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  • Writer's pictureChiara

UV or not UV, that is the question

Sorting out my UV source proved to be the most challenging aspect of my cyanotype experiments. Obviously the sun is a big UV light source in the sky! However, Melbourne, where I live, is known for its variable weather and I have a number of other variables to contend with: a small overgrown garden, neighbourhood children whose soccer ball often comes over the fence and unpredictable work hours. Sources I consulted varied greatly in their opinion of the pros and cons of sun exposure. Reported results naturally also varied according to geography. This survey list exposure times from a few minutes to half a day. I opted to look for an artificial light source in the hope of having more control over my process.


I bought a halogen work light from the hardware store.

It was relatively inexpensive, compact and portable. Halogen light is known to have a significant UV component, so much so that the lamp glass has built in UV shielding. However I expected to still get some useful UV output. The major disadvantage I anticipated was the lamp's heat output.


I made a test strip and exposed in 30 second increments from 9 to 16 minutes. After developing, there was basically nothing left on the paper.


I repeated the test in 1 minute increments from 9 to 25 minutes. Still nothing.


Having already tested the frame set up, I was left wondering whether there was a problem with my substrate-chemistry combination or a problem with the UV source.


Taping a strip of coated paper to the inside of my studio window for a couple of hours while I got on with something else gave this result, which proved the integrity of my substrate and chemistry.

I went back to researching the halogen light and discovered some unwelcome facts. Whereas these lights are actually sold as exposure lights on various photographic screen-printing sites, they come with the following caveat: "* Be sure to remove the wire cage and glass from the light. The wire cage will cause shadows and the glass has a uv coating which will not allow it to burn the screen properly." I'm not keen on the idea of removing two safety mechanisms from a piece of equipment, so I set my halogen light aside.

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