I'm not following that math at all?? Water is more dense (heavier) than wood. So I would think the moister % lost in the wood will not only match it's % in weight, but actually be higher than it's % of the weight, no?
The concept and math gets kind of wonky because % moisture content is expressed as the amount of water within a piece of wet wood compared to the weight of the same piece of wood when it is bone dry, whereas pct weight loss is just that. It amounts to your needing to account for the weight of the wood when comparing the absolute weight loss vs. change in moisture content. And now that that makes close to no sense let me try to give examples to explain it. Take a hypothetical piece of wood that weighs 10 pounds, bone dry. At 20% moisture content it will weigh 12 pounds. 10 pounds of wood and 2 pounds of water. 2/10=.2 or 20%. At 40% moisture content it will weigh 14 pounds. Still 10 pounds of wood, and now 4 pounds of water. 4/10=.4 or 40%. If its moisture content was 100% it would weigh 20 pounds. 10 pounds of wood and 10 pounds of water. So to get from 100% to 0%moisture content you would need to lose 50% of its weight (all water). Wood is 10 pounds. Water is 10 pounds. Wood+water starts at 20 pounds. So your loss by weight is 10/20=.5 or 50%. Where the moisture dropped from 100% to zero. To get from 100% to 20% moisture content (a loss of 80 points) you would need to lose 8 pounds. 20-12=8 pounds lost. Loss by pct of weight 8/20=.4 or 40% by weight but a drop of 80% by content. Let's say that your 16.2 pound split just happens to be the hypothetical piece of wood that is bone dry at 10 pounds. That would mean that was at 62% when you weighed it. 10 pounds of wood and 6.2 pounds of water. And when the piece reaches 20% you would see a loss of 16.2-12=4.2 pounds. The loss by percentage of weight would be. 4.2/16.2=.259 or 25.9% but there would be a drop of 42% points in moisture content. Not very many pieces of wood will weigh exactly 10 pounds when bone dry. So it get a little more complicated. The trick for comparing weight loss to moisture content is to add 100 to the moisture content and then divide the weight by that number to figure out how much one percent (or unit of weight) is. The 100 accounts for the weight of the wood relative to the % moisture content. Once you know what one unit of weigh is you can figure out what the pieces moisture content is at any other weight or its weight at any other moisture content. Doing that is how I knew that your guess that the piece of wood was at 40% and could lose 30% of weight wasn't possible: 16.2 pounds of wood. You are guessing that it is at 40%. The magic number to divide it by is 140. That's 100 parts for the wood and 40 parts of water. 16.2/140=.1157. So each percentage point of moisture content is .1157 pounds. The wood is 100 times that number because you always have 100% of your wood. Which means bone dry that piece, if it was at 40% when initially weighed would weigh 11.57 pounds. You guessed it could lose 30% of its weight and weigh 11.3 pounds. But 11.3 pounds is less than it will weigh bone dry. A drop of 30% of the weight from a piece of wood at 40% moisture content isn't possible. A drop of 30% in weight to reach 20% moisture content is probably realistic though. Figuring where you started if that happens. End with 11.3 pounds of wood at 20%. 100 parts wood and 20 parts water or 120 parts (units of weight). 11.3/120=.0942. So each unit of weight is .o942 pounds. You started at 16.2 pounds wet. 16.2/.0942=171. 171 units of weight or 100 parts of wood and 71 parts or pct water. That means that if you lose 30% of the weight to arrive at 20% moisture content you had to start at 71% moisture content. Basic rule of thumb when looking at absolute weight loss vs. pct moisture content is that a loss of 33% by weight will get you from 50% moisture to bone dry or 80% moisture to 20%.
Mr Bunion, Thanks for the great explanation and taking the time to do it! Got it! I did not know that's what was being referred to as "moister %" in firewood. No wonder the moister meters don't work very well!
Did this little test. Best explanation on why standing dead oak dries faster was the water cells in standing dead oak broke down and opened up. Anyway, it's something to use as a comparison.
