Removing black stain from stock

[daveboy]

Recently acquired a Krag carbine. The stock has been sanded (removing all markings), there is a black stained area on it, and it has had a glossy finish applied (probably varnish). I removed the varnish last night and have a pretty nice piece of wood, except for that stain. I have tried paint stripper, turpentine, lacquer thinner, and purple power. No luck. Anyone have any idea what this is and how to get it out?

Thanks
daveboy

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[Chuckindenver]

looks like sap...doubt anything will remove that from the stock.

[Aragorn243]

The location is very odd.

It looks similar to black staining from contact with metal parts and water (rust?).

I have never tried this before and do not know if it would even work on wood but lemon juice and sunshine will remove rust stains from other items. I have used this on fabric materials. I'd try experimenting in the barrel channel to make sure it doesn't hurt the wood. Never left a mark on the fabric, the rust just disappears as the juice dries. I used that concentrated stuff that comes in the lemon shaped plastic containers you should be able to get at most supermarkets. It has to dry in direct sunlight for it to work.

[Patrick Chadwick]

For iron-based stains on wood, try oxalic acid.

[Claven2]

nitric acid will also dissolve any iron stain. You need to neutralize any acid application with baking soda in water solution afterward though.

[daveboy]

Like the other poster stated, it is hard for me to believe that it is rust stain because of the location...far away from an metal. Chuck might be right, but it doesn't look like sap either. Who knows. If I can minimize the look of it I will let you know what I did. Thanks for the replies.

daveboy

[Aragorn243]

It could have gotten the rust transfer stain from an object stored next to it.

Another possibility is that it is a heat scorch mark. Didn't think of that earlier but on looking at it again, it could be a possibility. Probably only way to get rid of that would be to sand it even further.

[HOOKED ON HISTORY]

Thinking out loud hear. How about diluted bleach?

[Aragorn243]

I have an old stock sitting around that had some black staining on it, most likely rust as it was concentrated near the butt plate but there were other spots higher up. Wood bleach took it right off. Used two coatings and then washed it down. Active ingredient is oxalic acid as Patrick suggested.

[us019255]

Oxalic Acid is the thing to try. Does not harm wood. Works best if it is applied HOT. Simply brush on and let work. Use rubber gloves if you value the skin on hands. Rinse well later. A Sodium Bicarbonate (baking soda) rinse, followed by a water rinse will help.

Will raise grain, but no problem as stock has already been sanded. My first house's wooden windows had not been varnished in the 15 years since it was built. Lots of stains that looked like that. Oxalic acid wood bleach took them out. By the way, do not eat the Oxalic Acid, it will wreck your kidneys if you ingest a bunch. (A little is OK, it is found in Rhubarb. So you don't have to be fanatical to avoid contact, just don't eat and wash hands.)

While not a firearm restorer, I have slept at a Holiday Inn and have a PhD in Chemistry.