need to know effects of temp on drying?

[hdtech]

I'm needing to know how much if any outside air temp has any effect on how wood dries? here in texas the last few weeks have had a lot of variation in temp. it has literally gone from a daytime high of 86 to an overnight low in the low 40's. I have just gone and checked on the boards I had cut 3-4 weeks ago and many of them show some serious splitting the whole length of the board. here's a couple pics showing what I'm asking about. they are close up to show detail. but the splits are the the full length.

 

[TPA]

Hello from Lufkin!

The higher the temperature the more moisture air will hold. If the temperature is high and the humidity is fairly low like we have been having, it can pull moisture off fairly quickly.

It looks like you are trying to dry oak. Oak will check very badly if milled soon after falling. I just got started milling myself, and I found out about oak ahead of time, so I tested a couple of things. I had a couple of oak logs, so I let them dry for a year before milling them. I gave the wood away to a family member who had a good use for it, but so far the checking has been minimal after milling. The drought 2 years ago has left a lot of standing dead oak, and so far I have only milled one of those, but I have another one waiting. There has been absolutely no checking from that wood because it was mostly done drying.

I've heard others say that you will want to dry oak as slowly as possible and expect to lose much of the surface to cracks. Walnut is better behaved, and I think I heard the same of cedar.

...Oh and have some East Texas rep!

 

[flashhole]

opcorn: Just getting started myself so I'd like to see the responses. I have a covered area at the barn I may use to set the milled wood to dry. Not temp controlled at all. I will be doing a mix of hard wood and hemlock. The plan is to use the hemlock to build a shelter for the horses. I will be milling storm blow-down trees that have been in place a couple of years.

Does it slow the drying process to cover the milled wood with a tarp?

 

[Dave Boyt]

Temperature, relative humidity, and air movement are all important. Air at 25% relative humidity has the same drying effect regardless of temperature, though moisture will move through wood more quickly at higher temperatures, which helps reduce surface checking. Movement of air through the stack is important. If the tarp covers the entire stack, it will just trap the moisture in the stack. It is better to just cover the top of the stack with metal roofing material so that the air can circulate through all layers. The best way to be sure what the wood is doing is to use a moisture meter. The Forest Products lab has a good guide to air drying wood.

 

[Sawyer Rob]

Hello from Lufkin!
Oak will check very badly if milled soon after falling.

I hope you don't think all sawyers leave their oak logs lieing around (degradeing) for a year or two before milling...

The secret is to control how fast the lumber dries, NOT to leave the logs lay around for a year!

SR

 

[Mahindra123]

In my experience, the greener the wood, the easier it cuts. In log form, a year is not really going to make any difference as far as the wood drying out anyway except the ends. No matter what area of the country that you are trying to air dry your wood, you can't control the heat nor the humidity. All you can control is direct exposure to the sun and for that I would recommend a shed with a roof and sides. To me - air dried means a 3 year process of slow dehumidification of the lumber. Anyway - that's what it is here in Wisconsin. Make sure you sticker every layer, get plenty of weight on top of the pile to eliminate any warpage, pile your boards tightly side to side on a layer. In 20 years, I've never had one board split or warp. If I need 8' boards, I saw 8 1/2' boards and at the end of 3 years, I trim 3' off each end to get rid of the unavoidable end checking. Don't cover a pile to the point it cannot breathe. Then you have mold problems and wood discoloration. If you see checking in your shed down in Texas, you best start closing up some holes because the wood is still drying too darn fast. In reality. you fellas are almost working with the intricacies of a kiln and that's almost rocket science. Also, make sure the base where you stack the wood is perfectly flat. If it's uneven, that will telegraph thru the entire pile and every board will come out warped just as the base you stacked it on. Good luck!