T1 Air seasoning: explain the process (5 marks) · Industrial Technology Timber

T1 · Air seasoning: explain the process (5 marks)

Fits: 2023 Q15 (5). Also 2015 MC6, 2021 Q12, 2022 Q12. · 247 words · 6 chunks

T1.1 · PurposeSeasoning is the controlled removal of moisture from green timber until it is close to the equilibrium moisture content (EMC) of the place where it will be used. This reduces later shrinkage, warping and checking, and makes the timber lighter, stronger and easier to machine, glue and finish.T1.2 · SiteAfter conversion, the boards are stacked outdoors on a level, well-drained site, raised off the ground on bearers. This lets air circulate underneath and keeps the stack away from ground moisture and termites.T1.3 · StickersEach layer of boards is separated by stickers, which are thin battens of equal thickness placed at regular intervals and lined up vertically one above the other. Stickers let air flow over every face of every board and keep the stack flat so boards do not bow or twist.T1.4 · CoverA roof or cover protects the stack from rain and direct sun, and weights on top hold the upper layers flat. The board ends are sealed with wax or paint to slow end drying, which prevents end splits and checks.T1.5 · TimeThe stack is left for many months, or years for thick hardwood, while moisture slowly evaporates. Air drying can only bring timber down to the EMC of the outside air, so furniture timber is often finished in a kiln.T1.6 · JudgementAir seasoning is cheap because it uses little energy, and slow drying causes less internal stress. However, it is slow, needs a lot of yard space and gives less control over the final moisture content than kiln seasoning.

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