks

13. Ways to extend the life of wood
Storage and atmospheric drying of wood
Preserving wood from rotting and destruction by insects
Fire protection of wood

14. Veneer, plywood and wood boards
Sliced and peeled veneer
Regular plywood
Special purpose plywood
Plywood boards
Bent-glued blanks
Joiner boards
Fiberboards
Particle boards

15. Materials and products for construction
Window and balcony blocks
Door blocks
Flooring materials and products
Milled and molded wooden parts for construction
Roofing and other materials

16. Metal products and furniture fittings
Brief information about metals and alloys
Metal fasteners
Devices and products for windows and doors
Furniture fittings
Glass and mirrors

17. Insulating, fastening and lubricating materials
Insulating materials and mastics
Electrical insulating materials
Lubricants

Introduction 3
Section one. Fundamentals of wood science 5
Chapter I. Structure of wood and timber 5
§ 1. Tree structure 5
§ 2. Macroscopic structure of wood 6
§ 3. Microscopic structure of wood 9
Chapter II. Physical and chemical properties of wood 12
§ 4. Properties that determine the appearance of wood 12
§ 5. Wood moisture content and properties associated with its change 14
§ 6. Density of wood 17
§ 7. Thermal conductivity, sound conductivity, electrical conductivity of wood 18
§ 8. Chemical structure and use of wood 19
Chapter III. Mechanical properties of wood 20
§ 9. Strength of wood 20
§ 10. Hardness, deformability and impact strength of wood 21
§ 11. Technological properties of wood 22
Chapter IV. Wood defects 23
§ 12. Knots 23
§ 13. Cracks 26
§ 14. Defects in the shape of the trunk 28
§ 15. Defects in the structure of wood 29
§ 16. Chemical stains. . . , .... 34
§ 17. Fungal infections. , 34
§ 18. Biological damage. . . . ... . . . 36
§ 19. Foreign inclusions, mechanical damage and processing defects 37
§ 20. Warped™. . . . .. . ; . ........ . . , - . . . . 39
Chapter V. Characteristics of wood of the main raw materials and their industrial significance 40
§ 21. Basic macroscopic characteristics of wood for determining species 40
§ 22. Coniferous species 40
§ 23. Hardwood 43
§ 24. Foreign rocks 47
Section two. Forestry merchandising 48
Chapter VI. Classification and standardization of forest products 48
§ 25. Classification of forest products 48
§ 26. Characteristics of round timber 49
§ 27. Measurement, accounting and marking of round timber 51
§ 28. Storage of round timber 52
Chapter VII. Lumber and blanks 53
§ 29. Characteristics of lumber 53
§ 30. Lumber of softwood and hardwood 55
§ 31. Blanks 57
§ 32. Measurement, accounting and marking of lumber and blanks 62
Chapter VIII. Methods for storing and extending the service life of wood 62
§ 33. Storage and atmospheric drying of wood 63
§ 34. Preservation of wood from rotting and destruction by insects 64
§ 35. Fire protection of wood 65
Chapter IX. Veneer, plywood, wood boards and plastics 66
§ 36. Planed and peeled veneer 66
§ 37. Plywood 67
§ 38. Special purpose plywood 68
§ 39. Plywood boards 70
§ 40. Wood panels 71
§ 41. Fiberboards 72
§ 42. Particle boards 73
143

Section three. Adhesives and finishing materials 75
Chapter X. Adhesives 75
§ 43. Types, composition and main properties of adhesives 75
§ 44. Glutin adhesives "77
§ 45. Casein adhesives 78
§ 46. Synthetic adhesives 79
Chapter XI. Materials for preparing the surface of joinery for finishing 8-5
§ 47. Grinding (abrasive) materials 85
§ 48. Primers, fillers, putties and putties 88
§ 49. Removal and bleaching compounds 91
Chapter XII. Paint and varnish materials 91
§ 50. Dyes, fillers, solvents, thinners, plasticizers... 92
§ 51. Film-forming substances 94
§ 52. Varnishes and polishes 96
§ 53. Paints and enamels 99
§ 54. Refinement of paint and varnish coatings 102
Chapter XIII. Film and sheet finishing materials 104
§ 55. Film and sheet materials based on papers 104
§ 56. Films made of synthetic resins 105
§ 57. Decorative laminates 105
Section four. Materials and products for construction 107
Chapter XIV. Materials and products for floors 107
§ 58. Parquet, parquet boards and panels 107
§59. Polymer materials for floors
§ 60. Mastics P2
Chapter XV. Structural, facing and roofing materials for construction. . . 114
§61. Construction materials and parts 114
§ 62. Roofing materials 118
§ 63. Facing materials. 123
Chapter XVI. Metal products and furniture fittings 126
§ 64. Metal fasteners 126
§ 65. Devices and products for windows and doors 127
§ 66. Furniture fittings 131
§ 67. Glass and mirrors 136
Chapter XVII. Insulating and lubricants 138
§ 68. Insulating materials 138
§ 69. Electrical insulating materials 139
§ 70. Lubricants 140
List of recommended literature 142

