Removing black stains from oak

[Texas splinter]

I have an oak door that I removd from an old ice box I am refinishing and the lower stile has a large black cloud-shaped stain in the center of it. It looks grey when the wood is stripped, but looks very black whenever it is moistened. (thinner, stain, tung oil, etc.)
Looking on the web, I see that the advice is to use oxicilic (spell?) acid, but I can not find any here in Abilene. I bought some Deck & Fence cleaning stuff made by Behr, it is a concentrate that is designed to be cut with 4 parts of water. It contains 10% Oxicilic acid. Will it take out the stain, used straight? or should I find a source on the web and buy the crystals and mix some full strength?

[cabinetman]

I would first try Trisodium Phosphate (TSP).

If that didn't clear it, try Oxalic Acid. In using any chemicals it's imperative to properly protect yourself and work in a ventilated area.
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[Texas splinter]

When I looked at the TSP and TSP subsitute at Lowes, both labels clearly stated: "Do not use on bare wood..." or words to that effect. And, as I stated, I can't locate a supplier for pure O.A. here in Abilene (The city's new "branding" is "Abilene - Frontiering")
but it is diffucult to get anything here unless it is for raising cattle or farming.

[rnelson0]

I was going to post a similar thread. What I am experiencing is not a particular stain - no defined edges or obvious source of agitation - but more of dark splotches, either from age or dirt. I have sanded down 1/32" on each side and I do not want to sand it any further. I was thinking of using bleach to get the darkness out before I put a stain on it. Since I already have bleach and do not have TSP, would there be a problem with that?

Thanks.

[jlm]

I've found oxalic acid at Home Depot (look in the paint department, I think). The container was labelled just "wood bleach" or something like that, but on closer inspection, it's the oxalic crystals.

The stuff works great on tannin stains on oak (sounds like what you've got). The deck wash might work, but will probably be too weak. I don't see any harm in trying what you have first. If it's not strong enough, you'll just have to get the tougher stuff. Multiple applications of the undiluted deck wash might be enough.

[Texas splinter]

Jim said: "I've found oxalic acid at Home Depot (look in the paint department, I think). The container was labelled just "wood bleach" or something like that, but on closer inspection, it's the oxalic crystals."
Jim: I would love to be able to go to Lowes or HD and get things like that, but here in Abilene, they don't carry anything like that. I was told by the pain expert at Lowes (the store that has been in town the longest) that "...we used to carry stuff like that but I guess it didn't sell enough. We stopped stocking that years ago..." HD is where I was told that the deck cleaner concentrate was "...the closest thing you will find in Abilene to what you want..."

[Texas splinter]

Well, the deck and fence cleaner worked, kind of. After applying it twice a day for several days, it did manage to lighten the water stain enough so that when I put the oil-based stain on, the darker area didn't look too out-of-place. I used "antique oak" gel stain and stained (first coat) all around the dark area. Next day I added a second coat of stain and this time included the darker area, final finish was tung oil.
Mama's happy so I'm happy. ;~)

[Uncle Cracker]

Mama's happy so I'm happy. ;~)

And that's what matters...