i’ve been charged with veneering and finsihing a footboard to match a cherry bedroom set. i recognized the effect on the existing pieces as having been bichromated. so to reproduce that effect i’m using bichromate myself.
here’s my question: i know how to keep stains from splotching on cherry, but not bichromate. what should i pretreat with that won’t interfere with the bichromate reaction?
Replies
Search this forum for "potassium dichromate" & review. I never pretreat before using it, and suspect that pretreatment might cause splotchy results. Repeat application & rinses until you reach the color needed to match the existing parts. I normally allow the rinsed surface to dry thoroughly (even several days), and steel-wool (0000) lightly before finishing with an oil based varnish or lacquer.
John in Texas
repeat applications, i have the stuff thinned out to the color i need right now, so i should thin it further. cherry tends to blotch up with stains, chemical treatments, this should take care of that blotching?
Sorry to be so long getting back into this ... Pot. Dichromate brings about a chemical reaction within various woods, and in my experience, blotching, as you often see with stains and dies, does not occur. The chemical should be orange or yellow, and must be kept from tiny people who might drink it as OJ or Tange, by mistake. This is most often fatal. This is nasty stuff, often avoided by lots of woodworkers for that reason.
You must begin with a virgin surface on the wood, not sealed nor filled. Evenly sanded, raise the grain with water (yes, even with cherry or maple), sand lightly with sharp paper or steel wool several times, touch the wood as little as possible to avoid contamination. It's not reversible, so you might have to use multiple applications as you creep toward the final shade. Keep in mind, it will continue to darken or lighten (as natural woods often will) when exposed to light.
John in Texas
Hey E,
I've jumped on this topic before, so I hope everyone will excuse me but, please consider carefully whether you should use potassium dichromate.
K2Cr2O7 is very dangerous, and because of the chromium content (35.36%) it's a persistant and difficult environmental contaminant to clean up.
As an example, it is a class 4 carcinogen, and yet gasoline is only rated as a class 3 explosive.
There are alternatives available that will darken cherry just as well, and with the same effect. I use ordinarly sodium hydroxide (lye), but others have had success with washing soda.
If you won't consider your health, and that of those in your shop, consider the environmental effects, or the cost of proper disposal.
Tom
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