Introduction 3
BASICS OF TIMBER 4
1. Structure of wood and timber 4
§ 1. Tree structure 4
§ 2. Macroscopic structure of wood 6
§ 3. Microscopic structure of wood 10

2. Physical properties of wood 14
§ 5. Wood moisture content and properties associated with its change 16
§ 6. Density of wood
§ 7. Thermal conductivity, sound conductivity, electrical conductivity of wood 21

3. Mechanical properties of wood
§ 8. General concepts about mechanical properties and testing of wood 21
§ 9. Strength of wood
§ 10. Hardness, deformability and impact strength of wood 23
§ 11. Technological properties of wood 24

4. Wood defects 25
§ 12. Knots 26
§ 13. Cracks 29
§ 14. Defects in the shape of the trunk 32
§ 15. Defects in the structure of wood 33
§ 16. Chemical colors 39
§ 17. Fungal infections 39
§ 18. Damage to wood by insects 43
§ 19. Foreign inclusions and defects 44
§ 20. Wood deformations 46

5. Characteristics of main wood species and their industrial significance 46
§ 21. Basic macroscopic characteristics of wood for determining species 46
§ 22. Coniferous species 47
§ 23. Hardwood 49
§ 24. Foreign tree species 55

ADHESIVES AND FINISHING MATERIALS 57

6. Adhesives 57
§ 25. Types, composition and basic properties of adhesives 57
§ 26. Adhesives of animal origin 59
§ 27. Casein adhesives 62
§ 28. Synthetic adhesives 63

7. Paintwork and other finishing materials
§ 29. Dyes, fillers, solvents, thinners, plasticizers 68
§ 30. Film-forming substances 71
§ 31. Primers, fillers, putties and putties 73
§ 32. Varnishes and polishes 76
§ 33. Paints and enamels 81

8 Film and sheet finishing materials 8E
§ 34. Film and sheet materials based on papers 85
§ 35. Films made of synthetic resins 86
§ 36. Decorative laminates 87

9. Auxiliary materials 88
§ 37. Grinding materials
§ 38. Polishing, de-resining and bleaching compounds 90

FOREST COMMODITY 93

10. Classification and standardization of forest products 93
11. Round timber 94
§ 39. Characteristics of round timber 94
§ 40. Measurement, accounting and marking of round timber 96
§ 41. Storage of round timber 99

12. Lumber and blanks 99
§ 42. Characteristics of lumber 99
§ 43. Lumber of softwood and hardwood 102
§ 44. Blanks § 45. Measurement, accounting and marking of lumber and blanks 105

13. Ways to extend the service life of wood 107
§ 46. Storage and atmospheric drying of wood
§ 47. Preservation of wood from rotting and destruction by insects 109
§ 48. Fire protection of wood 112

14. Veneer, plywood and wood boards 113
§ 49. Planed and peeled veneer IZ
§ 50. Regular plywood 115
§ 51. Special purpose plywood 116
§ 52. Plywood boards 118
§ 53. Bent-glued blanks 118
§ 54. Wood panels
§ 55. Fiberboards 120
§ 56. Particle boards 123

15. Materials and products for construction 125
§ 57 Window and balcony blocks 125
§ 58 Door blocks 129
§ 59. Materials and products for floors 132
§ 60. Milled and molded wooden parts for construction 139
§ 61. Roofing and other materials 143

16. Metal products and furniture fittings 147
§ 62. Brief information about metals and alloys 147
§ 63. Metal fasteners 150
§ 64. Devices and products for windows and doors 152
§ 65. Furniture fittings 157
§ 66. Glass and mirrors 164

17. Insulating, fastening and lubricating materials 166
§ 67. Insulating materials and mastics 166
§ 68. Electrical insulating materials 168
§ 69. Lubricants 169
Literature 170

The book provides information about the structure, physical and mechanical properties, defects of wood and their impact on its quality, provides classification and distinctive features of coniferous and deciduous wood. The classification and characteristics of round timber, lumber and blanks, sliced and peeled veneer, plywood, wood boards, as well as wooden parts and products for construction are given.

