This may be a silly question and I may have already answered it myself in my head, but I'll ask here in case I'm missing something.
I've got a stack of red oak boards that were milled about three weeks ago. I brought them home, let them sit for about four days and finally got them dusted off and stacked with stickers. The boards are 5/4 boards and the stickers are 4/4 square. My question is the this; today I had to move the stack and found mold on several of the boards in the middle of the stack. Is this the result of not enough air circulation? I moved the stack so that I could get a fan on this stack along with another stack to speed up the drying time. Is the mold something that will ruin the wood, should I be able to clean it off once dry? Is there anything I should be doing now to remove the mold, or just let it dry then clean it off?
I have photos if this helps - I just can't upload from my phone right now.
Any help would be appreciated.
Thanks, Vance
Dead stacking green lumber for 4 days pretty much guarantees trouble. Remove dust and sticker ASAP. Same day is best. Overnight maybe, but I think it's too big a risk. If you just can't get it done the same day, at least throw a few stickers between boards.
Thanks. Oddly, it's only about five of the 24 boards.
There is a very high sugar content right under the bark, so it is not unusual to see a little mild (surface only) when drying is a tiny bit slow.
The fan could be worse than the mold when drying oak. You can ruin the wood if it dries too fast.
For various reasons, if you are seeing mold deep in the middle of the stack, it means you are not getting enough air circulation. Most times, mold in the middle of a red oak stack will lead to sticker stain in the sapwood of the boards, as the heartwood will be much more resistant to stain, although both will grow mold, which is to be avoided. A dusting of surface mold is no big deal, but it indicates a possible bad situation on its heels, i.e. the dreaded sticker stained zebra wood that won't plane out.
A simple trick that has worked for me for years is to space the boards about a finger width to an inch apart to allow the stagnant air in the middle of the pack to "chimney" out, and allow the moisture to escape. Also, moving your stacks to get a nice ambient breeze will help. I had one location that repeatedly sticker stained oak, but moved the stacks about a hundred yards, changed their orientation to the prevailing breeze, and it's been years since I've had a problem with RO. Kind of simple, but a stagnant drying location will lead to problems.
As mentioned, no heavy fans allowed on red oak unless you want to produce a stack of split kindling. If you want to use fans, keep the velocity very low, maybe under a hundred feet per minute. Personally, I never use any fans on oak, too risky.
I'm curious, are the boards you are seeing mold on kind of wide, or mostly sapwood?
Mold and mildew are both fungi. They need warmth, oxygen, food and water to be active. The food for both these is dirt, dust, microorganism in the air. They do not use any of the wood for food except the high sugars right under the bark. Without food in the wood, they do not penetrate the wood. Of course, conditions for their growth are ideal for other fungi, like blue stain.
To control mold and mildew, we eliminate one of the four required elements. We cannot do anything about warmth, oxygen or food (although when edging lumber we usually cut off the Rick sugar-filled sapwood right under (1/100") the bark), so all we can eliminate is water and we do that by rapid drying...low humidity and good air flow within the pile.
Ok?
WOW! What a great bunch of responses. When one joins a forum, it's always a crapshoot as to how the other members respond, even after lurking for a while. So far, I'm pretty impressed with how a new guy is being treated. Thanks!!
On to answering some of the new questions.
Yellowhammer; I am using a fan, but I've learned that with some ash that I dried last fall, the one fan that I'm using works good if i run it for two hours, off for two and back on and so on. I read in a paper from a forestry department, I think VT, that letting the air settle and rest allows for more moisture to wick out and then settle, opposed to circulating all the moisture all the time. The boards are about 10" wide, 1" or 1 1/8" thick and a fair amount of sapwood. This wood, along with some cherry, hickory and poplar are all in my garage, out of the elements. The red oak is stickered with 1'X1' stickers. I've added a photo of what I found upon moving the stack. Again, this was before restacking where the fan could be used. The fan is now in place and on a timer.
Thanks again!!
(https://forestryforum.com/gallery/albums/userpics/43163/IMG_6239.JPG)
A garage has no natural air flow. That is your problem. The only worse place to try and dry green wood is a basement :).
You're right, my garage does not have natural airflow. But I did create it though. The fact that I was able to dry Northern white ash in four months proves that.
Using a part time fan is ok for oak but not ash, maple, cherry, pine, etc. the info you saw about part time fans was likely for thick lumber and maybe in a solar kiln. Run two fans 100%. It should take 30 days maximum for 4/4 & 5/4
Thanks Gene!
We actually brought home the last of this bunch of oak last night. This is what's now in my garage. These photos were taken late last night. The boards will be restacked properly yet today. I need a bigger garage!!
(https://forestryforum.com/gallery/albums/userpics/43163/IMG_6275.JPG)
This is me, patiently waiting on the mill to clear.
(https://forestryforum.com/gallery/albums/userpics/43163/IMG_6283.JPG)
(https://forestryforum.com/gallery/albums/userpics/43163/IMG_6278.JPG)
(https://forestryforum.com/gallery/albums/userpics/43163/IMG_6282.JPG)
Those really wide boards are white oak and are 17-18" wide and just over 9' long. I had everything from last night milled to 5/4.
It's hard form me to tell with my eyesight but are your stickers real thin? Like about 1/2 inch?
Jon
To get me through the night they are. Like I said, the boards will be stacked and stickered properly in a better location within the garage. It was late and I was tired....
Quote from: Vance on May 31, 2016, 09:39:16 PM
You're right, my garage does not have natural airflow. But I did create it though. The fact that I was able to dry Northern white ash in four months proves that.
Is the issue that you have created air flow though the stack, but no air exchange in the shed. The air picks up moisture from the wood, the humidity goes up, and you end up circulating the same humid air though the stack. At some point you need to get rid of the water. Extractor fan or crack a couple of windows open a bit?
Sure it will dry eventually because the shed isn't airtight. But it might be a bit slow for some species?
While the garage is heated as needed and insulated, it's far from air tight. I have an air exchange from the outside to some degree now and can and likely will allow a couple windows to be cracked open and probably one or both garage doors to aid in this. I also have a roof fan that is on a thermostat as well as a bypass switch. That' will start getting a work out once the temps go and stay above 90.
Thanks guys!! I really do appreciate all the input!
So Yellowhammer touched on my original question, and that is what if anything I should do about the mold that has already appeared on the red oak? I really don't want to lose any of this as of the three boards I saw the mold on, two were 8" wide quarter sawn boards.
Add to this dilemma, that additional 400 b/f of red and white oak that I just brought home that I fear may become contaminated if I can't or don't get this under control. I have a couple old squirrel cage fans that I plan on using to keep the airflow moving more efficiently than the one 20" box fan if the general consensus thinks this is best.
Thanks!
Vance
There are two books on line, that tell you options for air drying. They include stacking. Check out AIR DRYING OF LUMBER and DRYING HARDWOOD LUMBER. Both are USDA Forest Service publications.
Basically, you need 3/4" sticks about 16" to 24" apart...use the same spacing all the time, just choose one in this range. You need outside air with the outside temperature and humidity. You need fans that run during the daytime to keep the air moving, although moving quite slowly.
The good news is that mold does not go into the wood, but does indicate slow drying which can encourage other stain inside the wood. A stiff brush will remove mold after drying. In a severe case, mold can be so severe that it blocks air flow, which can be a disaster.