What might have caused this staining on red oak?

[Delawhere Jack]

Milled oak for a client in July 2014. He recently broke down several stickered stacks. One stack had some rust colored stain on the boards in some layers. The wood has been air drying for almost 1 1/2 years. The stack was covered in the same manner as other stacks that had no staining.

I've never seen staining with color like this. Mouse urine? Any thoughts?



 

Thanks,
JC

[beenthere]

Looks (to me) like there was a water leak in his cover on that pile.

[isawlogs]

  Sure looks like water stain to me also!

[Darrel]

Water stain

[kelLOGg]

I had some oak stain not quite that dramatic and I attributed to water. It planed out leaving no trace of it.
Bob

[ellmoe]

Ditto, water.

[WDH]

Mine like that always planes out on the first pass.

[beenthere]

Now would be good to know (but not real important) how the cover on this stack was different and leaked, as well as what material the cover was made.
Suspect maybe used metal roofing that was a bit rusty.

[GeneWengert-WoodDoc]

Here is a bit of technical explanation.  We have partly dried wood and it gets wet.  The water dissolves a bit of the chemicals in the wood.  The wet wood is dried slowly, so the water with the dissolved chemicals has time to move to the surface as a liquid.  At the surface, the water evaporates leaving the water soluble chemicals behind.  This goes on for a while, giving us a concentration of these water soluble chemicals right on the surface.  Due to the concentration and probably some oxidation, the color darkens.

So, part of this is accentuated by high water absorption by some parts of the wood due to rain or snow intrusion into the pile (or mice) and due to characteristics of the wood itself. We also see this often with eastern white pine that is dried too slowly...there is no external source of water, but just real slow drying and variable drying.  Bacteria lily infected wood also makes this more likely.

Because this is a surface effect, it will plane off easily.

Note that iron stain would be much darker.