Yellow pigments and Gum problem(s)

Dear List

I use Yellow (Schmincke PY154) , Phthalo Blue (Sennelier PB15) and
Quinacridone Red (Sennelier PR122) pigments for tricolor gum printing.

Until recent I have been using the same PDN calibration for all three
pigments - that is same negative color and curve - based on the cyan
negative.

>From Chris I got the the inspiration and energy and decided to calibrate
each color separately - and it was during this work I noticed
a phenomena that I have seen before but not given much thoughts.

When I use the yellow pigment I don't get clear and discrete steps on the
21-step Stouffer , I cannot recognize the borders between the steps.

The density is fine and I get something like 7 steps on the Stouffer which I
find OK.

When I make a test with the Cyan and Magenta I see perfect steps.

Has anyone here on the list seen the same - what maybe even know the reason
and possible consequences?

Is this yellow pigment bad for doing details and fine lines?

regards

Roman Sokoler

http://www.alternativephotography.com/artists/roman_sokoler.html

----- Original Message -----
From: "davidhatton" <davidhatton@superonline.com>
To: <alt-photo-process-l@sask.usask.ca>
Sent: Wednesday, November 23, 2005 6:54 PM
Subject: Re: Gum problem(s)

> Christina,
>
> Would it be true to say then that you size BEFORE your cyanotype layer ?
>
> David H
>
>
>
Received on Wed Nov 23 16:58:35 2005