Re: Gum woes revisited

From: Katharine Thayer ^lt;[email protected]>
Date: 05/20/05-04:24:13 AM Z
Message-id: <428DBAB5.4595@pacifier.com>

Hi Scott,

A couple of thoughts:

In your earlier post you listed a whole lot of paints and asked for
comments on the pigments. I don't know if you got any comments other
than my own about the pigments, since I've been too sick to read that
whole thread, and I only commented briefly on the two lines of paint
that I personally felt to be of inferior quality and permanence, the
designer gouaches and the Grumbacher.

Now, since you asked earlier, I'll comment on the specific pigments you
mention here from Winsor & Newton.

Winsor & Newton's "lemon yellow" doesn't belong to the same pigment
families as most paints called "lemon yellow" which are most often a
hansa (arylide) yellow, like PY3, or a cadmium yellow (PY35 or more
rarely PY37). The W&N "lemon yellow" is nickel titanate (PY53) which is
a rather dull pale pastel, somewhat opaque yellow, it looks in the
swatches like a way watered down yellow ochre. (I haven't used it
myself; I'm just looking at swatches from various manufacturers and at
the description at handprint.com) Just from the swatches and the
description, PY53 wouldn't be my first choice for tricolor work
(although it should be admitted that my own personal first choice is
also a sort of offbeat choice, so I'm not looking down my nose at an
unusual choice). The reason I wouldn't choose the nickel titanate is
because it's such a wimpy, dull yellow; I'd personally want something
more intense and bright to hold its own with the other colors in a
tricolor.

The cadmium red is also somewhat opaque. I prefer transparent pigments,
myself, for tricolor work, but at the dilution you're using them here,
these opaque pigments are probably at least semitransparent. I'd be
interested to see the prints, is there any way you can post them?

Several months ago, because of a discussion that was going on here, I
was thinking a lot about pigments for tricolor work. I'd have to go back
and find that thread to be reminded of what I was thinking at the time
about it, but one of the things I remember speculating about was that in
order for a particular combination of pigments to work, the individual
pigments probably need not only to have compatible reflectance curves,
but also to be equidistant on the color wheel. Which brings me to the
thought that for a good color balance you'd probably need a different
yellow and magenta to go with the new cyanotype (which to my eye is more
like a pthalo) than the classic cyanotype (which to my eye is more like
an ultramarine). Just something more to add to the mix,
Katharine Thayer

Scott Wainer wrote:
>
> Hello all,
>  
> Just an update on my journey into gumland. After changing almost
> everything I was doing I began to taste success, except for a slight
> problem of not being able to get a smooth first coat (cyan printed
> using ultramarine). After a little head scratching and reading Sam
> Wang's article on 3 color gums (unblinkingeye.com), I tried using
> cyanotype as a first coat. It was a mess, even with a change of paper
> (to Fabriano Uno) I still had a hard time getting the first coat of
> gum smooth (this time with lemon yellow). More head scratching and I
> decided to give the paper a second coat of sizing and to dilute my
> pigment/gum solution even more. Everthing worked perfectly. Here's
> what I came up with:
>  
> Paper:
>      Fabriano Uno
>      preshrink by soaking for 1 hour at 140F
>           allow to dry before sizing
>      2 brush applications of 3% gelatin size
>           30gm gelatin + 3gm Chrome Alum per liter
>  
> Cyan base:
>      New Cyanotype (1.5ml for a 5x7 image)
>           add 2 drops 5% Tween20 per 10 drops of sensitizer
>           add 2 drops 40% citric acid per 10 drops of sensitizer
>  
> Pigment/Gum:
>      pigments - Winsor & Newton artist grade watercolor
>           Lemon Yellow for yellow separation
>           Cadmium Red for magenta separation
>      gum - Daler-Rowney (light amber)
>      ratio - 1gm pigment to 20ml gum
>  
> Process:
>      1. print image in cyanotype using digital negative with cyanotype
>          curve applied - printed and processed as a normal cyanotype
>          approximately 5 minute exposure - 10 minute development -
>          peroxide bath - 10 minute wash - blowdry on hot 10 minutes
>  
>      2. yellow separation -
>          apply pigment/dichromate at 1+1 and allow to dry 1 hour -
>          sensitizer went down very smooth - no blending required -
>          expose 2 minutes and develop for 1 hour in 3 still baths -
>          dry overnight
>  
>      3. magenta separation -
>          apply pigment/dichromate at 1+1 and allow to dry 1 hour -
>          sensitizer went down very smooth - no blending required -
>          expose 2 minutes and develop for 1 hour in 3 still baths -
>          dry overnight
>  
> Changing to a more dilute pigment/gum ratio and adding the second coat
> of size did wonders - no more worries. While the colors (as I see
> them) are different from the original I like what I am getting and
> will try other colors in the future.
>  
> Thanks to everyone for their help, Scott
>  
> swphoto@verizon.net
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Received on Fri May 20 16:20:00 2005

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