John Schmitt wrote:
On Wed, 19 Oct 2005 14:03:07 +0100, Stuart Noble
wrote:


Oxalic acid only really applies to rust stains as it tends to take
out the hydrated oxides of iron.

It seems to be the basis of decking cleaners (a new must-have for the
makeover brigade). Quite what it does, and how, isn't immediately
clear. I've never found it effective as a wood bleach.

It will not as such bleach wood. However, oak (a common deck wood)
stains a dark colour on exposure to iron salts, the tannins in the
oak will react with them. Leave a piece of iron or steel on the deck
and give it a bit of salt spray and you have a deeply rooted stain.
Again the oxalic acid forms a metastable complex which is colourless.
Being metastable, the colour will return in time and require a
further application.

John Schmitt

You must have really pi**ed your parents off.

--
Sir Benjamin Middlethwaite