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

[Luciano Teghillo]

Carole,

Since I am also an engineer at heart I have made a little shaker by
recycling an old motor and some metal bars from the hardware store. So when
I start a session, I first stir the mix with a glass rod and then slip the
container in the shaker and let it go during the setup. But it is good to
know I am not the only one experiencing the separation.

The magenta is Winsor and Newton, Perylene Maroon, PR179
The blue is Maimeri Blu, Ultramarine Deep, PB29

BTW, this is one of the mixes suggested in Christina book (the yellow PY97 I
use is a viable alternative but not the one suggested, will see how it goes)

Luciano




-----Original Message-----
From: alt-photo-process-list-bounces at lists.altphotolist.org
[mailto:alt-photo-process-list-bounces at lists.altphotolist.org] On Behalf Of
gumprint at gmail.com
Sent: Wednesday, February 05, 2014 11:10 PM
To: The alternative photographic processes mailing list
Subject: [Alt-photo] Re: GUM: problematic yellow?

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
> _______________________________________________
> Alt-photo-process-list | altphotolist.org
>



--
*Carole *

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