Introduction

It is difficult to name any branch of the national economy where wood is not used in one form or another (natural or processed), and to list all the various products in which wood is an integral part. In terms of volume of use and variety of applications in the national economy, no other material can compare with wood.
The widespread use of wood is facilitated by its high physical and mechanical qualities, good workability, as well as effective ways to change individual properties of wood through chemical and mechanical processing. Wood is easy to process, has low thermal conductivity, fairly high strength, good resistance to shock and vibration loads, and is durable in a dry environment. The positive properties of wood are the ability to bond firmly, maintain a beautiful appearance and accept finishing well. At the same time, wood has disadvantages: it is susceptible to burning and rotting, is destroyed by insects and fungi, and is hygroscopic, as a result of which it can swell and be subject to shrinkage, warping and cracking. In addition, wood has defects of biological origin that reduce its quality.
In the manufacture of wood products, adhesives, paints and varnishes, finishing films, plastics, fittings and other materials play an important role.
Peeled and planed veneers are widely used in the manufacture of joinery - the starting materials for the production of various semi-finished products. Peeled veneer is used to make laminated wood - plywood, plywood boards, laminated furniture parts, parts of TV and radio cases, containers. Sliced veneer is the main facing material for parts made from low-value wood, plywood and particle boards.
The type and properties of the materials used determine the processing methods and modes, the quality of the products produced, their appearance, strength, durability, and cost.
Unlike oil, coal and gas, wood is a renewable natural resource. However, this does not exclude the need for careful and rational use. Achievements of science, especially chemistry, and advanced experience are the basis for the use of wood - this gift of living nature. Rational use of forests is an important part of the general problem of nature conservation, the national importance of which was emphasized in the Resolution of the Supreme Soviet of the USSR of September 20, 1972 “On measures to further improve nature conservation and rational use of natural resources.” Article 67 of the Constitution (Basic Law) of the Union of Soviet Socialist Republics states: “Citizens of the USSR are obliged to take care of nature and protect its wealth.” The protection of forest resources is easy to explain: forests have a beneficial effect on the country's climate, create good working and leisure conditions for people, and for the development of agriculture. Massive deforestation leads to the formation of deserts, soil erosion, shallowing of rivers, the occurrence of dry winds and a sharp decrease in crop yields. Forest is our national wealth, it must be used carefully, with the greatest return. In the tenth five-year plan, due to deepening the processing of raw materials, expanding the technological use of waste and low-quality wood, the saving of industrial wood should amount to more than 40 million m3. To make a feasible contribution to the implementation of this important national economic task is a matter of honor for every joiner and carpenter, every logger and woodworker.

