Transcript Wood

Wood
MSE 220
Spring, 2009
Strength of wood increases as it dries. A board in
the green condition weighs 11.2 lbs, and in the
dry condition weighs 9.8 lbs.
Find: (a) the moisture content
(b) the shrinkage in %
Solution
Moisture content = weight of water in wood/dry
weight
= (11.2 lb. – 9.8 lb.)/9.8 lb.
= 14.3%
Shrinkage: Volume shrinkage = 1.6% per 4%
decrease in moisture
Therefore, Volume Shrinkage = 1.6%/4% * 14.3%
= 5.7%
Decay & Destruction
• Four factors that lead to degradation:
– Fungi
– Bacteria
– Insects
– Marine organisms
• Four ways to prevent degradation:
– Reduce moisture
– Chemical treatment
– Use heartwood from decay resistant species
– Painting or prohibiting insect entry