Spray slabs for mold or just stack it?

[Blue42]

I have some black mold on the faces of a few 28" chestnut oak slabs. Should I worry about buying and spraying a mold killer before stacking it? I am going to hit all of it with a preventative treatment of boracare anyway, because there are plenty of powderpost beetles in my woods and they already are in the outside half inch to an inch of the wood.
I was about to spray it and stack it today but thought maybe I'd better make sure the mold dies.

 

[Blue42]

Anyone spray mold killer on slabs that have some spots, or just stack it and sand it off later?

 

[Bmac]

Seems like a lot of mold qyestions/problems lately on here.

But, on to your question. Sure you could spray with some 3 to 1 water to bleach to kill the mold, or you could sand it off later. To have a little surface mold is typically not a big deal and once the wood gets dry enough the mold growth stops. I will caution you about stickers, make sure you are using dry stickers or you will likely get sticker stain.

On to the bigger issue of avoiding mold, which as I stated earlier is a reoccurring theme here. When you mill, endseal and stack your lumber with stickers immediately. No dead stacking for a few weeks or days after milling, you will get mold everytime. Always stack where you have good air flow (not in a basement or garage unless you plan to setup fans) and cover just the top of the stack with plywood or roofing material. Never wrap the stack in a tarp. Good air flow is key to preventing mold. Milling in the colder months helps a lot too as the cooler temps inhibit mold growth and you'll get enough drying that when the warmer weather comes your wood will be dry enough that mold can't grow. Always use dry stickers or you will get sticker stain, which is mold/fungi growth that goes deeper into the wood and can not be planed out.

Study the principles behind air drying wood, there are a lot of sources out there. Always expect some twisting, cracking and splitting. The wood always looks the best right off of the mill, what you have after it's dried is always more defects than you thought off the mill.

Some resources;
https://www.fpl.fs.fed.us/documnts/fplgtr/fplgtr117.pdfhttps://www.woodcraft.com/blog_entr...t-stock-into-a-cash-crop-of-woodworking-woods

 

[Mad Professor]

A good use for EAB killed ash is stickers. It is already dry and you won't have stain problems either.

I air dry outside, and get the stacks well supported off the ground, sticker every ~18" and weight and cover the top. I use corregated plastic plastic roofing for covers, metal may give you stain.

If possible fell trees when dormant/not much moisture, mill, and stack/sticker as soon as milled

 

[Blue42]

Appreciate it. I guess I'll just go on and stack it.

I wonder about drying too fast without covering the wood at all after it's cut. I have checking all over the face of multiple slabs even though they weren't in the sun. And it is high humidity in the mid Atlantic in the summer. I have put a plastic sheet over them for a couple weeks to slow the initial drying, hoping to prevent the checking. But mold is the downside of that. Maybe the sheet doesn't work either. Don't know. Just want to try something.

 

[Bmac]

Ok, I see now, you had everything stacked and stickered, started getting some checking, then tried to slow done drying and developed some mold, is that correct?

I can see you are probably thinking you can't win for losing. Well I'm not far from you and being in the Mid Atlantic region also I know how humid it's been.

Here are a few thoughts on what's going on. First, oak is notoriously hard to dry and it is prone to checking. You really want to dry oak slowly and in a controlled manner. Other woods are definitely more forgiving than oak. Milling wood, esp oak, in late fall or winter gives you an ideal environment to start the drying of the wood in a gentle way, and this will help a lot in avoiding checks and mold. The cooler temps that time of year slow the drying down and, as a plus, inhibit mold formation. We've had a few tornados go thru our area this summer, I was able to score some logs from the clean up. Those logs are waiting patiently to be milled this Dec. They have had their ends sealed and are sitting on my property.

The hotter temps of the summer or late summer dry the wood more quickly even though it's humid. The hotter temps also facilitate mold growth. Now if your wood has had a few months of gentle drying in cooler temps, this eliminates a lot of problems, esp when you are dealing with oak.

Also as a plus, the cooler temps are easier on your saw, saws cool done a lot faster when it's 25 degrees out, and it's a lot easier on you, milling in 80 degree temps is no fun.

 

[WI_Hedgehog]

Stickers & Blocking 101: How to Stack & Dry Lumber
^^^ click to read ^^^

 

[Mad Professor]

Placing covered stickered piles of hardwood in the shade will help with slowing down drying . If you have an area under some trees that works good, as when leaves fall the pile will be in the sun again and drying can proceed slowly.

As mentioned ^ best time to mill is when the cool weather hits in the fall

 

[Blue42]

Yes, that's pretty much it. I covered them to slow the drying and prevent checking, but then got mold. I had not sprayed these though. The boracare might have prevented the mold some. Although it's the regular boracare without the mold killer additive, so I dont know how effective it is in preventing mold.
I had assumed the drier weather in cold months would only dry it faster and make checking worse. Glad to learn that isn't true.
Also did not know that oak was more prone to checking.
I've also had a sweetgum down for about a year. Off the ground, leaning on a sycamore that also fell. I will get to that this fall also.

 

[Bmac]

White Oak is tougher to dry than Red Oak because of the tyloses. https://www.sciencedirect.com/topics/agricultural-and-biological-sciences/tyloses
White Oak is a wood that you can use outside, for barrels and for shipmaking. The tyloses present in the wood block water movement, making White Oak resistant to water movement (somewhat watertight), hence making it harder to dry. With checking it occurs because the surface dries faster than the core, the surface shrinks as a result but the core does not and that creates the small cracks or surface checking. White Oak needs to be dried slowly because of this.

As for drying and temps, the temp is a big factor in drying rate. True the air is drier in the winter months but the cooler temps slow drying down faster than the dry air can make up for. It's vice versa for warmer months, the heat spends up drying and does it faster than the humid air can slow it up. You will end up with about 12-15% moisture content with completely air dried wood in our humid Mid-Atlantic region. So any moisture content in the wood above that will come down and does it more quickly in the warmer months. Finally to bring this point home, our Mid-Atlantic winters often mean mud if our temps aren't below freezing. In the summer you can get a ton of rain and the warm temps dry the ground out pretty quickly, but in the winter it seems to take days for the ground to dry out.

Sweetgum can be a pretty wood, but be aware it is notorious for warping and twisting. Very difficult wood to dry without this happening. Try weighting down you piles as much as possible but still expect some degradation.

Milling Sycamore is pretty interesting, esp if quartersawn. Quartersawn Sycamore if very pretty wood, wish I had some to work with. I guess I'll just need to settle with my Walnut and Cherry.