Ok, so I've seen lately some requests for help identifying wood and the
request to measure density comes up. So I imagine one is supposed to
measure accurately the volume of the wood and the weight to find density.
1) Doesn't the moisture content of the wood have to be taken into account?
Won't a sample with a mc of 20% be heavier than a sample with a mc of 10%.
I havn't seen reference to measuring the mc of the wood.
2) What is the standard unit of measure? lb/cubic in?
Yes. Most tables of wood density include the moisture content used in the
measure. If you can measure your wood's mc, then adjust accordingly. If
not, you can at least give yourself some error bound.
Specific gravity seems to be common. Calculate the density of the wood
and divide by the density of water.
I think that the density measure is not an extremely valuable measure, but
it can make the difference if you know little about the wood in question.
For example, I found some luaun that the dealer said was quite light but
didn't know the exact species. I measured and weighed it and found (on the
web) that there was only one really light species and it was a similar colour
to one heavier species. How to tell them apart? The density told me it was
the heavier one and the dealer was less than, ummm..., correct.
The engineer in me says I'd rather have more info than less.
Wood moisture content is usually measured as percentage of dry weight. It
is therefore possible, with green wood, to have the reported moisture
content exceed 100%. For this reason, green wood moisture content is
usually expressed as percent of present weight.
+ + +
It is terribly complicated, at least in the US.
you can measure the volume of the wood (green)
you can measure the volume of the wood (ovendry)
you can measure the weight of the wood (ovendry)
and start calculating.
Perhaps with enough imagination you can actually use the resulting figure
Over here we take wood at 12% or 15% and weigh it.
This is expressed per cubic meter or cm.
Then we know what we have. No imagination required.
Really? Makes it hard as hell to get that 6 to 8% you need for furniture and
cabinet work, doesn't it?
"Ain't no man can avoid being born average, but there ain't no man got to be
common." Satchel Paige
+ + +
Well, we are in the Netherlands (with Holland being some tens of kilometers
away, and today central heating is pretty common (personally I don't have
it, but I am an exception).
The OP didn't specify what purpose the wood is to be put to. If I take a
standard table of wood densities this gives the data mostly at somewhere
between 12-15%, as this will be what is used for more purposes. The actually
desired humidity of wood can be a little higher or lower depending on where
the final product is to be put, but 6-8% is not on the books. Some
woodtraders do have problems with kilns in Germany which do dry to 8% and
"forget" to take out "our" wood at 12%. Some do sue.
A fair amount of imported wood is dried here to its final moisture content.
The real problems occur in construction when the builders put supplied
wooden doors, doorframes, etc outside in the rain for a few weeks before
putting them in.
HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.