Yes sir, that's what I'm saying. This particular red oak was standing dead, bark less (or the bark could be removed by hand), no punk to speak of , when the hyd. splitter was splitting it, water would ooze/squirt out around the wedge, it was fully saturated, 100%. I have 40 acres of woodland and a lot of dead red oak, we've had a drought here for the last 15 years or so and the trees finally just give up. So that's all I've been cutting, I'm pretty convinced I know what I'm talking about. Here's the way it works on my farm, the tree dies, very slowly, then the limbs start falling off, then the top falls off, then the bark, ----but, it's still wet/water logged, all the way until it falls and rots on the forest floor. But once it is cut, it dries much, much faster than a live green red oak. I've stuck my neck out, now cut it off. All the best!
Weigh in #2 01/18/2015 Split #1 15.6 lbs. loss of 0.6 lbs Split #2 9.2 lbs. loss of 0.6 lbs That's 9.6oz lost on each split, almost an entire beer in 1 week from each!
I have to agree I've had the same experience. Dead tree was cut stacked in rounds not split. Saturated wet. Split up stacked and drying time was quite short a couple months if I rember right. It was red oak as well
Yes a dead tree will dry quicker then a green one but I dont think that is what he is saying. After rereading his post yes I agree a dead tree will dry quicker then a live one, usually this is because some of the moisture has been removed already.
Update, splits still uncovered on the top of the stack and covered in snow. Wiped off snow weighed in again: Weigh in #1 01/11/2015 Split #1 16.2 lbs. Split #2 9.8 lbs. Weigh in #2 01/18/2015 Split #1 15.6 lbs. loss of 0.6 lbs. Split #2 9.2 lbs. loss of 0.6 lbs. Weigh in #3 02/10/2015 Split #1 15.6 lbs. loss of 0.6 lbs. Split #2 9.4 lbs. loss of 0.4 lbs. (or gained 0.2 lbs. since last weigh in!)
Was that just snow since the last weigh in or did they get rain too? It was warmer in late January, meaning they should have lost some during that spell but there were some pretty heavy rains somewhere in there too as I recall. (We are about 90 miles apart so the weather must be somewhat similar.)
ok, time for an update! I can't believe it has been 6 months, WOW!! Time sure is flying by, scary. Enjoy each day guys, cause they are flying!! Weigh in #1 01/11/2015 Split #1 16.2 lbs. Split #2 9.8 lbs. Weigh in #2 01/18/2015 (after 1 week of seasoning) Split #1 15.6 lbs. loss of 0.6 lbs. Split #2 9.2 lbs. loss of 0.6 lbs. Weigh in #3 02/10/2015 (after 1 month of seasoning) Split #1 15.6 lbs. loss of 0.6 lbs. Split #2 9.4 lbs. loss of 0.4 lbs. (or gained 0.2 lbs. since last weigh in!) Weigh in #4 09/03/2015 (after 8 months of seasoning) Split #1 11.4 lbs. loss of 4.8 lbs. (WOW!!!!!!!! That's 1/3rd of it's weight!!!!!!!!!!!) Split #2 6.6 lbs. loss of 3.2 lbs. (WOW again!!) ok, so how much BEER has come out of the log so far? Split #1: 4.8lbs lost x 16oz per lb = 76.8 ounces, or about 1 SIX PACK of beer, and another half beer left over from the night before!!! That's pretty enlightening! These 2 splits will likely season another 2 years before I get to them, I wonder what they will weigh then? Any ideas?
I found some tables that suggest red oak weighs 68% of its green weight when seasoned to 20% moisture. Unless that wood was wetter than freshly cut your numbers wood suggest those pieces are 20ish percent moisture. The first one is around 70 and the second 67.
hmmmm....interesting! That's pretty amazing since the humidity today (and lately) was 90% (down to 81% now). AND, it was a very live green tree cut down the day before I bucked and split it. But these two splits are sitting on the top of a stack, in the sun about 3/4's of the day, uncovered.
