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.
Questions
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?
Frank
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.
Mike
No "eureka" here. Specific gravity is easy to compute by the submersion method.
George schreef
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. PvR
Over here, we take wood at 12% or 15% and put it back in the kiln until it's dry.
A Dog Named Stain schreef
PVR notes:
Really? Makes it hard as hell to get that 6 to 8% you need for furniture and cabinet work, doesn't it?
Charlie Self "Ain't no man can avoid being born average, but there ain't no man got to be common." Satchel Paige
Not if you're living in Holland. Something about that sea air. Also, IIRC, and it was some time back, central heating is not common.
George schreef
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. PvR
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