Hi All,
Something funny that I noticed today, but is probable not news to anyone with more experience.
Last week I pulled out a half-sheet of baltic birch plywood that I was going to work on, 1/2 inch thick. Then I got sidetracked and I left it on the concrete floor in the garage. I sealed the floor before I moved in.
I’m in Tucson and saying that right now it’s very hot outside would be an understatement. In my workshop, which is the attached 2-car garage, it’s about 100 degrees these days. Actually a tad over 100 right now and a bit under 60% humidity.
Today as I passed in there I noticed that the board was no longer flat but raised about 1/2 inch off the floor on each end, warped. I was bummed and didn’t know what to do. I turned it over, and put my shop stool on top of it. It’s not very heavy and wasn’t enough to push the board down flat unless I sat on it. However, after just about 3 hours like that (just the stool, not me sitting on it), the board just unwarped itself and became mostly flat again.
I just can’t believe how fast this can happen. I guess it’s just too hot in there.
I recently tried a portable swamp cooler. The poor thing couldn’t do anything about the heat (unless I spent my time sitting in front of it) and just leaked all over the place. Gotta be extra tough to woodwork in the summer down here.
Replies
Chuck,
I'd kill for 100 degree weather with 60% relative humidity. I think 80% to 95% RH is the norm here in southern Mississippi. Course that's nothing 3 or 4 showers a day won't cure!
Lee
Well, it's not really 100 degree weather, it's 100 *inside the shop*...Outside it's more...
I would think the putting it on the concrete floor is the biggest issue. Moisture comes up through the colder concrete even if the floor has been sealed. A good rule is to always keep wood off the floor at least 4-6 inches and allow air to alway get to both sided equally.
The direction of curl suggestes that the bottom side absorbed moisture. In general, heat (or cold) has little to do with wood warping.
Thanks for your comments. I also thought that the problem was leaving it on the floor, as that same board has stayed in the workshop for a while on its edge without issue. The rest of the wood is up on the wall without problems, although I'm afraid the excessive heat and dryness might create some checks or make them worse on certain pieces, but maybe not. I've got some long beams that seem to have developed more of them.On the other hand I was really surprised by the small amount of time it took for the board to go back to normal after turning it over.
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