Wood MC/Math problem.
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jebatty said:
OK, so that means that wood MC is a relative quantity rather than an absolute quantity, and wood with an absolute moisture content by weight of 50% has a defined MC of 100%. Interesting, I didn't know that. Rick
I know the wood we done yesterday was very wet when loading unloading you could tell it had dryed up quite a bit,but no help on the MC
The debate never ends over what is moisture content, It doesn't really matter how you define it as long as everyone uses the same definition. I've seen at least three definitions tossed around here over and over.
If you want to use the definition used by the U.S. Forest Products Laboratory and most professional organizations I know and lumber kiln operators and legal definitions stamped on lumber it makes the conversation a lot simpler. And that is the definition that Jim (jebatty) gave. According to Hoadley's fine book on wood technology, "Understanding Wood", moisture content is defined as "the weight of water in the cell walls and cavities of wood expressed as a percentage of oven-dry weight". So if a stick of wood after baking at 215 to 220F until it doesn't lose weight anymore weighs 10 pounds it has a moisture content of 0%. When it weighed 15 pounds it had a moisture content of 50%. And if it were a piece of western red cedar sapwood it could have weighed as much as 24 pounds when it was cut down. Yeah, 240% moisture content!
Just for fun, next time you knock down a hemlock take a chunk of it and put it in a vise and squeeze it real hard and ask yourself if it might be near half water by weight. That's 100% by the definition I'm referring to.
If you want to use the definition used by the U.S. Forest Products Laboratory and most professional organizations I know and lumber kiln operators and legal definitions stamped on lumber it makes the conversation a lot simpler. And that is the definition that Jim (jebatty) gave. According to Hoadley's fine book on wood technology, "Understanding Wood", moisture content is defined as "the weight of water in the cell walls and cavities of wood expressed as a percentage of oven-dry weight". So if a stick of wood after baking at 215 to 220F until it doesn't lose weight anymore weighs 10 pounds it has a moisture content of 0%. When it weighed 15 pounds it had a moisture content of 50%. And if it were a piece of western red cedar sapwood it could have weighed as much as 24 pounds when it was cut down. Yeah, 240% moisture content!
Just for fun, next time you knock down a hemlock take a chunk of it and put it in a vise and squeeze it real hard and ask yourself if it might be near half water by weight. That's 100% by the definition I'm referring to.
I think this is the ultimate practical answer to the firewood moisture content dilemma.
If we all had our wood split and stacked (and I think capped over top, but let's not start another endless debate in this thread) for 2 years or more there would be no use for moisture meters.
Okay, I have to weigh in (pun intended)...
aren't we all assuming that the weight of the wood is equal to the weight of the moisture? it may be 50% MC, but couldn't the actual weight distribution actually be something like 60/40 wood/water?
aren't we all assuming that the weight of the wood is equal to the weight of the moisture? it may be 50% MC, but couldn't the actual weight distribution actually be something like 60/40 wood/water?
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