From: Kerik (Kerik@kerik.com)
Date: 03/03/03-03:20:49 PM Z
Christina,
> 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?
To my knowledge, most people don't do this. "Most people" use equal
amounts. In reality, if you made a print with 44/46 and a print with 44/44
you wouldn't be able to tell the difference. That amount of difference is
insignificant.
> 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?
I think there is a bit of old wives' tale going on with this. I've read
and heard the same thing several times. I've been teaching platinum
printing for 6+ years now. Beginners often have a little difficulty
getting the print submerged completely on their first try. I've never seen
a demarcation line remain on a finished print.
> 3. I am getting so screwed up by the different proportions of chemicals
> in the developers and clears. Is it really that variably OK?
Yes, it is. I routinely use Kodak Hypoclear at regular working strength.
Or, 1 tbsp of EDTA and 1 tbsp sodium sulfite per liter. I rarely clear
with acids unless a paper is stubborn to clear. And then I use a 4% citric
acid bath. I never use HCl or phosphoric any more.
> 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?
I'm no chemist, but yes.
> So why does one book call that an 8% solution?
Either the author made a math boo-boo or it's a typo.
> 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?
0.5 oz (of a 100% solution) in 32 oz of water is ~1.6%. Since HCl usually
comes as 37% stock, then 0.5 oz of 37% solution in 32 oz of water is ~0.6%.
None of the clearing bath formulas are that critical. Stick with Kodak HCA.
It works great with most papers.
> 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
I only use potassium oxalate. I use it at a 30% solution. Again, I don't
think you'd see any difference in a print developed in 30% PO vs. 35% PO.
Don't let the numbers overwhelm you. Platinum printing is very easy,
although some people seem to like to make it way more complex than it needs
to be.
Hope that helps.
Kerik Kouklis
Platinum AND Gum printer
www.kerik.com
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