4.2 b Flashcards
natural timber
wood cut directly from the tree, cut into planks of diff sizes
difference between hardwood and softwood is in…
in how the fibre and pores work
where is tensile strenght greater in timber
along the grain (fibre) than across the grain (matrix)
damp resistance of timber
timber absorbs moisture from the air during humid periods and releases moisture during dry periods
hardwoods
wood from decidious trees (lose their leaves) that bear fruit. slow growing => considered non renewable
softwoods
wood from coniferous (keep their leaves) trees – cone bearing ones
softwoods features, in comparison to hardwoods
grow faster
have lower density
more likely to absorb water
less tensile strength
more lightweight
easier to work with
catch fire easier
wood grain patterns
flat grain
vertical grain
end grain
hygroscopic
absorbs moisture of surrounding environment
equilibrium moisture content
when the tree is in a stable environment, not gaining or losing moisture
define seasoning
drying of timber to reduce the moisture content of wood
seasoning methods
kiln seasoning
air drying
kiln seasoning adv
speeds up process
insects killed off
moisture content can be brought to a specific level
kiln seasoning disadv
expensive
skilled person needed
energy use
air drying adv
no need for expensive equipment
reduced labour costs
little energy use
