Discovering the Magic of Photochromic Pigment: Creating Temporary Art

I've been sharing a series of experiments with photochromic pigment online recently. Check out this quick "trailer" to see some of my favorite experiments:

Thank you to my friends at the Tinkering Studio for this fantastic blog post & gallery. We experimented with photochromic pigment during my residency in March 2023.

Many have asked about what materials I'm using and how the process works. And since I shared these initial experiments, a small crew of creative friends have been sharing their own experiments with these materials. This blog post is a running record of our shared explorations, and includes tips for getting started if you want to experiment with these ideas. subscribe to my very infrequent newsletter if you want to be updated about this sort of thing.

The big idea: I'm using a UV led light to "paint" onto paper and other objects that are covered with a photochromic pigment mixture. This is not a permanent process. The image lasts for a minute or so before fading away. (this is kind of how transitional glasses lenses or "invisible ink" work they change color temporarily when exposed to UV light like the sun)

Here are some suggested steps to follow if you want to try this out:

Order some photochromic pigment. I used this one: https://atlantachemical.com/sun/wv_pp_sun.html? .You can see that they have other color options, like a pigment that goes from pink to blue. I picked the white to violet one because I wanted the pigment to blend in with the white paper when it wasn't activated. I think I ordered the 20g container but I only needed a tiny amount to cover my paper.
Mix the pigment with something like paint, glue, or mod podge and apply it to the surface of your choice. You might need to do some experimenting here. At first, I used white Elmer's glue (about 1/4 cup) and mixed it with about 1/4 tsp of pigment powder, this was more than enough to coat a few sheets of paper with a lot leftover. I used glue because I thought that it might dry clear, but it didn't because the pigment itself has an opaque white color. Now- I highly recommend trying Mod Podge (thanks Cate!). Mod Podge was much easier to paint with. You can use anything from foam paint brushes to ink rollers to paint your pigment + mod podge mix. Keri tried mixing the pigment with white tempura paint and that worked as well (see some of her images below). Note: I tried mixing this pigment with screenprinting ink and it lost its color-changing properties. I suggest experimenting with small quantities of paint/pigment first before mixing up a big batch!
Let your painted surface dry
In the meantime, find a UV LED light or UV pen. I had some small UV LEDs handy but I found that when they were powered by a small coin cell battery, they weren't quite bright enough to make a dramatic color change. Instead, I ordered a pen like this. I also tried these smaller pens, they're great for "drawing" with UV light and they're also a little cheaper if you're ordering materials for a class. The only downside is that you can't replace the battery once it runs out so they are single use. You can also use sunlight! I did some experiments where I tried to "catch" patterns of light and shadow coming in through my windows.
Now you're ready to experiment. I'll share some of the prompts I, and others tried out below. I also think this is a good way to introduce the idea of how processes like photo emulsion or cyanotype photography work.

Prompts:

Experiment with found objects to see what kinds of patterns and shapes they make.

Try creating new shapes by "exposing" the materials repeatedly.

Check out the ways that Cate and Keri experimented with found materials. I loved the way that Cate connected these materials to "making faces" and the ways that Keri's students created beautiful temporary art collages.

Here's another prompt to consider from Cate: Make a mixed media college with materials like torn paper and real objects.

Create customized "stamps" or "stencils" by drawing onto clear materials, like transparency paper.

I used a china marker to draw on the transparency because they are waxy and opaque. You can place the transparency on top of images or patterns to trace them.

Print your own "negatives".

I printed images I found in the Smithsonian's open collection. I had to do a little bit of photo editing to make them work the way I wanted them to (so that they print a positive version of the image on my paper). I converted the image to black and white, inverted the colors, and played with increasing the contrast a little bit. Then, I printed the images onto my inkjet-friendly transparency paper.

Tinkering with transparencies at the AIMS center in Fresno

"Catch" patterns made by the sun.

Like this pattern made by the light coming in through my blinds

You could also consider taking your photochromic surface outside and create collages in collaboration with the sun. Cate notes that you've got to work quick outside!

Take a "shadow walk"

Take your photochromic surface and a UV flashlight with you and explore your surroundings to create interesting shadows.

Collecting a shadow from an exhibit component at the Exploratorium

Make it Permanent

You can use the same materials, prompts, and processes that I describe here to create permanent versions of your art. All you need is some "sun print" paper, or cyanotype "sensitizer" (a solution that you mix and paint onto paper or fabric, I like this brand). You'll have to experiment to figure out how long to expose your art to sunlight or UV light. Cyanotypes take a few minutes to develop. If you don't expose them to the light for long enough, or if your light source is too weak you'll have a very faint image. I've had good luck putting my artwork in the sun for ~15 or 20 minutes or using the kind of UV lights that screenprinters use like this one, but you can likely find cheaper options.

See how Keri and Sebastian made their artwork permanent:

Sebastian's permanent art piece, using a bigger UV light and watercolor paper coated with cyanotype sensitizer.

I loved the experimentation here! You can create beautiful effects by moving your light sources around as you create your permanent art piece.

Odds & Ends:

Don't want to order pigment? Try Elmer's color changing glue!
UV-sensitive beads exist! And can be fun to use in classroom science lessons

What's next:

I'm working on a small kit and playful zine that guide you through experimenting with these materials and processes. All of it will be open source, but I hope to have some pre-printed and packaged for those of you who want to just pick something up and get started