For my final project I would like to explore the crossroads of the potassium bichromate gum printing process and thermochromatic imaging. The question I would like to pose: How can thermochromatic paint be utilized in photography, both aesthetically and conceptually?
Gum bichromate is a difficult but rewarding photographic process. The first instructional was produced by Van Hubl in 1898, but the process existed since the 1850’s when Alphonse Louis Poitevin made the first color images (Enfield, 206). The process operates under the same principles employed by modern screen printers, and utilizes the relationship between cyan, magenta, yellow and black to build an image with a full color spectrum.
It is not, however, necessary to print in full color, and the process may be chosen for its ability to print images with a wide spectrum of interesting results.
Contemporary gum printers are often adored for their ability to create majestic images from black and white negatives, and the process has a unique look that some might describe as vintage.
Here is an instructable that goes over thermochromatic imaging in a screen printing style
Here is an instructable that goes over the basics of gum bichromate.
But there are several important things that I would like to add.
SIZING YOUR PAPER
Sizing is extremely important and referenced in this instructable, but not fully elaborated on. Sizing is the process of filling the gaps in your paper’s construction with organic material. Watercolor paper is absorbent and filled with with micro holes. Because of this, the process of wetting and drying the paper will cause the paper to shrink. This can become problematic if you intend to expose and wash your image multiple times. This is a contact negative process, which means the negative must touch the paper directly, and therefore if your paper shrinks than your image in process will shrink, and the resulting image will look as though it is out of focus.
You can avoid this by doing several things. Sizing paper with gelatin has been the most effective for me, but before that you should dip all of your paper in boiling hot water and dry using a blow dryer. Think of it like putting a wool sweater in the dryer. You want to shock the paper quickly into submission, and there’s good reason for this. Washing the paper repeatedly will slowly deteriorate the fibers, so I prefer not to size or expose an innumerable number of times.
I’v found that sizing with gelatin is the easiest but you may also size the paper with gum Arabic itself. Doing an exposure of gum Arabic with potassium bichromate will result in a surface that should not stain. This may however cause the paper to orange a bit, but if you’re using a full color process you may not notice these results.
Here is a link that shows you how to size your paper with albumen–a mixture made with egg whites and photo grade citric acid–but you may follow these steps when sizing your paper with gelatin.
TESTING IT
What I have found so far is the following.
Potassium bichromate process mixed with thermocromatic paint appears to work. The pigment is a bit starchy. It does not react well to direct manipulation with a paint brush in the development process, but it is firm. Mixing the pigment into a water-based solution before applying it to the gum Arabic and bichromate is also a volatile process. It’s important not to add too much water. The pigment doesn’t seem to hold as well when excessive water is added, which makes sense as this could dilute the gum Arabic. But not adding water to the pigment creates equally problematic results—the mixture becomes to think and the highlights do not properly expose.
The biggest challenge thus far has been in finding the right proportion of pigment to mixture, and I will attempt to find a method for effectively measuring this. However, an exact solution may not be possible as gum printing is a process reliant on many inconsistent variables. The type of light source you are using, the temperature of the room, the temperature of your wash and the sizing of your paper may all vary to slight degrees, and these changes can alter the process. Gum printing is a process for those who can embrace mistakes and thrive in inconsistency. However, that does not mean that mastering the basics is impossible, and working with this material provides possibilities.
STRATEGIES MOVING FORWARD:
So what can we do with this? What does it mean for an image to disappear?
Photography is often considered a static medium, in that the image is constant and the result unchanging—at least in form. With advent of the filmic image we have come to understand that pictures can move, but expressing time in still imagery has also become a photographic approach all its own.
Thermochromatic imaging may allow us to manipulate the components of images, or entire images themselves. The act of disappearing has many implications. That an image or piece of an image may be manipulated provides a series of possibilities, and aritisically I am looking to examine the following questions:
– What does appearance and the act of disappearing mean? How is this already explored in contemporary and classical photography?
– How can thermochromatic paint and photography mix? How would one interact with a piece that relies on a relationship of heat contact?
– Should this process be used to conceal or reveal? If an element of the image relies on thermochromatic relationships, than that element will either appear or disappear depending on how we use it. How can these possibilities be used to meet either narrative means? Which is more effective?
– How can the use of thermochromatic material speak to the history of gum printing as a medium? Are there other, more effective ways of producing these images? What are the advantages and disadvantages of this process?
My research so far has turned up no results of thermochromatic pigments in gum bichromate and it so far appears to be an uncharted territory. It has, however, been used in screen printing which relies on many of the same principles to produce images. So the goal of my project will be to find a way to highlight gum bichromate as a process.
One unique element that has already been discovered in my investigation is that potassium bichromate is not an entirely invisible process. Printing leaves visible layers of the image regardless of pigment. These layers are caused by a buildup of gum Arabic, and the result is a faint outline of the negative.
See the results here
THE PROJECT
I decided to make Balding Britney, an image that is an amalgamation of a cyanotype and gum bichromate.
In order to do this I made two negatives in photoshop. One out of the iconic bald Britney photograph, another of a wig. Here is a ling on how to make negatives:
http://www.freestylephoto.biz/alternative-process/making-digital-negatives
And here is how to make a transfer using packing tape (and thus a negative):
http://www.wikihow.com/Create-a-Photo-Transfer-With-Packaging-Tape
RESULTS
Well that was a shit show.
So let me say a few things about this whole process that might help you avoid the mistakes I made.
First of all, relying on Parisian winter sunlight is probably the dumbest thing you can do. If you do that you’re an idiot. So don’t. I did. Because I’m an idiot.
Now let me tell you what you can do:
Some art schools have UV boxes and some don’t. But they’re useful. They can be used for anything from making art to growing vegetables for an oddly conceived culinary program. A smattering of seconds on youtube and I’ve already found a cheap example:
WHY A UV LIGHT BOX!?!
Well there’s a lot of reasons actually. From photography to screen printing to painting to growing vegetables, there are a wide variety of arts that can utilize UV light for interesting and inexpensive results. And a UV box, unlike like sun, can provide measurable, constant results.
This is very important in screen and gum printing, because measurable results mean the ability to troubleshoot problems and actively replicate solutions in an efficient, seamless, and time effective manner.
Sunlight can also be fun, but is not frequently used in the practical, professional world.
Anyway, let me explain to you why my image is a mess.
because it was not possible to expose Balding Britney to a strong beam of constant sunlight, the paint and the gum arabic in the mixture did not meld. Gum printing, as a chemistry, requires this heavy interaction.
My solution was to paint the hair onto Balding Britney.
