Acetone stains on wood.

[Dan S. MacAbre]

I discovered that acetone is rather good at getting rid of the paint that lingers in wood grain after the more heavy-duty stripping, which I find always leaves a bit behind. So I now have nice (if slightly distressed-looking) bare wood window sills again. Unfortunately, I left some tools on there overnight, and they have left a black mark (looking a bit like exposed photographic paper) where they contacted. Is this a known phenomenon? It would seem to be a good wood stain. And (more to the point), before I get the sandpaper out, is there a non-destructive way to neutralise it?

[Brian Gaff]

If you dry outwood, then it sucks up anything around back into the bare grain. Brian

[Chris Hogg]

Not sure it's got anything directly to do with the acetone, but iron (e.g. nails, or in your case, tools) is notorious for staining wood, especially oak. It's the tannin in the wood that reacts with the iron to give a black stain, presumably some sort of iron tannate. IIRC moisture is involved somewhere; did it rain, or was there a heavy dew overnight? I expect you'll tell me they were indoors! Don't know a solution. Perhaps spread some iron filings over the rest of the cill, and at least get it all a uniform colour!

[Dan S. MacAbre]

I forgot to mention that the stains are jet black, and the 'image' is very sharp. Like someone drew a line with a ruler and a black felt-tip pen. It doesn't have the look of something that would come from within the wood itself.

Brian Gaff wrote:

[John Rumm]

Yup, I would agree - it sounds like a classic case of iron staining...

Furniture restorers will usually use oxalic acid (aka wood bleach) crystals dissolved in water. You apply with a sponge and using a stiff brush scrub into the grain a bit, then leave to dry. You may need a few applications. Wash down with clean water once done.

One of many examples:

(very good channel for anyone doing work on real furniture)

[The Natural Philosopher]

bleach works - or caustic soda.

[Malcolm Race]

Please take care if using it. It is classified as a poison althousg in relatively high doses (Wikipedia suggests around 30g (1oz) for an adult.

Malcolm

[newshound]

Beat me to it. And John has already posted the fix!

[newshound]

Also present in raw rhubarb. Not sure how much you would need to prepare a suitable bleach though.

The stain probably won't be very deep, so sanding could be another option.

[John Rumm]

Yup, classic iron and tannin.

(bit like the inky black staining sludge you get out of central heating systems)

You can even use it deliberately as a way of staining and darkening wood. Wire wool and vinegar is one popular technique:

[Dan S. MacAbre]

Okay, that seems like the answer. It /is/ indoors, but maybe the acetone had some water in it (it is described as 98%). The marks are left by the edge of one of those triangular paint-stripping things, and the bottom of a nitromors can, so there is going to be some iron in there. I'll probably just sand it out - it will add to the distressed look that the missus currently likes.

[Andrew]

Hydrogen Peroxide, part of 2-part wood bleach would do it. Goes well with Acetone, by all accounts :-).

[Andrew]

Only rhubarb leaves contain oxalic acid.

[Chris Hogg]

The stems also contain oxalic acid, but not enough to cause problems.