BASICS OF TIMBER SCIENCE
1. Structure of wood and timber
§ 1. Tree structure
Parts of a growing tree. A growing tree consists of a crown, trunk and roots (Fig. 1). During the life of the tree, each of these parts performs its own specific functions and has different industrial applications.
The crown consists of branches and leaves (or needles). From carbon dioxide absorbed from the air and water obtained from the soil, complex organic substances necessary for the life of the tree are formed in the leaves. The industrial use of the crown is small. From the leaves (needles) vitamin flour is obtained - a valuable product for livestock and poultry farming, medicines, from the branches - technological mixture for the production of container board and fiberboards.
The trunk of a growing tree conducts water with dissolved minerals upward (upward current), and with organic matter down to the roots (downward current); stores reserve nutrients; serves to place and maintain the crown. It provides the bulk of wood (from 50 to 90% of the volume of the entire tree) and is of major industrial importance. The upper thin part of the trunk is called the top, the lower thick part is called the butt.
In Fig. Figure 1, b shows the process of development of a coniferous tree from a seed and a diagram of the construction of a tree trunk at the age of 13 years. The growth process can be thought of as the growth of cone-shaped layers of wood. Each last cone has a greater height and base diameter. The figure shows 10 concentric circles (the boundaries of annual growth) on the lower cross-section, and on the upper cross-section there are only five of them. Therefore, it takes 3 years and 8 years respectively for the tree to reach the height at which the lower and upper transverse cuts are made.
The roots carry water with minerals dissolved in it up the trunk; store nutrients and keep the tree upright. The roots are used as secondary fuel. Some time after felling the trees, stumps and large pine roots serve as raw materials for the production of rosin and turpentine.
Main sections of the trunk. A cut passing perpendicular to the axis of the trunk forms an end plane, a cut passing through the core of the trunk forms a radial plane, and at some distance from it a tangential plane (Fig. 2). The wood in these cuts has a different appearance and different properties.
On the cross section of the trunk (Fig. 3) you can see the pith, bark and wood with its annual layers.
The bark covers the tree with a continuous ring and consists of a layer - the crust and an inner layer - the bast 5, which conducts water with organic substances produced in the leaves down the trunk. The bark protects the tree from mechanical damage, sudden changes in temperature, insects and other harmful environmental influences.
The type and color of the bark depend on the age and type of tree. Young trees have smooth bark, but with age, cracks appear in the bark. The bark can be smooth (fir), scaly (pine), fibrous (juniper), warty (euonymus). The color of the bark has many shades, for example, white for birch, dark gray for oak, dark brown for spruce.
Rice. 3. Cross section of the trunk:
7 - core 2 - core rays 3 - core. 4 - cork xu, 5 - bast layer 6 - sapwood. 7 - cambium. 8 - annual layers
Depending on the species, age of the tree and growing conditions in our forest species, the bark makes up from 6 to 25% of the volume of the trunk. The bark of many tree species has many practical uses. It is used for tanning leather, making floats, stoppers, thermal insulation and building boards. Bast, matting, ropes, etc. are made from the bast bark. Chemicals used in medicine are extracted from the bark. Birch bark serves as a raw material for producing tar. Between the bark and the wood there is a very thin, juicy layer invisible to the naked eye - the cambium, consisting of living cells.
Wood in a growing tree occupies most of the trunk and is of primary industrial importance.
Terms and definitions of basic concepts related to the structure and physical and mechanical properties of wood are established by GOST 23431-79.
§ 2. Macroscopic structure of wood
Sapwood, heartwood, mature wood
The wood of our forest species is usually painted in a light color. Moreover, in some species the entire mass of wood is painted in one color (alder, birch, hornbeam), while in others the central part has a darker color (oak, larch, pine). The dark-colored part of the trunk is called the core, and the light-colored peripheral part is called sapwood.
In the case when the central part of the trunk has a lower water content, i.e., is drier, it is called mature wood, and the species are called mature wood. Rocks that have a core are called sound rocks. The remaining species, which have no difference between the central and peripheral parts of the trunk either in color or in water content, are called sapwood (non-core).
Of the tree species growing on the territory of the Soviet Union, the core is: coniferous - pine, larch, cedar; deciduous - oak, ash, elm, poplar. Mature wood species include coniferous spruce and fir, and deciduous beech and aspen. Sapwood species include deciduous trees: birch, maple, hornbeam, boxwood.
However, in some non-core species (birch, beech, aspen), darkening of the central part of the trunk is observed. In this case, the dark central zone is called the false nucleus.
Young trees of all species do not have a core and consist of sapwood. Only over time does the core form due to the transition of sapwood into sound wood.
The core is formed due to the death of living wood cells, blockage of water supply pathways, deposition of tannins, dyes, resin, and calcium carbonate. As a result, the color of the wood, its weight and mechanical properties change. The width of the sapwood varies depending on the species and growing conditions. In some species, the core is formed in the third year (yew, white acacia), in others - in the 30-35th year (pine). Therefore, the sapwood of gis is narrow, while that of pine is wide.
The transition from sapwood to heartwood can be sharp (larch, yew) or smooth (walnut, cedar). In a growing tree, the sapwood serves to conduct water and minerals from the roots to the leaves, and the core performs a mechanical function. Sapwood easily allows water to pass through and is less resistant to decay, so when making containers for liquid goods, sapwood should be used sparingly.
Annual layers, early and late wood
A cross section shows concentric layers located around the core. These formations represent the annual growth of wood. They are called annual layers. On a radial section, the annual layers look like longitudinal stripes, on a tangential section, they look like sinuous lines (Fig. 4). The annual layers grow annually from the center to the periphery and the youngest layer is the outer one. By the number of annual layers on the end section on the butt, you can determine the age of the tree.
The width of the annual layers depends on the breed, growth conditions, and position in the trunk. In some species (fast-growing), the annual layers are wide (poplar, willow), in others they are narrow (boxwood, yew). The narrowest annual layers are located in the lower part of the trunk; upward along the trunk, the width of the layers increases, since the tree grows both in thickness and in height, which brings the shape of the trunk closer to a cylinder.
For the same breed, the width of the annual layers can be different. Under unfavorable growth conditions (drought, frost, lack of nutrients, waterlogged soils), narrow annual layers are formed.
