Photograms are images made on photosensitive paper called Sunprint. The paper is essentially blueprint paper or some form of cyanotype. The chemistry is potassium ferricyanide and iron ammonium citrate in solution. More about this at the end of the post. The image is made by placing an opaque object on the paper and exposing it to the sun. The image is then washed to remove the unreacted chemicals for semi-permanence. But what can you do if you don't have the chemicals or the Sunprint paper? Make your own using construction paper! Most dollar stores have variety packs of construction paper in many colors. This paper is cheap because of the low quality of pulp used, and the dyes that are called fugitive. They fade easily in the sun. So, I took samples of all of the colors in the pack and placed opaque quarters on the samples and put them is the sun for six hours. I wanted to use reflective metal to minimize the effect of heat on the dye. See before and after photos below:
The sample with the most contrast seemed to be the red, so I used a fern under a piece of glass to make the image in photo one at the top of the post. But this has other potential as well. How about testing several types of clear plastic the see if they have UV absorbers? Or different colored plastic? Theoretically, yellow or amber should block blue and UV while blue will pass all blue and UV. What about putting a thin film of sunscreen with different SPF values. Well, you get the idea. For the next post I will show how to make blueprint paper with the above mentioned chemicals. Pretty cool and the image only requires about 20 minutes of sunlight. Stay really still and smile!
The author has an eclectic background in chemistry, electronics, writing, mental health, and community action...Ken