Ammoniun vs. Potassium Dichromates

TERRY KING (KINGNAPOLEONPHOTO@compuserve.com)
Sun, 18 Jan 1998 15:33:57 -0500

Message text written by FotoDave
>Does anyone have any relative speed comparison between this 2 dichromates.
I
expose my gum prints with pot. for about 20 mins. I am wondering about how
much it can be faster with ammonium. Just a rough estimate would be fine.
Thanks a lot!
<

Dave

It depends upon the strength of the solution you use. If you use a
saturated solution exposures for the ammonium should, in theory, be about
one third of those for the potassium. I went over to Gloy at the same time
as I adopted the ammonium salt and I changed my technique completely so
that I now use about the same exposures for the two but use mechanical
development as the 'gum' seems to be able to stand up to it. The result is
far more cointrol over the final print which is what gum is about anyway.

Terry