Sometimes on two opposite sides of the trunk the annual layers have unequal width. For example, in trees growing on the edge of a forest, on the side facing the light, the annual layers are larger. As a result, the core of such trees is shifted to the side and the trunk has an eccentric structure.
Some rocks are characterized by an irregular shape of the annual layers. Thus, on a cross section of hornbeam, yew, and juniper, wavy annual layers are observed.
Each annual layer consists of two parts - early and late wood: early wood (inner) faces the core, light and soft; late wood (outer) faces the bark, dark and hard. The distinction between early and late wood is clearly expressed in conifers and some leaves.
Rice. S. View of the core rays on transverse (a), tangential (b), radial (c) sections of wood
vein breeds. Early wood is formed in early summer and serves to conduct water up the trunk; Late wood is deposited towards the end of summer and serves mainly a mechanical function. Its density and mechanical properties depend on the amount of late wood.
Core rays, core repeats
In a cross section of some rocks, light, often shiny, lines directed from the pith to the bark - pith rays - are clearly visible to the naked eye (Fig. 5). All breeds have medullary rays, but are visible only in some.
The width of the medullary rays can be very narrow, invisible to the naked eye (in boxwood, birch, aspen, pear and all conifers); narrow, difficult to distinguish (in maple, elm, elm, linden); wide, clearly visible to the naked eye in cross section. Wide rays can be truly wide (in oak, beech) and falsely wide - bunches of closely spaced narrow rays (in hornbeam, alder, hazel).
On a radial section, the medullary rays are visible in the form of light shiny stripes or ribbons located across the fibers. The core rays may be lighter or darker in color than the surrounding wood.
On a tangential section, they are visible in the form of dark strokes with pointed ends or in the form of lenticular strips located along the fibers." The width of the rays ranges from 0.015 to 0.6 mm.
The core rays in felled wood create a beautiful pattern (on a radial section), which is important when choosing wood as a decorative material.
In a growing tree, the pith rays serve to conduct water horizontally and store reserve nutrients.
The number of medullary rays depends on the species: deciduous species have approximately 2-3 times more medullary rays than conifers.
On the end section of wood of some species, you can see scattered dark spots of brown, brown color located closer to the border
annual layer. These formations are called core repeats. Core repeats are formed due to damage to the cambium by insects or frost and resemble the color of the core.
Vessels
On the cross-section (end) of hardwood, holes are visible, representing cross-sections of vessels - tubes, channels of various sizes, intended for conducting water. According to their size, vessels are divided into large, clearly visible to the naked eye, and small, invisible to the naked eye.
Large vessels are most often located in the early wood of annual layers and in cross section form a continuous ring of vessels. Such hardwoods are called ring-vascular. In ring-vascular species in late wood, small vessels are collected in groups, clearly visible due to their light color. If small and large vessels are evenly distributed across the entire width of the annual layer, then such species are called scattered vascular hardwoods.
In ring-vascular hardwoods, the annual layers are clearly visible due to the sharp difference between early and late wood. In deciduous vascular species, such a difference between early and late wood is not observed and therefore the annual layers are poorly visible.
In deciduous ring-vascular species, small vessels in late wood form the following types of groupings: radial - in the form of light radial stripes resembling flames (Fig. 6, a - oak, chestnut); tangential - small vessels form light solid or intermittent wavy lines extended along the annual layers (Fig. 6, b - elm, elm, elm); scattered - small vessels in late wood are located in the form of light dots or dashes (Fig. 6, c - ash).
In Fig. Figure 6, d shows the location of vessels in a deciduous scattered vascular species (walnut). The vessels are distributed evenly across the entire width of the annual layer.
In radial and tangential sections, the vessels have the appearance of longitudinal grooves. The volume of blood vessels, depending on the breed, ranges from 7 to 43%.
Resin passages
A characteristic feature of the structure of coniferous wood is resin ducts. There are vertical and horizontal resin passages. Horizontal ones pass along the core rays. Vertical resin ducts are thin narrow channels filled with resin. On a cross section
Rice. 6. Types of vessel groupings:
a, 6, c - ring-vascular rocks with radial, tangential and scattered groupings, d - dispersed-vascular rock
vertical resin ducts are visible in the form of light dots located in the late wood of the annual layer; On longitudinal sections, resin passages are visible in the form of dark strokes directed along the axis of the trunk. The number and size of resin ducts depend on the type of wood. In pine wood the resin ducts are large and numerous, in larch wood they are small and few in number.
Resin ducts occupy a small volume of trunk wood (0.2-0.7%) and therefore do not have a significant effect on the properties of the wood. They are important when tapping, when resin (resin) is obtained from growing trees.
§ 3. Microscopic structure of wood
Examination of wood under a microscope shows that it consists of tiny particles - cells, mostly (up to 98%) dead. A plant cell has a thin transparent membrane, inside which there is a protoplast, consisting of cytoplasm and nucleus.
The cell membrane of young plant cells is a transparent, elastic and very thin (up to 0.001 mm) film. It consists of organic matter - fiber, or cellulose.
As it develops, depending on the functions that a particular cell is designed to perform, the size, composition and structure of its shell change significantly. The most common type of change in cell membranes is their lignification and suberization.
Lignification of the cell membrane occurs during the life of cells as a result of the formation of a special organic substance in them - lignin. Lignified cells either stop growing altogether or increase in size to a much lesser extent than cells with cellulose membranes.
Cellulose in the cell wall is presented in the form of fibers called microfibrils. The spaces between microfibrils are filled mainly with lignin, hemicelluloses and bound moisture.
During growth, the cell membranes thicken, leaving unthickened areas called pores. The pores serve to conduct water and dissolved nutrients from one cell to another.
Types of wood cells. The cells that make up wood vary in shape and size. There are two main types of cells: cells with a fiber length of 0.5-3 mm, a diameter of 0.01-0.05 mm, with pointed ends - prosenchymal and cells of smaller sizes, having the appearance of a multifaceted prism with approximately the same side sizes (0. 01-0.1 mm), - parenchymal.
Parenchyma cells serve to deposit reserve nutrients. Organic nutrients in the form of starch, fats and other substances are accumulated and stored in these cells until spring, and in the spring they are sent to the crown of the tree to produce leaves. Rows of parenchyma cells are located radially around the tree and are part of the medullary rays. Their number in the total volume of wood is insignificant: for coniferous species 1-2%, for deciduous species - 2-15%
