Iron Stains in Red Oak

Slabs from a yard tree with a lot of deeply embedded nails have some bad staining. Will bleach help? April 20, 2011

I have recently cut some very nice slabs from a large urban red oak. The tree was riddled with nails and other bits of steel. My center cut hit 3 pieces alone, some as deep as 18" from the bark. So, each slab has a lot of staining. I have read that oxalic acid can neutralize the stains, but how effective is it with really deep stains?

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Forum Responses
(Sawing and Drying Forum)
From Professor Gene Wengert, forum technical advisor:
It is basically a surface treatment.

From contributor D:
Stain that bad, through all the wood, means that board is not much good is for a table top or something that has to have a nice unblemished slab. I would use it for other stuff that is hidden, like braces under tables.

From contributor J:
I would expect oxalic acid to remove the stains shown in the photo. No substitute for trying it out. Just make a water solution and brush it on. Keep adding more until the stain is gone. The gray/black stains should disappear. Each application takes about a minute or so to do its work. Not sure why anything going on below the surface would matter.

From Professor Gene Wengert, forum technical advisor:
Because oxalic acid is a weak bleach, it is important to neutralize or wash off the acid after half a minute or you will bleach the wood grain and it will not look nice. If a strong solution is used, the wood will pink. Another name for oxalic acid is wood bleach (in the store).