Wood and by products

Wood and by Products

1. Wood and by Products

2. Types of Wood Hard wood Hardwood is used for making cupboards, desks, wooden panels, door-frames and window fittings. It is extremely durable and resistant to rot, heat, pressure and can withstand changes in weather. Therefore, it can be used for the construction of floors, walls and ceilings as well. Types of hardwood commonly used in Pakistan are Mango tree ,Deodar, walnut tree wood and teak. Soft wood Softwood is lighter and more flexible than the hardwood but is more or less similar to it in strength. It is derived from evergreen trees and can be used for the construction of wooden floors, walls, desks, furniture, door and wooden panels. However, softwood might not be an ideal choice for walls and ceilings in urban houses. Softwood is mainly used in the making of doors, door panels, window frames and furniture. Some types of softwood can also be used as a flooring material. Commonly used softwoods in Pakistan are Pine ( chir pine), fir and Hemlock ( shekran ).

3. General properties of wood Generally materials expand in heat or summer while contract in winter. In case of wood this is not the case. The wood expands in winter acnd contracts in summer.

4. Seasoning Of Wood Seasoning is done to remove sap and water from the wood. KILEN SEASONING; Introducing steam to sealed container with wood in it by this sap is replaced by water steam followed by air Seasoning ELECTRIC SEASONING; Negative and positive charge are introduces on both side of the log and then electric current is passed. This dries the sap in the wood. CHEMICAL SEASONING; Wood is dipped into ammonium sulphate , the sap dissolves in it , afterwards wood is dried

5. DEFECTS IN WOOD KNOT ; Found mostly in soft woods. It is formed at the point of attatchment of branch SHAKE; It is the dead part of the tree as a result of a cut. STAR SHAKE; Throughout hollow CUP SHAKE ; When annual ring is effected due to a dead part in it RADIAL SHAKE ; In tree radial modular rays are present in which the sap moved. If any part of this radial sap is effected at any point it forms radial shake RIDGAL; As a result of cutting a branch a hollow depression forms called Ridgal . In it certain birds make nest TWIST; tree twists and rotates as it grows. Can be due to strong winds of climate change. This results in uneven sides of tree thus the wood strength decreases.

6. DECAY OF WOOD TERMITE ; f eeds on sap of the wood rest of the wood becomes like powder. When termite is exposed to air it dies. Due to this reason it moves in tunnels WOODBORER ; The insect maked through and through hole in the wood. Cure ; pesticides FUNGUS; Develops in damp areas resulting in surface of wood that in not breathable PARASITE; Feeds on tree such as wines.

7. BY PRODUCTS OF WOOD By product ; the leftover used to make something useful. Or Things made out of the leftover wood Due to scarcity of trees and wood and due to high cost of pure wood. The by-products of wood are used HARD BOARD PLYWOOD CHIPBOARD VENEER BOARD SOFT BOARD BLOCK BOARD MDF HDF VENEER BOARD

8. PLY BOARD Ply means layers It is made by layers of veneer ; thing sheet of wood Veneer is hard to break in the direction of its fibres but in opposite direction it is easily breakable So in case of ply wood the veneer sheets are put together in a way that each sheet has opposite direction of fibres attached parallel to each other . Usually the number of veneer used in ply is 3 and 5 Due to added strength the formation of ply makes it possible to provide wood for 2 to 3 homes from one log It give finish of solid wood On doors mostly grained ply is used In-between the veneer sheet a low quality wood veneer is used such as sumbal The thickness of ply available in market are 1/8” , ¼” and 0.5 inches Its strength is 4 to 5 times greater than hard board It can be painted polished and lacquered

9. FINE LINE PLY Its exterior layers are also of low quality veneer and in between the layers a thin layer of plastic is used. So it has artificial veneer,it can be used in panelling on walls and on ceilings. MARINE PLY It is water resistant. It is used to clad structural elements such as columns and walls. It is not commonly used . Its finish is beautiful. It is used for form work of R.C.C columns to create moulds for columns and structural elements. Horizontal members of common wood shuttering are made of Weeping Willow( kiker ), Indian Red Wood ( sheesham ) while vertical members of wood shuttering are made of eucalyptus.

10. HARD BOARD It is by-product of wood. Its one side is grained while other is smooth. Made through compression of particles without any glue. Its grained surface is result of draining water out of sheet through a net. Its fibres are porous therefore absorbs a lot of water. It also absorbs moisture from air especially in monsoon It can only be nailed and not grooved due to texture under it. It is easily breakable Use ;Base of drawers , Beds ,

11. SOFT BOARD Used for sound absorption It is not dense Its fibbers are loosely attached It cannot be painted It cannot be nailed and also it cannot be screwed directly Its panelling is done on walls Is also used as display board. It needs to be framed at edges Their dimensions change in response to changes in humidity. If these dimensional changes take place after the boards have been fixed they may cause bowing or gaps at joints. To avoid this the moisture content of board may first need to be adjusted to that of the surrounding air by conditioning. Conditioning is done by placing the boards in the room where they are to be fitted for 24 to 48 hours to attain the same moisture content.

12. MDF BOARD MDF is also regularly used in the making of furniture, cabinetry, wall panels, shelving, storage units, decorative molding, and doors. Due to its insular qualities in sound and heat, MDF, is also used in acoustic enclosures such as loudspeakers and sub-woofers. Sizes of standard board sheet are 4’-0”x8’-0” , 4’-0”x6’-0” and 4’-0”x12’-0”. The reason for these sizes that when the MDF board are placed in stores its ends become rough and need to be removed during making of a product such as doors. Even on its edges carving can be done. On its sides veneer is also used Its thickness ranges from 3mm to 25mm It is easy to paint A layer of emulsion is applied before painting it or sealer can be applied alternatively

13. HDF BOARD / HIGHT DENSITY FIBER BOARD It in more water repellent than MDF. In HDF and MDF glue is used in making of it and then it is compressed. The glue used is formaldehyde Even on its edges carving can be done. On its sides veneer is also used Its thickness ranges from 3mm to 25mm It is easy to paint A layer of emulsion is applied before painting it or sealer can be applied alternatively

14. CHIP BOARD / PARTICLE BOARD Wood is cut into small particles. every kind of waste wood can be used in making of chipboard. After cutting thin chips out of wood it is mixed with glue and in presence of steam its layering is done. Its layers are 3 quarter inch thick Sizes of standard chip board sheet are 4’-0”x8’-0” , 4’-0”x6’-0” and 4’-0”x12’-0”. The reason for these sizes that when the chip board are placed in stores its ends become rough and need to be removed during making of a product such as doors. It quickly absorbs water thus cannot be used in bathrooms and kitchen. It absorbs a lot of paint. When it absorbs water cavity is formed in it , in that’s insects can live in it. Sometimes its edges are laminated with layer of plastic to give it a smooth look. Otherwise its edges are very rough. It is then called “laminated board”,

15. Laminated boards are available in various colours and finishes in market. At one point Formica was used or pasted on both sides of chipboard before its use Formica pressed chipboard furniture is used in offices Formica finish generated finish of wood. Formica itself is a synthetic material. It is in form of a thin sheet. After this veneer boards were introduced in which external layers were of Teak ( Sagwan ) , commercial ply and Indian rose wood ( sheesham ) was used on either sides.Thus commonly called Vin board. In chipboards expansion and contraction is very low due to fine grains.