Grade 10 woodwork – Preparation of Wood Quiz
1. What is the main purpose of seasoning timber before using it in furniture or buildings?
Seasoning removes excess moisture from timber so it reaches an equilibrium moisture content. This reduces shrinkage, warping and splitting when the wood is used indoors or in construction.
2. Which laboratory method gives the most accurate measurement of timber moisture content?
The oven-dry method is the standard laboratory technique: a sample is dried at a specified temperature until weight stabilises and moisture content is calculated accurately from the weight loss.
3. What is the most likely result when timber with high moisture content is fixed into indoor furniture without seasoning?
High-moisture timber will change dimension as it dries in service, causing warping, twisting and end checks; this ruins joints and the appearance of furniture.
4. Which drying method is fastest and allows control of temperature and humidity for seasoning timber?
Kiln drying uses controlled heat and humidity to reduce moisture quickly and uniformly, giving predictable results and reducing defects compared with slow air-drying.
5. What advantage does quarter sawn timber have over plain (flat) sawn timber?
Quarter sawn boards are cut radially from the log giving straighter grain, greater dimensional stability and less cupping or warping compared with plain sawn boards.
6. Which statement correctly describes heartwood compared with sapwood?
Heartwood is the inner, dead wood of the tree; it is often darker and contains extractives that make it more resistant to decay than the outer sapwood which is actively conducting water.
7. Why is end-grain sealing applied to freshly cut timber ends before drying?
End grain loses moisture much faster than face grain. Sealing the ends slows drying there, preventing rapid shrinkage that causes checks and splits.
8. Which defect is most commonly caused by incorrect stacking and poor support during seasoning?
Poor stacking and uneven support allow uneven drying and movement of boards, often causing cupping where one face shrinks differently from the other.
9. Which timber preservative is commonly used for long-term ground contact and is recognised in construction?
CCA is a common heavy-duty preservative used to protect timber in ground contact against decay and insects; it penetrates and fixes in the wood for long-term protection.
10. Which tool is best for marking a straight line parallel to the edge of a board when preparing timber?
A marking gauge sets a measured distance from the edge and scores a consistent line parallel to that edge, useful for joinery layout and accurate cutting.
11. What is the main purpose of a thickness planer (surface planer) in timber preparation?
A thickness planer removes thin layers from a board to produce uniform thickness and smooth faces, making boards ready for joinery and finishing.
12. Why must timber be acclimatised in the workshop before being cut and fixed into furniture?
Acclimatisation lets timber equalise its moisture with the workshop environment; this reduces the risk of later movement (shrinkage or swelling) after items are made.
13. Why are knots in timber a problem when preparing wood for fine furniture?
Knots are areas of irregular grain where branches were; they can split out, cause tools to chatter, weaken joints and may be considered unsightly in fine work.
14. Which sawing method uses parallel cuts tangent to the growth rings to produce wide boards quickly?
Plain or flat sawing slices the log with cuts parallel to the tangent of the growth rings, producing wide boards quickly and with less waste than quarter sawing.
15. What is the best typical moisture content for timber used indoors for furniture in Kenya's climate?
Indoor furniture is typically best made from timber around 10–14% moisture content; about 12% is a common target in many Kenyan workshops to match indoor equilibrium.
16. How should timber be stored on a site to reduce the risk of fungal decay?
Proper storage keeps wood dry and ventilated: bearers raise timber from the ground, a cover protects from rain but allows sides to breathe, reducing fungal growth.
17. What causes blue stain in stored timber?
Blue stain is caused by fungi that discolour sapwood; it does not usually reduce mechanical strength but harms appearance and market value.
18. Which adhesive is appropriate for exterior timber joints that must resist wet conditions?
Phenol-formaldehyde resins make strong, water-resistant bonds suitable for exterior structural joints; ordinary PVA and household glues are not sufficiently durable in wet conditions.
19. What does 'dressing' timber mean in the preparation process?
Dressing is the mechanical process of planing or surfacing rough-sawn timber to give even thickness, flat faces and a smooth surface ready for joinery and finishing.
20. Why do we chamfer or bevel sharp edges on timber parts before finishing?
Chamfering eases sharp edges, reducing the chance of splinters, improving durability of the edge and giving a cleaner appearance after finishing.
21. Which machine is best suited for making accurate cross-cuts on long boards in a woodworking workshop?
A table-mounted circular saw used with a mitre gauge or cross-cut fence makes accurate, repeatable cross-cuts on long boards and is standard in school workshops.
