Machine WoodWorking 2, WASSCE (SC), 2020

Question 3

 

Question 3a

required candidates to list two defects each from the classes of timber defects

 

Question 3b

required candidates to state two qualities of waterborne preservatives.

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Question 3c

required candidates to list two methods of seasoning timber.

 

Observation

 

The expected responses are:

    (3A)        Types of  Natural defect:

  • Growth defects
    • brittle heart
    • heart rot
    • burr
    • gum veins and pocket
    • resin canals and pockets
    • insect holes
    • knots
    • shakes

            -      Grain defects       

    • cross grain
    • diagonal grain
    • interlock grain
    • spiral grain
    • wane or weney edge

     

    (3B)

    Types of seasoning defects:

          • case hardening
          • sap stain
          • end split
          • warp (cup, twist, bow or camber, spring)
          • check (end, heart, internal, ray, through, surface)
          • collapse

           

     (3C)

Methods of seasoning timber:

      • air / natural seasoning
      • kiln / accelerated /artificial/ seasoning
      • chemical seasoning
      • water seasoning.

 

   
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