Gum woes revisited

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
Received on Thu May 19 19:01:19 2005