Staining wood

I have a wooden mantelpiece, bought from our local charity shop - looks quite 1930s, and put together similarly to the one I discarded, which was 1935. This current one has been stripped, and the wood quite a greyish colour (oak? - certainly heavy enough). I like it's colour well enough, but it won't match any of the other wood in our room, once we've finished decorating.

I'm thinking of staining the wood, but not in a wood colour. I fancy something quite subtle and transparent, so much of the original character of the wood is retained. I'm considering using artists watercolour, and have been looking online as to how this might be carried out. I had thought to use it as an artist would lay a wash - so wet the base surface (the wood) and apply the very dilute watercolour while still damp, to prevent hard edged marks.

What I have read suggests using white vinegar or alcohol, but doesn't say why. I will probably experiment on scrap wood, and then on the back of the piece, but if any one has ideas or experience of something similar, I would be very interested to hear about it.

Once coloured, I am intending to use a liming wax to finish, which will take the colour back somewhat.

This is not something I have done much of I'm afraid; I tend to go for natural wood finishes - normal wood stains usually look fake and blotchy to me - at least when I apply them. What sort of colour are you looking for ?

I have heard people talk about "milk paint" for applying subtle colour. You could see what Google finds. It is at least all natural and eco; and allegedly doesn't smell rancid when dry

As for using water, I can see a couple of pitfalls. One is the tendency of water to lift the grain - the fibres swell, leavimg a rough finsh when dry. You might be able to sand it gently without removing the colour. The other issue, if it is oak, is to keep anything containing iron away from it when wet. Especially if vinegar is in the mix. The tannins in the oak may react with the iron and produce black stains.