The bulk of wood of all species consists of prosenchymal cells, which, depending on the vital functions they perform, are divided into conductive and supporting or mechanical. Conducting cells in a growing tree serve to conduct water with solutions of mineral substances from the soil into the crown; supporting ones create the mechanical strength of the wood.
Wood fabrics. Cells of the same structure, performing the same functions, form wood tissue.
In accordance with the purpose and type of cells that make up the tissues, they are distinguished: storage, conductive, mechanical (supporting) and integumentary tissues.
Storage tissues (Fig. 7, a, b) consist of short storage cells and serve to accumulate and store nutrients. Storage tissues are found in the trunk and roots.
Conducting tissues consist of elongated thin-walled cells (Fig. 7, c) (vessels, tubes), through which moisture absorbed by the roots passes to the leaves.
The length of the vessels is on average about 100 mm; in some species, for example oak, the vessels reach 2-3 m in length. The diameter of the vessels ranges from hundredths of a millimeter (in small-vascular breeds) to 0.5 mm (in large-vascular breeds).
Mechanical tissues (supporting) are located in the trunk (Fig. 7, d). These fabrics provide stability to the growing tree. The more of this tissue, the denser, harder, and stronger the wood. Mechanical tissues are called libriform.
Integumentary tissues are located in the cortex and play a protective role.
The structure of coniferous wood. Coniferous wood is distinguished by its comparative simplicity and regularity of structure. Its bulk (90-95%) consists of elongated cells arranged in radial rows with obliquely cut ends, called tracheids. The walls of tracheids have pores through which they communicate with neighboring cells. Within the annual layer, early and late tracheids are distinguished. Early tracheids (Fig. 7, e) are formed in spring and early summer, have thin shells with pores, wide cavities and serve to conduct water with dissolved minerals. In early tracheids, the size in the radial direction is larger than in the tangential direction. The ends of early tracheids are rounded.
Late tracheids are formed at the end of summer, have narrow cavities and thick cell membranes, and therefore perform a mechanical function, giving strength to the wood. The size in the radial direction is smaller than in the tangential direction.
The number of pores on the walls of early tracheids is approximately 3 times greater than on the walls of late tracheids. Tracheids are dead cells. In the trunk of a growing tree, only the newly formed annual layer contains living tracheids.
Resin ducts are a structural feature of coniferous wood.
They are cells that produce and store resin. Some species have only resin cells separated from each other (fir, yew, juniper); in other species, resin cells are connected into a system and form resin passages (pine, spruce, larch, cedar). There are horizontal and vertical resin passages, which together form a single system of communicating channels.
Horizontal resin passages run along the core rays and are clearly visible on a tangential section of the trunk.
The microscopic structure of coniferous wood is shown in Fig. f. 8, a.
Wood parenchyma in conifers is not widespread and consists of single parenchyma cells elongated along the length of the trunk or cells connected in long rows running along the axis of the trunk. Yew and pine do not have wood parenchyma.
Structure of deciduous wood. Compared to conifers, deciduous trees have a more complex structure (Fig. 8, b). Basic
The volume of hardwood wood consists of vessels and vascular tracheids, libriform fibers, and parenchyma cells.
Vessels are a system of cells that serve in a growing tree to conduct water with minerals dissolved in it from the roots to the leaves. Water from the vessels passes to neighboring living cells through the pores present in the side walls of the vessels.
Libriform fibers (see reef 8, b) are the most common cells of deciduous wood and make up their bulk (up to 76%). The remaining volume of wood consists of wood parenchyma cells. These cells can be collected in vertical rows called cords of woody parenchyma. Libriform fibers are long cells with pointed ends, thick membranes and narrow cavities. The walls of libriform fibers are always lignified and have narrow channels - slit-like pores. The length of the libriform fibers is in the range of 0.3-2 mm, and the thickness is 0.02-0.005 mm.
Libriform fibers are the strongest elements of hardwood wood and perform mechanical functions.
The sizes and quantitative ratio of the various cells that make up wood, even in the same species, can vary depending on the age and growth conditions of the tree.
Parenchyma cells that perform storage functions in deciduous wood primarily form medullary rays.
The medullary rays of deciduous trees are more developed than those of conifers. The width of the medullary rays can be narrow, single-row, consisting of one or four rows of cells elongated along the radius, or wide, multi-row, consisting of several rows of cells in width. In height, the medullary rays consist of several dozen rows of cells (up to 100 or more in oak and beech). On a tangential section, single-row rays are presented as a vertical chain of cells; multi-row rays are lentil-shaped.
Deciduous trees shed their leaves in the winter and need large amounts of reserve nutrients to produce new leaves in the following spring, so hardwood wood contains more woody parenchyma cells.
The influence of the structure of wood on its physical and mechanical properties. The fine structure of the cell membrane has a significant impact on the properties of wood. A decrease in the amount of bound moisture leads to a decrease in the distances between microfibrils, which increases the adhesion between them and the content of solid wood pulp per unit volume. All this leads to an improvement in the mechanical properties of wood. On the contrary, with an increase in the amount of bound moisture, the microfibrils move apart, which reduces the mechanical properties of wood.
Microfibrils are located predominantly along the long axis of the cell. This determines the greater mechanical strength of wood along the grain.
The dimensions of individual anatomical elements also affect the physical and mechanical properties of wood. Since late tracheids have greater wall thickness, increasing the late zone content in the annual layers leads to increased density, hardness and mechanical strength. Similarly, in hardwoods, increasing libriform fiber content, especially those with thick walls, results in increased mechanical properties.
Features of the microscopic structure of deciduous and coniferous wood determine the difference in their properties. The grain of softwood wood is straight. Therefore, coniferous species have higher strength values at the same density. Hardwood has some
tortuosity of the fibers, as a result of which it has higher impact strength and higher strength when clumping along the fibers. The wood of deciduous ring-vascular species bends better, since the early wood contains vessels that allow the wood to compact without destruction.
2. Physical properties of wood
The physical properties of wood are those that are determined without violating the integrity of the test sample or changing its chemical composition, i.e., they are revealed by inspection, weighing, measuring, drying.
The physical properties of wood include: appearance and smell, density, humidity and associated changes - shrinkage, swelling, cracking and warping. The physical properties of wood also include its electrical, sound and thermal conductivity, and macrostructure indicators.

