Got a quick question. The wood I split a few days ago was ranging between 22 to 28 percent. It’s from the fallen dead oak tree (for years) is now all almost showing around %20. To take the MC reading, do you always fresh split and take a new reading even the firewood is already a small split? Is it normal to lose 3-5 % in a few days?
You will definitely see a quick drop at the surface, as the air is working on that right away. Deeper in the wood will take quite a while.
Yes, that's how it needs to be done. Because.. Now, oak it's it's own special deal on that it's cells don't let out moisture like typical tree cells.
You want to know the MC of the center. Only practical way to get to the center is split it. Yes, I've seen daed standing red oak lose moisture content rather rapidly once the rounds have been split.
Always test on a freshly split piece of wood, in the center. You will want to keep in mind as well that the wood temperature should be at least 70f otherwise the reading will be off. Overnight in the house before splitting a piece should suffice.
I cut some standing dead oak, 9-10 months ago. Dragged them out of the snow. Tops were long gone. I took them because I feat I'd be short of seasoned wood this heating season. I wished I had put my mm on the wood when I first css'd it, but didn't . I split a few larger splits the other day and they were a point either side of 15%. I was happy.
Logs that had been dead and down for a long time reach an equilibrium moisture content based on the humidity, temperature, precipitation, wind and sun exposure... When this is considered “downed woody fuel”, as it is referred to by people who do fire danger ratings and fire behavior predictions, it loses moisture faster than wood that is drying for the first time. Wood over 3” in width/diameter is called 1000 hour fuel. So it takes 1000 hours of continuous conditions to get to its equilibrium moisture content. With all that said, if you are planning to burn the wood this winter, I think you are in pretty good shape if you can get the wood covered and have a month or two to let it dry out. If you can store it inside, you may lose moisture more quickly as the humidity is likely to be lower inside during the heating season... Agree with the advice to always test a fresh split to determine moisture content... you could also weigh a piece of wood and get an idea of how much moisture is lost by reweighing at one week intervals.. as the weight stops changing, you will know that you have reached its equilibrium moisture content... I’m very comfortable cutting dead red oak in September knowing it’ll be ready to burn during the coldest part of the winter. This only applies to the wood that I described above..
Used to do downed woody fuel inventories for the National Park Service. So it was not necessarily for firewood, but the concept is the same. Instead of getting to an equilibrium moisture content, we would strive to get to zero moisture using a drying oven. The concept is the same and just sped up with the oven.. We’d start by getting the “wet” weight of samples. Then pull the fuel out at particular time intervals and when there is no change in weight, the moisture content is theoretically zero. Take the starting weight, subtract the dry weight and you’d have the weight of the water... water content is expressed as a percentage of the dry weight... so for example, Initial weight of a piece of wood is 7 lbs. Once dried in the oven, the weight is 5 lbs. so the water weight is 2 lbs... 2 divided by 5 is 0.4 or 40% moisture content... it’s a little different when air drying as the equilibrium moisture content depends on the surroundings as air drying will never yield 0% moisture content except in Death Valley in July. Where I live, a piece of wood stored inside would seek an equilibrium moisture content of 7-10%. If you are testing a fresh split and getting 28%, you can grab a similar sized piece and assume it’s about the same... say the piece weighs (for simplicity) 12.8 lbs... after it sits for a while, it weighs 12.2 lbs. you can reasonably expect the moisture content is now 22%. After more time, it weighs 11.7 lbs.. now you expect it is about 17% moisture content... the math is naturally more complicated if the initial weight doesn’t magically align with the initial moisture meter reading. Also, since the moisture content isn’t uniform throughout the wood (higher or lower at the surface due to weather conditions at the time of testing) just using the % from the middle of the split could throw off the numbers. In the above example, theoretically if you were to throw the split in and oven, absent pyrolysis, you’d never get the piece to weigh less than 10 lbs, the point at which the moisture content has reached 0%... let me know if that doesn’t make sense..
The theory of it does make sense thanks. Anybody with real life experience with preferably with oak in the same situation.
You don't keep splitting the same piece, you take a new sample from the stack Preferably keep all your sample sizes and conditions the same. I used to take 3-5 splits, split them and test them and then in a month or two take another 3-5 splits from the same place in the stack and repeat. Look for a trend. Really the only accurate way to test is to keep weighing the same sample split(s). But a moisture meter should give a relative moisture content value and that's usually good enough.
As I mentioned, I’ve done it before... actually quite a bit. if it’s been dead for more than 6-7 years, it should be fine.... here’s one of them. It was burned within a couple months.. It was time....
I have cut some dead standing and brought it straight into the house. Sometimes a MM saves a little extra work. I found on several small standing dead trees. The moisture content was high near the ground but after 4 feet or so it was good to burn as is. Just something to keep in mind, even on downed trees. Some parts may be more wet than others. If your in need of wood keep them separated. Take the low and plan on using that. Set the wet aside for further stacking. For rapid drying two small wood racks near your stove are very helpful. One drys while you use the other alternatively. Not everyone can get permission for this tho I spent my first year with a cat stove and MM with stacks of wood around and behind my wood stove. It made a big difference on my small splits. Small drys faster than big
Great! So my plan to burn them with MC below %20 this Winter/March is doable! Thanks for the feedback and sorry for the confusion.
