Bleaching timber

[Neil Schulz]

I wish to whiten a small quantity of pine timber for use in a one off intarsia project I am working on. Could anyone please help with some hints on what to do and how to go about it.

[ubeaut]

G'day Neil - There are a number of bleaching methods including using ordinary household bleach. You can also use a mixture of peroxide with full strength ammonia, however it isn't very user friendly, and it is rather toxic.

The most common bleach for use on timber is Oxalic Acid.

The following is taken directly from "A Polishers Handbook"

Oxalic acid is purchased in crystal form from your chemist, paint supplier or hardware shop. The crystals are dissolved in water that has just boiled, add crystals until you get a saturate, ie. no more of the crystals will dissolve. This solution is applied hot and left on until the desired result is attained. It is then neutralized by washing down with vinegar. When dry, sand and you are ready to continue with staining, polishing, etc.

WARNING
Oxalic Acid is toxic. It will not harm skin if washed off immediately. It is a good idea to wear rubber gloves when using it and do not breathe the fumes. Use outdoors or in a well ventilated room preferably with an exhaust fan.

Bleach works best on timber that is spotlessly clean and whilst sanding the surface does a pretty good job of this it is still not cleaning the wood of chemical and other impurities. This is best done by washing the timber down with lye (caustic soda). Dissolve 8 ounces of lye in 1 gallon of water (as hot as you can handle) then wash down the area you intend to bleach with the aid of a scrubbing brush. Wash off the dirty lye with clean running water, until the water runs crystal-clear, then sponge off the excess and let the wood dry. The surface is now ready to be bleached.

DANGER
Lye (Caustic Soda) is Toxic and Harmful to the skin. Always Wear heavy rubber gloves and eye protection. If splashed on skin wash off immediately with vinegar or flush with water and no harm will be done. Do not breathe the fumes. Use outdoors.

Hope this is of some help.

Cheers - Neil

PS See you in Sydney.