From: Judy Seigel (email@example.com)
Date: 02/28/03-09:17:41 PM Z
On Fri, 28 Feb 2003 Ender100@aol.com wrote:
> This idea comes from Sam Wang, not from me. It's another view on the
> staining issue and it is very simple and makes a lot of sense to me—Thanks
> One issue of staining with gum, as I have read—correct me if I am wrong,
> don't correct me if I am Wang... anyway, as you add more dichromate solution,
> you add more water, which in turn dilutes the gum... the thicker gum is
> "supposed" to keep the pigment in emulsion and protect the paper from
> staining.... however, if you use powdered dichromate instead of the usual
> saturated solution, you are not diluting the gum.....
I have said before and will say and say again, I find the idea of mixing
powdered dichromate for each print about like, no, WORSE than mixing
aqua regia. It's powder, it sprinkles, it flips tiny pellets into the air.
It's KNOWN to be toxic, allergenic, sprinkly, poisonous, mean.
Not to mention that to be able to spread a gum emulsion you NEED it to
have a goodly amount of WATER. If it's all or mostly gum, it's just
sticky, tacky, and dries right way, you never can get a smooth coat.
Meanwhile, here is a MUCH simpler, safer solution. ALSO easier, quicker...
no weighing or spooning for each batch. Make up your Ammonium dichromate
solution full strength, or anyway 26%. Store in an 8 oz dropper bottle.
For most printing I dilute it 50% or so with distilled (also kept in 8 oz
dropper bottle.) When I want it stronger, I just DON'T dilute it. I have
never yet found a need for stronger dichromate than 26% two parts to gum
one part -- and with paint added to the mix, that is STILL quite thick.
Whoever might think that's thin enough to cause "staining" hasn't done it.
Mix it, coat it.... and you'll see.
In fact frankly, I think this discussion has got too many unsupported
assumptions to be meaningful -- it's all theory -- thinly spun theory.
Pleasant enough -- no baffling "findings" or lack of... but ....'nough
said. Oh one more thing... The glyoxal turned orange within minutes, at
most half an hour of the addition of alkali. The paper turned very
slightly brown weeks or more after hardening. Now tell me that was because
it was so dilute.... I'll tell you also that many times it didn't happen
-- never did show any browning or yellowing.
> Mark Nelson
> (Lurking & Listening Pays Off)
> In a message dated 2/28/03 11:28:42 AM, firstname.lastname@example.org writes:
> << Second, as far as pigment stain, is it possible (I'm still on this
> acid/alkaline wavelength so bear with me) that the more dichromate added to
> the sensitizer mixture, the more acid the mixture, and the more the paper
> stains because the acid "mordants" the color to the paper, as in dye
> mordanting or etching in mordancage? Like when you were a kid and dyed
> easter eggs and you used vinegar to "set" the dye? I came up with this idea
> as I was cyanotyping in my bathtub, and decided to try some straight
> vinegar, and it nicely fixed blue cyano solution ALL over my porcelain tub. >>
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