Question
I have recently been asked to saw up some sizable red oak logs. The customer can't get to them right now and wants to wait somewhere between 1 and 3 months to saw them up. The logs are about 36" at the butt, and 42' overall length. I haven't had any experience with red oak at all where I am, and consequently don't know whether or not it will blue stain like others will. She also said that others had told her that while air drying, in a barn or other semi-enclosed area, it smells like vinegar. She is worried that it will smell so badly that she won't be able to live in the adjoining living quarters of the barn. Can anyone help me out with this so that I can relay the message to her?
Thanks to WOODWEB for all of the insights I have gotten in the past. I have learned an awful lot about this profession. I intend to build at least two solar kilns and probably a third and much smaller solar kiln in the upcoming months.
Forum Responses
(Sawing and Drying Forum)
From contributor W:
Regarding the blue stain, are you talking about blue stain that you see in the logs right now or blue stain that appears after sawing? Blue stain in the logs right now means metal you get to cut while sawing the logs. Blue stain that develops on the lumber is a result of the tannic-acid-rich log moisture mixing with the iron of the saw blade. Cooling water enhances this, contributing more moisture to the chemical reaction. The resulting blue/black from this reaction is as deep into the wood relative to how much time the iron and tannic acid were present. The blue resulting from sawing should plane away in one pass. The blue from the nails or fencing in the logs will not plane away. It’s there - that vinegar smell.
Although it may not really matter, what species of red oak are you dealing with? That lovely smell is just part of it. If the logs are from trees that had a certain fungal infection, the lovely smell becomes more like vomit. Again, just part of it. The smell does go away or subsides as it dries and will likely not be smelled in its end use form.
With reference to the smell, you mentioned that it would go away over time as the wood dries. What amount of time would she have to put up with that smell - a month or two, or will it hang around for much longer than that? The wood will be dried in east Texas if that helps any.
I do think the degrade will still happen, but maybe not as bad since the log is off the ground. The bottom half of the log is still sheltered by the top half. The top half is still taking most of the abuse from the sun and drying faster. Warp and twist will still likely occur, but maybe not so bad.
This just came to mind! If the tree was wind thrown with the root plate still intact, the tree is still technically alive and it could, in a sense, be kept on ‘life support’ until you got to it. Water, water, water.
Note that in Texas, it is common to find sapwood in red oak that is 4" wide, so even in a large log like you have, you are talking about a lot of poorly colored lumber. And this outer sapwood lumber will be the clearest too (potentially the most expensive). (If you have 4" wide sapwood on a 36" log, it is like having only a 28" log if you get a lot of stain. I would not want to throw that much wood away.)
From your description, it is possible that some white rot might also develop. Iron tannate stain (or just iron stain) is a reaction of iron and tannic acid. It does not go deep in most cases. It can be quickly removed with oxalic acid (also called wood bleach).
What has not been mentioned is that you may also get gray stain, which is a complex enzymatic oxidation reaction (mainly in the sapwood) where the sugars and starches are oxidized, similar to the browning of an apple that has been cut and exposed to the air. If you have warm weather, it is likely that this gray will permeate the sapwood. Note that it is not fungal.
A log that is still attached to the roots will not degrade much as the bark will prevent any drying. I have never heard of the type of warping (drying defects) that contributor W described from a stored log. Logs are stored at sawmills for months sometimes without such things happening. Any of the logs that are separated from the roots should be end coated to prevent end drying.
The aroma in the barn would easily last for a month or more. In fact, sometimes it may last for many months if there is some bacterially infected wood in the lot.
In this respect, a barn is not the best place for drying oak as there is not enough air flow, so the RH will be too high during the daytime. Air drying under an open shed would be best. If not, then go with what contributors L and S stated.
This is what I think we get a lot of in the pecan we cut here. I have been doing an awful lot of reading about solar kilns and drying in general, and it appears to me that the slower you dry wood until it reaches about 20% MC, the less chance of defects. Which just so happens to go along with what I have learned the hard way about drying some of our woods. I had originally advised against drying outdoors for this very reason. I don't, however, have any experience with oak. I cannot dry pecan outdoors because it just seems to dry too quickly and leave a lot of checking and warping. We place our wood in a shipping container, and leave the doors almost closed until the MC reaches at least 30%, and then open them a little farther until 20%, and then full open (to the south wind) after that. I will have to check on it, but my understanding is that the "barn" is not fully enclosed, but rather has some sort of breezeway in it.
Am I way off base with my thinking or am I reasonably close in assuming that it needs to dry slower until it reaches about 20% MC? Thanks for your help.
