The Other Colors

{Gum Arabic + Pigment (Watercolor or Gouache)}+ Potassium Dichromate = Gum Print

It only seems fitting to follow up the blog about blue with a blog about the other colors that I use during the gum printing process. The cyanotype (blue) layer is more about the color than the actual process of making the color because I am using two chemicals at a 1:1 ratio and it is very straightforward. The gum pigments, on the other hand, involve numerous color and process choices.


I found that I needed to pre-make small batches of gum pigments (gum+pigment) that are ready to use at the time of coating. The pigment and the gum can be stored in mixture until you are ready to add the potassium dichromate (light sensitive chemical) at the time of coating. The pre-prepared mixtures really move the coating process along, especially because the quite cheap scale I purchased to weigh my pigments does not always behave (causing cussing and time).


All of the small batch guides I researched used the somewhat inaccurate method of measuring a ‘worm’ or ‘pea’ of pigment. I wanted my pigments to be easily repeatable with consistent results so that wasn’t the process for me. The more accurate methods that I found were for large batches and it would take dreaded math for me to scale the measurements down to my student budget proportions. Most of these (if followed) would have caused my 500 ml of gum arabic to be used up in the creation of bulk pigments, which wouldn’t leave much to play around and experiment with.


So, after much research of other’s processes and after watching Brian Taylor (his work is featured in an earlier blog) step through his process on a video, I decided to try his pigment to gum ratio as my base mix ratio. Taylor uses gouache as his pigment of choice because the opaqueness of the gouache gives his images a sort of heavy richness. I have also been experimenting with gouaches, mostly because I already had them lying around. He uses 1 gram of pigment to 10 ml of gum arabic for his pigment solution. I have been halving his quantities to make the perfect (for me) small batches (0.5 g pigment : 5 ml gum arabic).


0.5 g Winsor New Primary Red Gouache + 5ml of Gum Arabic


I have found that I am getting consistent exposures and prints using this as my base quantity. I can then further dilute with more gum at the time of coating if I think the pigment is too strong. If further dilution is needed I use a pipette and count the drops of gum solution + the drops of additional (non-pigmented) gum, and then make sure I add the same amount of potassium dichromate to give a final 1:1 solution. I do not particularly like counting drops from a pipette, but it gives me a fairly accurate measurement to go by and I can make really small quantities. Some day I will get a 1 to 5 ml graduated cylinder and then perhaps I will not have to count drops, but until it’s the drops for me.


I keep notes for each print that I process so that I know if I further diluted a pigment solution or if I perhaps mix two colors. This process for making my pigments has given me a really consistent base to work from enabling further experimentation with my color layering.





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