The Dance of Interacting Variables

In gum printing, everything affects everything else, meaning there's a very complicated interrelationship between variables that produces the final image. This is good news and bad news. The good news is that gum is almost infinitely flexible and tolerant and that there's almost no combination of variables that won't print gum successfully, if the method is calibrated to accommodate the limitations and requirements of the materials and equipment. The bad news is there's no one way, or even one best way, to print gum and no one solution to any printing problem, so published or online instructions about gum printing can be contradictory and confusing.

But never fear; just keep in mind that there are many different ways to solve a problem in gum, and that there are few irreversible mistakes, and you'll do fine. For example, exposure and development operate in a complementary fashion so that you can often salvage a print that's improperly exposed by adjusting the development. Longer development (even a day or two) often salvages overexposed prints, and underexposed prints can often be salvaged, if the underexposure isn't too extreme, by developing them a shorter time and drying them quickly before they start to run.

By the same token, you can adjust variables to solve other problems: if you are using a fairly weak light source, you might want to use a more concentrated dichromate solution to speed up exposures; if you are using a very strong UV source, like the sun, you might want to use a more dilute dichromate solution to avoid overexposure, and so forth. The possibilities for adjusting variables to control the outcome in gum printing are almost endless.

Balancing variables is also very useful in making multiple prints, where you want the darker shadows printed with a heavier pigment mix to give a dark DMax, but exposed and developed in such a way as not to fill in the highlights and midtones, as explained elsewhere, for example.

Once you understand how the variables operate in relationship to each other, by adjusting variables in deliberate ways you can create absolutely any effect you want with gum.

The fastest way to reliably successful gum printing is to print gum and keep printing gum. Adjust one variable at a time, take notes. It's like riding a bike; once you get it, you've got it for life. Good luck!

Related pages:

Thoughts on exposure

Thoughts on DMax and tonality

Thoughts on contrast

Process Notes


Copyright Katharine Thayer, all rights reserved.