22. How can you avoid unsightly dark staining where metal meets damp timber during storage or construction?
Iron salts react with tannins in timber to cause dark stains; preventing contact, using coated/stainless fixings or a moisture barrier prevents this staining.
23. Why is sealing the end grain important before applying glue to a joint?
End grain acts like a sponge and quickly soaks up adhesive, reducing bond strength. Sealing or pre-coating controls absorption and allows a stronger glue line.
24. What are season checks in timber?
Season checks are small splits or cracks caused by uneven or rapid moisture loss, commonly appearing at board ends where drying is fastest; they are a drying defect.
25. What is the main purpose of seasoning wood before using it in carpentry?
Seasoning removes excess moisture so wood is stable, less likely to warp, crack or rot, and will hold joints and finishes better.
26. Which of the following is not a common method of seasoning wood?
Boiling is not used to season wood because it adds water; common methods are air drying, kiln drying, and solar-assisted drying.
27. What is a sticker in the context of timber seasoning?
Stickers are small straight strips placed between layers of stacked timber to allow even airflow and promote uniform drying.
28. Which action best prevents end checking (cracks at the ends) during drying?
Sealing the ends with paint or wax slows moisture loss at the ends and reduces the risk of checks forming from rapid drying.
29. What is a typical target moisture content for seasoned timber used indoors in Kenya?
About 10–14% is commonly used for indoor furniture and joinery; 12% is a typical target to match indoor equilibrium moisture.
30. Which tool is commonly used to measure the moisture content of wood?
A moisture meter gives a direct reading of wood moisture content, which is essential before using or finishing timber.
31. Which statement correctly distinguishes heartwood from sapwood?
Heartwood is older, non-living, often darker and usually more resistant to decay; sapwood is the active outer wood that transports water.
32. What is the main advantage of kiln drying over air drying?
Kilns use controlled temperature and humidity to dry timber faster and more uniformly than natural air drying.
33. How should timber be stacked during air drying for best results?
Stacking boards flat with aligned stickers ensures even support and airflow; end protection reduces checking.
34. Uneven or rapid drying commonly causes which defect in timber?
Uneven moisture loss causes internal stresses that lead to warping, cupping, twisting or bowing of boards.
35. What is a main advantage of quarter sawn timber over plain sawn timber?
Quarter sawing produces boards with vertical grain that shrink less across the width and are more stable for furniture.
36. Why is debarking logs done before converting them into timber?
Removing bark prevents insect attraction, reduces decay, and helps the log to season more evenly.
37. Which method gives the longest lasting protection when treating timber for ground contact posts?
Pressure-treated timber forces preservatives deep into the wood and provides long-term protection against decay and insects in ground contact.
38. When is the correct time to mark out (measure and mark) wood before cutting?
Marking after measuring and before cutting ensures accuracy and prevents mistakes during conversion.
39. What is the main purpose of using stickers of consistent thickness between boards when stacking?
Uniform sticker thickness keeps boards parallel and allows consistent air movement so all boards dry evenly.
40. Which description matches the defect called a 'cup' in a board?
Cup is a curvature across the face of the board causing a concave or convex face across its width.
41. How does tangential shrinkage compare to radial shrinkage when wood dries?
Wood shrinks more along the tangent to growth rings than across the radius, causing most of the movement and distortion.
42. Which preservative method involves forcing chemicals deep into wood under pressure?
Pressure impregnation uses pressure to push preservative liquids into the wood structure, protecting it internally and externally.
43. What is the primary purpose of planing timber during preparation?
Planing removes small amounts of wood to create a flat, smooth, and accurately thick surface ready for joining or finishing.
44. How can stored timber be protected from insect attack and moisture while awaiting use?
Raising timber and covering it while allowing airflow prevents ground moisture and reduces insect infestation and mould growth.
45. What does the term 'green wood' mean?
Green wood is recently felled timber which has not been dried and therefore holds much water and needs seasoning.
46. What is meant by the 'conversion' of logs in sawmilling?
Conversion is the process of sawing a round log into flat sections (boards, planks) suitable for use or further processing.
47. Which saw type is best suited for ripping a board along the grain?
A rip saw has teeth shaped to cut along the grain efficiently, whereas a crosscut saw is designed to cut across the grain.
48. Why do we season wood to its equilibrium moisture content (EMC)?
Seasoning to EMC ensures wood stays stable in service; if moisture differs from the environment it will swell or shrink causing problems.
49. What is a 'check' in timber preparation?
Checks are splits that develop from the ends inward when the ends dry and shrink faster than the rest of the board.