Everything about wood

physical characterisitcs:

1. Specific gravity: The weight / volume ratio depends on the moisture content of the wood, but it is generally in direct contact with the bulky wood, so that you can use hard wood whenever you want.

Wood color: The durability of wood is directly related to their darkness. Also inside the wood is darker from outside and the layers formed in the spring are brighter than summer wood. The color of several important wood are:

Tabriz (White), Poplar (Cream), Shamshad (Lime Yellow), Eucalyptus (Reddish-brown), Walnut (Dark Gray Gray), Ebony (Black).

3. Resistance and electrical and thermal conductivity of wood: We must know that wood is a suitable thermal and electrical insulation, and in many applications it is related to the property of wood, such as: kebab, kettle and building construction They do. The other property is the acoustic property, the gypsum also has the property after the wood, and the same fabric and satin, velvet curtains and egg shoulder are also absorbent.

Mechanical properties of wood:

Wood Hardness: The resistance of wood to the penetration of a body. The stiffness and stiffness of the two are distinct. (Hardness, resistance to breakage and failure), it is important to know that the hardness of the wood with its specific gravity is directly related to the increase in moisture, and the hardness of the wood is very important, as well as the moisture content.

2. Flexural strength: the use of wood in the construction of roofs of houses, electric blades, bridges and … and the last mechanical parameter is tolerance to tension and pressure.

Effect of moisture in wood:

We have three types of moisture:

1. Fundamental water: which is in the molecular structure of wood.

2- Fresh water: 0% to 30%, the most important moisture in the wood.

3. Free water: 30% to a maximum of 200%, ie any dry wood is absorbed by water to 2 times its own weight. Therefore, wood is a porous and sponge material with its environment in the exchange of moisture. (If it has a higher moisture content, and if it is absorbed by the moist medium, it absorbs moisture)

One of the most important problems in the wood industry is preventing this moisture exchange. Because it causes deformation and tilt of wooden products. If the wood loses its water, it’s called stretch and if it absorbs moisture, it will be introduced to swirling, from 30%.

Benefits of Wood:

1. Thermal insulation and refrigeration.

2. Relative mechanical strength and elasticity of the impact.

3- Ability to pay for surface, color, carving and cutting.

4- Ability to correct the properties (anti-fire, anti-moisture and antifungal).

5- Cheap, affordable and easy to build.

6. Renewability of the tree after cutting.

7. Non-pollution of the environment or return to the environment (nature).

8. Acoustic property.

Disadvantages of wood drying:

Loosening and loosening the nodes.

2- Change the dimensions.

3- Folding and tilting timber.

Inner wood defects:

1. Heavier than synthetic material

2. Attack of living organisms (fungi, rodents, insects)

3. Flammability

4. Failure to reuse the original form

5. Failure and failure

6. Non-homogeneity

7- Connection weakness

Wood protection methods:

traditional way:

1- Half-burning: neutralizes the attacking agents and moisture.

2- Lubrication of vegetable and animal oils: The outer wall of wood lubricates oil that prevents moisture but does not affect the fire and living factors as it is washed off one day. (Not permanent) immersed in petroleum products.

3- Keep the wood dry.

New wood preservation methods are based on two factors:

1- Use of chemicals that protect wood against all threats and inject wood instead of wood.

What materials are used to keep wood?

1- Kerosene: One of the most important wood preservatives for coal distillation. It combines toxic and wood against living organisms and is a stable and non-washable material that does not come out of the wood. Both in pure form and in combination with bitumen or oil.

2- Pentachlorophenol: The other oil-based shields are used instead of kerosene and oil.

3. Metal salts: They are water-soluble proteins, such as: Carmitated copper arsenate or Keratinized chlorine.

Polymeric materials, such as PEGs, take on wood and prevent the exchange of wood mechanism and living factors. Contrary to what is injected into the depth of the wood, it is an anti-fire agent that prevents the flame from spreading.

In addition to the above methods, there are other methods that are used for two purposes and to some extent protect the wood, such as: painting the wood and applying varnish and alcohol or using a polymer.

Wood cutting types:

1. Radial cut

2. Tangential cut

Plumbing: to put small pieces of wood together and connect them in order to reach larger levels. The basic point is how to put the wood together so that its negative reactions are minimized; and the main thing in this way is to use the same wood along the way. (Needle – needle, broad leaf – broad leaf, young – young, old – old, inside wood – inside wood, radial – radial)

Fittings in wood:

As stated above, despite the plastic, glass and metals, wood can not be shaped and pieces made in one piece. So you first split the wood into small pieces and connect them together to make them. The connection is carried out in three ways, although three methods are done simultaneously.

A) Use of wooden fittings: that is, creating special geometric shapes in the wooden parts that we want to connect. These geometric shapes, while building up enough to increase the contact surface, such as: Clasp, tabs, fasteners, straws