Drying question

[OcoeeG]

I am about to start milling up some lumber. My next issue is figuring out how I am going to dry it. Obviously I am going to sticker it and cover it. But I wanted to try an improvised solar kiln for little to no extra money. Tell me what you think.

I have a bunch of old barn roofing tin laying around. What if I stacked and stickered my stuff, weighed it down then made a roof of that tin painted black. Around the pile I would wrap black 6 mil plastic to keep the heat in. I figure that would make for a pretty warm environment even in the winter if put int a sunny spot. I realize ventilation is one of the most important aspects of the drying process. I haven't exactly figured out how I will pull that warm air down through my stack. Does any one think this would be better than just a regular air drying set-up.

What says ye?

 

[BlueRider]

The first log I ever milled was a 36" oak. it got too hot too soon after milling and I lost all of it. I have been more concerned with the wood drying too quickly than I have been about it taking too long. Once you get a few logs dry you will not be in as much hurry and a kiln will end up on the permenant back burner.

 

[Mike Van]

Wrapping plastic around freshsawn lumber is not a good idea, you will have mold all over everything. There's load of info out there on solar kilns, etc - I'd look it up as these people have done the trial & error part already.

 

[AndyR]

Wrapping plastic around freshsawn lumber is not a good idea, you will have mold all over everything. There's load of info out there on solar kilns, etc - I'd look it up as these people have done the trial & error part already.

I'll second that.
I ended up with mold growing on my stack of walnut and that was in a garage with a fan blowing. I had to take the entire stack down and spray dilute 50/50 clorox on all of it. It makes me think that stacked outside with a cover and weight on top is best (until it's dry to the touch at least).

 

[BobL]

If you only cover with plastic, cover the timber like this.

A couple of layer of shade cloth or 3 layers of hessian also works for a while.

 

[irishcountry]

I've heard that the first stage of drying is the most important getting it down to at least 20% before trying to dry it further. A band sawmiller told me that if you let it air dry down to 20% first then put it in a hotter enviroment you will not get the bad warpage that you would sticking it directly in a hot enviroment. I put 1 fresh red oak board in my smallest greenhouse in June/July (HOT) and it dried really quick but its a mess and firewood now. I just wanted to see how quick I could get it bone dry and it did work but I would have been upset if I put it all in there!! The stack I have in my garage from this summer will go in there this next year with the fans on and doors open to get it down where its totally stable (at least I hope) A moisture meter is on my list of things to get soon!! have fun irishcountry

 

[oldsaw]

The cover part is a good idea, but skip the plastic. As has been pointed out, you need airflow to get rid of moisture, but you don't want to lose it too fast. Being a suburban miller, who typically does small batches at a time, I usually stack the boards in my garage and have a box fan on one side blowing indirectly on low, and a dehumidifier in one corner of the garage. Once the initial moisture is down, I'll just run the dehumidifier. When the dehumidifier stops pulling much moisture, then I'll just let it sit for a while longer.

Unfortunately, I don't have a good spot in my back yard to stack lumber. But the most I ever had at one time was 400bft of mixed oak and walnut, and it fit in my garage. Kept that dehumidifier working hard for a while. Amazing how much water wet lumber carries. When the stacks are that big, it doesn't hurt to rotate the stack during the process. I had very little problem with warping, and the ones that did cause a problem came from a log with an off-centered pith. Probably would have warped anyway.

Mark

 

[dustytools]

Try doing a google search on dehumidification kilns. Ive read about people building them relatively cheap with portable AC units. Havent done it myself but I did a little research on it a couple of years ago.

 

[Backwoods]

I take wood to a local kiln from time to time, and the wood has to be air dried for at least a month before he will allow it in his kiln. You just get to much down grade if you are not patient. As far a basic solar kiln just think green house with lots of airflow. Use baffles to allow the air to move thru the stack not over and around the stack. Said another way think of the dog that just came home from the vet with one of those big V shaped head collars. The dogs head is the fan and the wide opening is the side if the stack of wood. Move lots of air thru the stack of wood. No heat necessary.