U of S | Mailing List Archive | alt-photo-process-l | Re: which dichromate

Re: which dichromate

On Fri, 9 Oct 2009, Keith Gerling wrote:

Does anyone know a simple method of determining whether a substance is
Potassium vs. Ammonium dichromate?
Mix a batch at the solubility of the ammonium dichromate: (13 grams to 50 cc distilled water) and see if it all goes into solution. If it does, it's ammonium.

If it's potassium, which is only about half as soluble, 50 cc would take only about 6 grams of the chemical.

As for am di being "faster," as I understand it, ammonium dichromate is only "faster" because there's a larger amount of it in a given amount of solution (as above).


I just started using a fresh batch of
what is supposed to be Pottasium dichromate and now I'm getting very bad
results: staining and what looks to be overexposure.  Whatever it is, I am
using a saturated solution.  Isn't Ammonium dichromate "faster"?