Blue stain on pecan

[NCDiesel]

As some of you may have read on the events forum, we had a great sawmill weekend at my place a few weekends ago.    One of the by-products was several great 2" slabs of pecan crotch.

Excited, I moved them into my shop, opened the windows, and stacked them 4" off the floor with 1" dry pine stickers between them.

I am getting blue stain on them  )-:  This was not present (at least not to the eye) when they were sawn.

I have never seen blue stain develop after sawing before.   I have seen lots of logs with it, but never in boards after the fact.   Have I just been lucky and this is common?  Or a I unlucky and this is really weird and uncommon?

I really don't understand.   My shop is very dry, has 8 big windows for ventilation and the air should have been moving through the stack fairly well.

I hope they aren't ruined.  Thanks in advance for any idea, thoughts, pointers, etc

[GeneWengert-WoodDoc]

Although blue stain can be caused by a blue-colored fungus that really grows fast when drying is slow, there is also a blueish grey stain in pecan that is caused by the oxidation of starches and / or sugars in the wood.  This develops because the logs were allowed to sit in the woods too long, the lumber was not dried promptly and the lumber was not dried fast enough.  This oxidation stain is common in hickory.  We need a lot of air across the pile and a fairly low humidity, but not too low that cracks develop.  The surface color can be brightened by using wood bleach (oxalic acid), but it is only a surface treatment.

[WDH]

I have had problems with gray stain in pecan after sawing.  Now, I use fans to keep air moving between the layers to retard the reaction.  It is also bad in maple, and I have seen it in hackberry, too. 

[NCDiesel]

Update:  a day or two after this post I pulled the slabs (heavy suckers) and found regular mold - like the kind you would see in a damp basement.   So I enlarged the stickers I was using to two inches and turned on a fan.

I think the problem was not air flow - I think it was my use of one inch stickers.   I never stacked such wide boards before and I think 1" stickers just can't ventilate green, wet, wide, 2" thick slabs fast enough.  I think my ventilation would have been sufficient if there would have been less restriction.

We'll see how it goes.   

[POSTON WIDEHEAD]

Certain soaps, etc. that we mix with our water in the mills lube system will mix with the sawdust as we saw. This will give different color stains on our boards / slabs also.

[LeeB]

NCD, if you have mold, you have an airflow issue. Increasing stickers from 1" thick to 2" thick would give you more airflow. How you have the stack oriented to the predominate wind direction will also make a difference. Turn the stack so the wind blows through it from side to side.