§ 4. Properties that determine the appearance of wood
The appearance of wood is determined by its color, shine, texture and macrostructure.
Color. The color of wood is given by the tannins, resins and dyes contained in it, which are located in the cavities of the cells.
Wood from species growing in different climatic conditions has different colors: from white (aspen, spruce, linden) to black (ebony). Wood from species growing in hot and southern regions has a brighter color compared to wood from temperate zone species. Within the climatic zone, each tree species has its own special color, which can serve as an additional feature for its recognition. Thus, hornbeam wood is light gray in color, oak and ash wood is brown, and walnut wood is brown. Under the influence of light and air, wood of many species loses its brightness, acquiring a grayish color in the open air.
Alder wood, which has a light pink color when freshly cut, soon after felling darkens and acquires a yellowish-red color. Oak wood that has lain in water for a long time acquires a dark brown and even black color (stained oak). The color of the wood also changes as a result of it being damaged by various types of fungi. The color of wood is also influenced by the age of the tree. Young trees usually have lighter wood than older trees. The wood of oak, pear and white acacia, boxwood, and chestnut has a stable color.
The color of wood is important in the production of furniture, musical instruments, carpentry and art products. The color, rich in rich shades, gives wood products a beautiful appearance. The color of some wood species is improved by subjecting it to various treatments - steaming (beech), staining (oak, chestnut) or staining with various chemicals. The color of wood and its shades are usually characterized by definitions - red, white, pink, light pink, and only if specially necessary, according to an atlas or color scale.
Gloss is the ability to directionally reflect light. The shine of wood depends on its density, number, size and location of the core rays. Core rays have the ability to directionally reflect light rays and create shine on a radial section.
The wood of beech, maple, elm, sycamore, white acacia, and oak is particularly shiny. The wood of aspen, linden, and poplar, which has very narrow core rays and relatively thin walls of mechanical tissue cells, has a matte surface.
The shine gives the wood a beautiful appearance and can be enhanced by polishing, varnishing, waxing or covering with transparent films of artificial resins.
Texture is a pattern that is obtained on sections of wood when cutting its fibers, annual layers and medullary rays. The texture depends on the anatomical structure of individual wood species and the direction of the cut. It is determined by the width of the annual layers, the difference in the color of early and late wood, the presence of medullary rays, large vessels, irregular arrangement of fibers (wavy or tangled). Coniferous species in a tangential section, due to the sharp difference in the color of early and late wood, give a beautiful texture. Deciduous species with pronounced annual layers and developed medullary rays (oak, beech, maple, elm, elm, sycamore) have a very beautiful texture in radial and tangential sections (Fig. 9 inset). Wood with an irregular arrangement of fibers (the grain is wavy and tangled) has a particularly beautiful pattern.
Softwood and softwood have simpler and less varied patterns than hardwood.
Using clear varnishes can enhance and bring out the texture.
Special methods of wood processing are often used - peeling plywood ridges at an angle to the direction of the fibers, radial planing, pressing or replacing with an artificial texture - the surface is painted with an airbrush to match the texture of valuable species or pasted over with textured paper.
The texture determines the decorative value of wood, which is especially important in the manufacture of artistic furniture, various crafts, when decorating musical instruments, etc.
The smell of wood depends on the resins, essential oils, tannins and other substances contained in it. Conifers - pine and spruce - have a characteristic smell of turpentine. Oak smells of tannins, while backout and rosewood smell of vanilla. Juniper smells pleasant, so its branches are used to steam barrels. The smell of wood is of great importance when making containers. When freshly cut, wood has a stronger odor than after drying. The kernel smells stronger than the sapwood. Individual species can be identified by the smell of wood.
Macrostructure. To characterize wood, it is sometimes sufficient to determine the following macrostructure indicators.
The width of the annual layers is determined by the number of layers per 1 cm of a segment measured in the radial direction on the end section.
The width of the annual layers affects the properties of wood. For coniferous wood, an improvement in properties is noted if there are at least 3 and no more than 25 layers in 1 cm. In deciduous ring-vascular species (oak, ash), the increase in the width of the annual layers occurs due to the late zone and therefore the strength, density and hardness increase. For the wood of deciduous scattered vascular forests (birch, beech), there is no such clear dependence of properties on the width of the annual layers.
The content of late wood (in%) is determined on samples from coniferous and ring-vascular deciduous wood. How
The higher the latewood content, the greater its density, and therefore the higher its mechanical properties.
The degree of equilayering is determined by the difference in the number of annual layers in two adjacent sections 1 cm long. This indicator is used to characterize the resonant ability of spruce and fir wood.
When processing wood with cutting tools, hollow anatomical elements (vessels) are cut and irregularities are formed on the surface of the wood. In species such as oak, ash, and walnut, the amount of structural irregularities is significant. Since the wood of these species is used for finishing products, before polishing it is necessary to reduce the size of these irregularities. For this purpose, a special operation is performed, which is called pore filling.

