[Alt-photo] Re: GUM: problematic yellow?

[gumprint at gmail.com]

Luciano,

I, too, had a lot of trouble with various yellows until I switched to Quin
Gold. It's warmer than a cadmium yellow, which would go well with your
magenta.

As for gum/pigment separation, it is normal. I keep mine in 15 and 30 ml
glass jars that are tall and thin like tubes. I slip them into my pocket
when I begin a printing session and give it a roll on the counter or
between my hands every few minutes. This brings the mixture back into
solution without foam or pigment settling on the bottom. I draw the
solution out with a non-needle syringe.

Would you share the brand and color name of your magenta and your blue?
They are lovely.

Best,

Carole


On Wed, Feb 5, 2014 at 12:27 PM, Luciano Teghillo <
luciano at lucianoteghillo.com> wrote:

> After Diana suggestion (thanks again) I was able to source some Fabriano
> Artistico soft-press and I was able to print some exposure tests. The paper
> is great! I am not getting any stains, and finally I am printing something,
> even if they are only step wedges without having to pre-shrink, size, etc.
> etc.... The final test will come as soon as I can print more layers....
>
> So far no problem with blue
> (http://www.lucianoteghillo.com/images/scan-blue.jpg) and red
> (http://www.lucianoteghillo.com/images/scan-magenta.jpg) but yellow it's
> not
> printing correctly, at least that's my impression.
>
> After the first test
> (http://www.lucianoteghillo.com/images/scan-yellow1.jpg) with the usual
> exposure times used for blue and magenta (from 1 minute to 3.30 minutes in
> 30 seconds intervals), it looked like I was not reaching maximum "black"
> but
> also the steps didn't look as defined as with the other colors. So I
> decided
> to print one more test with exposures of 16, 32 and 48 minutes
> (http://www.lucianoteghillo.com/images/scan-yellow2.jpg). I think this
> second test is event worst than the first.
>
> Now everything is the same: same gum, same potassium dichromate, same
> process. I mix a stock solution with 15ml tube and 45ml of gum, which I
> then
> further dilute as needed. In the case of yellow, I mix 1ml of stock
> solution
> with 1ml of gum and 2ml of 12% potassium dichromate.
>
> The watercolor used for yellow is Maimeri Blue, Primary Yellow, PY97
> (Arylide yellow, also known as Monoazo yellow).
>
> This might be important or not, but I noticed some separation between gum
> and pigment in the stock solution bottle. If I let the bottle rest for a
> day, I can see a ring the color of gum 1/4" thick on top, something I did
> not notice with the other colors.
>
> Do you have any advice? I do not have other yellow tubes from other
> pigments/brands but I could look for it. It just seems strange that I
> cannot
> print this color!!!
>
> Thanks,
> Luciano
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>



-- 
*Carole *

*"What good is knowledge if it is not shared?" *