DIYbanter - View Single Post

(Pete) wrote in message ...
Will ammonia turn new pine gray.

No.

If you want a grey on pine, try an iron acetate mix. This is very
easy to make, and less unpleasant to work with than ammonia.

Take a jar of strong vinegar. You can just use an empty pickle jar and
contents, but clean pickling vinegar is cheap. IMPORTANT - Knock a
couple of holes in the metal lid as a gas vent - this mixture
outgasses a little, and you don't want a glass shrapnel bomb in the
workshop.

Throw in a little clean iron. Steel wool is good, and reacts quickly.
You can use old woodscrews too. Then place a big heavy nut or
something on top to weight it down. Make sure that there's no wire
wool poking above the surface of the liquid.

Leave it for a week and ignore it. You should then have a dingy
grey/black solution. Any red or brown colour is bad, as this will give
a rusty brown stain on the timber (you probably had the wire wool
exposed to the air). The mixture keeps for a few weeks, but throw it
away after 3 months, or if it discolours. Taking the iron out improves
keeping.

To use this, just wipe it over your timber. Leave it for 20 minutes or
so, then wash off. Sometimes a mere spot of detergent helps to wet the
surface.

It works best on tannin-rich timbers like oak. I've no idea what the
chemistry is - clearly the old "iron gall ink" recipe is involved, a
reaction that produces iron tannates. However this recipe also works
on some timbers that are practically tannin-free, including softwoods.
It tends to grey rather than black, but there's definitely a colouring
action (and not just a pigment effect) I can't promise this will work
on your timber, but it's certainly worth the experiment.

I'd also be interested to find out what the chemistry is here.