§ 5. Wood moisture content and properties associated with its change
Humidity. Wood moisture content is the ratio of the mass of moisture contained in a given volume of wood to the mass of absolutely dry wood, expressed in %. Humidity is determined according to GOST 16588-79.
Absolutely dry wood in small samples can be obtained by drying it in special cabinets.
Moisture in wood permeates cell membranes and fills cell cavities and intercellular spaces. Moisture that permeates cell membranes is called bound or hygroscopic. Moisture that fills cell cavities and intercellular spaces is called free, or capillary.
When wood dries, first free moisture evaporates from it, and then hygroscopic moisture. When moistening wood, moisture from the air permeates only the cell membranes until they are completely saturated. Further moistening of wood with filling of cell cavities and intercellular spaces occurs only with direct contact of wood with water (soaking, steaming, fusion).
The total amount of moisture in wood consists of free and bound moisture. The maximum amount of free moisture depends on how large the volume of voids in the wood is that can be filled with water.
The condition of wood in which the cell membranes contain the maximum amount of bound moisture, and the cell cavities contain only air, is called the hygroscopic limit. The humidity corresponding to the hygroscopic limit at room temperature (20°C) is 30% and practically does not depend on the breed.
The following stages of wood moisture are distinguished: wet - kept in water for a long time, humidity above 100%, freshly cut - humidity 50-10C%; air-dry - stored in air for a long time, humidity 15-20% (depending on climatic conditions and time of year); room-dry - humidity 8-12% and absolutely dry - humidity 0%. The moisture content in the trunk of a growing tree varies along the height and radius of the trunk, and also depending on the time of year. The moisture content of pine sapwood is three times higher than the moisture content of the core. In deciduous trees, the change in humidity along the diameter is more uniform.
Along the height of the trunk, the moisture content of the sapwood in conifers increases up the trunk, but the moisture content of the core does not change. In deciduous trees, the moisture content of the sapwood does not change, but the moisture content of the core decreases up the trunk.
Young trees have higher humidity and its fluctuations throughout the year are greater than older trees. The greatest amount of moisture is contained in the winter (November-February), the minimum - in the summer months (July-August). The moisture content in the trunks changes throughout the day: in the morning and evening the humidity of the trees is higher than during the day.
To determine the moisture content of wood, the drying method and the electrical method are used.
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