Ferric Chloride for Aging Wood
Ferric Chloride is a strong chemical and should be approached with caution. March 12, 2015
I've been asked to quote a job in VG fir where all the exposed wood is to be washed with ferric chloride prior to be clear finished. I presume the ferric chloride wash will turn the wood grey. Has anyone performed this treatment? Is there anything to look out for, specific hazards beyond wearing gloves and a respirator? Does the wash need to be neutralized? Is there any reaction with finishes placed over the top? Are there any alternative treatments that would give the same results that I should consider?
Ferric chloride is a compound that is used to etch metal for intaglio printing. It is nasty and can eat through your hand or a sheet of metal in no time. It is highly corrosive and acidic and gives off a lot of heat when added to water. I assume it is being used to burn off the softer wood in the fir. To neutralize you have to use lots of water and some baking soda and donít let it splash on you. Better read up on it a bit.
From contributor R:
Iron acetate is what has been used for a hundred years to darken wood. Both Fe(II) and Fe(III) Chlorides are overkill for what you are doing. You can even make your own Fe-Acetate with some steel wool in vinegar or other weak acid.
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