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

[Luciano Teghillo]

Before I start printing I need to find the time that will give me maximum
black on the step wedge. That mean that the clear part of the wedge (where
Stouffer is written) and step #2 need to turn the same "shade". With the
step wedge you will also see how many steps your mix, printing time, and
development will provide.

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
Kurt Nagy
Sent: Wednesday, February 05, 2014 7:54 PM
To: alt-photo-process-list at lists.altphotolist.org
Cc: <alt-photo-process-list at lists.altphotolist.org>
Subject: [Alt-photo] Re: GUM: problematic yellow?

This may be a dumb question but what are you looking for result wise with
the step wedge, I've never used one before.

Are you aiming for exactly halfway down the wedge??

> On Feb 5, 2014, at 12:24 PM, "Luciano Teghillo"
<luciano at lucianoteghillo.com> wrote:
> 
> 
> Hi Diana,
> 
> Yes the paper works great. I cannot thank you enough for the suggestion!
> I will need to get my color wheel out and see if I can find another 
> yellow in the Maimeri pigments that works with my combination of 
> colors (which I still need to prove when layered together) or maybe try a
different gum.
> 
> I hope I can solve this one quickly, test my inkjet negatives and get 
> on with some prints...step wedges are boring :-)
> 
> 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 Diana Bloomfield
> Sent: Wednesday, February 05, 2014 6:55 PM
> To: alt-photo-process-list at lists.altphotolist.org
> Subject: [Alt-photo] Re: GUM: problematic yellow?
> 
> Hi Luciano,
> 
> I'm so glad you manage to get some of the Fabriano and work with it, 
> and that you like it.  It is pretty amazing paper, isn't it?
> 
> That's interesting about the yellow.  I know people always say they 
> often have trouble with the blue pigment, but I never hear anyone talk 
> about problems with yellow.  But I never had a problem with blue-- not 
> sure why-- but I always always seemed to have issues with yellow, 
> until someone (on this list, I think) suggested Quinacridone Gold for 
> yellow.  I can't remember now which yellows I used that gave me so 
> much staining-- they all seemed to as I remember-- but ever since I 
> switched over to Quinacridone Gold (Daniel Smith or M. Graham), I haven't
had a problem.
> I also don't make stock solutions, so can't help you there.  But my
> (unscientific) thought is that it's the pigment itself.  If you can 
> find the Quinacridone Gold somewhere, it would work for you.  I also 
> like it as a yellow layer-- as it's not so much an 
> in-your-face-yellow-- as it is a rich gold.
> 
> Diana
> 
> 
> 
> 
>> On Feb 5, 2014, at 12:27 PM, Luciano Teghillo 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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