Bleaching...

[ChrisF]

Hiya, looking for some advice/resources/information on bleaching wood.  anyone with good experience out there?

[Les Symonds]

I recently tried an experiment to both ebonise and to bleach different items made from the same piece of dry oak burr. The ebonising was done by scorching. For the bleaching I used ordinary household bleach. I bought a 2 liter tub and poured it into a plastic tray, then (carefully) lowered the wood that I wanted to bleach into it. I'd carried out a few test pieces, and decided that it was best to immerse the oak overnight to get a good depth of penetration. The next day, the oak was removed form the bleach and when the surface had dried off it was lightly sanded, then re-immersed for a few hours to bleach-out any exposed grain from the sanding.
My oak was a very dense piece, yet it bleached well and there certainly was a significant change of colour. I imagine that less-dense materials will need less time in the bleach and that it will achieve a whiter colour, but the results of this test worked well for my needs.



Les

[Bryan Milham]

I know of 2 wood bleaching agents, Oxalic Acid available from liberon, and

Hydrogen Peroxide, available as hair bleach, but be careful, it can be very funny stuff, it's also used as a rocket fuel!

[ChrisF]

Thanks guys, some ideas to play with there.  Sounds like I should be careful with the scorching/bleaching combo though.....

[Paul Hannaby]

The two part wood bleach is quite effective. I think it's hydrogen peroxide and sodium hydroxide.

[Lazurus]

Oxalic acid is cheap as chips of the WWW and great for all sorts of jobs including cleaning GRP PVC etc. Used a lot by the boat industry around here.

[mickdundee]

A bottle of hydrogen peroxide is about a quid at the chemist, but as stated it requires caution. It's oxidising which means it makes things which are already flammable, extremely flammable!

[fuzzyturns]

I've recently bleached a piece of holly with standard household bleach. Worked OK, but with differing degrees of whitening on side grain vs. end grain. The end grain looked like it had sap coming out of it, much darker than the side grain.
As I wasn't quite happy with the results, I left it in quite long, and eventually overcooked it: the bleach started to dissolve the actual fibres, and I had to throw the piece away. I reckon a total exposure of about 24hrs max. for household bleach, probably less on softer timbers.