From: Eric Neilsen (e.neilsen@worldnet.att.net)
Date: 03/03/03-08:00:58 PM Z
It is written in some literature that a recommended coating has more
platinum and palladium than ferric. This may be for several reasons,
but if mixed properly your mixture should be equal molar when coating.
Eric Neilsen Photography
4101 Commerce Street
Suite 9
Dallas, TX 75226
http://e.neilsen.home.att.net
http://ericneilsenphotography.com
-----Original Message-----
From: Christina Z. Anderson [mailto:zphoto@montana.net]
Sent: Monday, March 03, 2003 2:16 PM
To: Alt Photo List
Subject: platinum questions
Hi list,
I'm finally finishing up all my reading on alt I ever wanted to do
in
my lifetime, and platinum is way over my head. When I pt/pd printed 5
yr
ago I just winged it, you know? So I really need your advice, as the
books
are SOOOO different!
Questions (please excuse my lack of expertise):
1. Why do most people use a bit more of the metal salts than the parts
A/B
combination? e.g.44/46 drops Part A+B/Part C instead of 44/44?
2. Why does a line of demarcation occur with developing if you don't
submerge the print in the developer evenly, if it is a develop- to-
completion process?
3. I am getting so screwed up by the different proportions of chemicals
in
the developers and clears. Is it really that variably OK?
And, for instance, you chemists correct my math: if you are using
30g
of EDTA in 750ml of water, that is a 4% solution, correct? So why does
one
book call that an 8% solution? Why does this same book say a 1%
hydrochoric
acid solution is 1/2 oz HCL to 1 qt water--isn't that a 5.55% solution?
If
the HCL is 37%. What am I doing wrong here in my calculations??
Here's what I have so far, please chime in if I've really got my
formulas screwed up:
1 lb potassium oxalate to 1400ml water to get a 35% solution
1 lb sodium acetate to 1400 ml water
1/2 lb ammonium citrate to 1400ml water
1 lb potassium citrate to 1400ml water
1 lb sodium citrate to 1400ml water
Hydrodchloric acid 1% solution for platinum, 0.5% for palladium
27ml of 37% to 1 liter of water
Phosphoric acid in a 2-4% dilution or 24-48 ml in 1000ml water
EDTA : use in a 2-3% solution, 1 Tablespoon per liter.
Citric acid: use in a 5-15% solution, or 4-12 T
TIA for helping me weed thru this, and then I can go back to gum testing
:)
Chris
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