Re: bichromate gum

["Christina Z. Anderson" <zphoto@montana.net>]

Don,
I never buy reagent grade chemicals and do just fine.  I also have used all 
three dichromates and they're all fine except sodium is sooo saturatable 
that you can mix it over 100% and get a honey like consistency.

Speaking of the painterly approach to gum, one of the highlights of my stay 
at George Eastman House was seeing prints that had the brushed on colors as 
you say.  One guy did the base exposure in a neutral color (not black, but a 
greyish putty color mixed from different watercolors) and exposed a lightly 
pigmented and long exposure layer first to get all the pix detail, then came 
back in and brushed different colors on in different areas.  It was quite 
fun.  I wonder if you couldn't try to do that, and paint your dichromate 
only layer on top of the putty layer, below and then brush on the different 
colors hither and thither and then expose?
Chris
----- Original Message ----- 
From: "Don Sweet" <don@sweetlegal.co.nz>
To: <alt-photo-process-l@usask.ca>
Sent: Thursday, July 10, 2008 6:48 PM
Subject: Re: bichromate gum


> Thanks to Sam, Christina and Judy for the helpful replies.
>
> Speaking of chemical purity, my dichromate isn't exactly reagent grade - 
> it
> is sold  as "sodium potassium dichromate" by the kilogram for use as a
> pottery glaze.  That seems to be the only way to buy it in New Zealand 
> now.
> I recently acquired some photo chemicals from an old hoarder which 
> included
> a 1oz bottle of pot dichromate with a pharmacist's logo on the label and a
> price dating back to before we converted to decimal currency (1967) - the
> contents had formed a single crystal  Obviously in those days you could 
> buy
> stuff like that over the counter, but now we have an international
> bureaucratic network dedicated to eliminating such hazards now (also
> removing Portriga Rapid paper and mercury lightmeter batteries, and
> replacing inert aerosol propellants with explosive ones).
>
> One of the advantages that I thought the "bichromate first" technique 
> might
> offer is the opportunity to take a more painterly approach to the 
> colouring
> step - e.g. use more colours, follow the image a bit, and leave some 
> blanks.
> Does that make sense?
>
> Don Sweet