Tuesday, February 2, 2010

cloud chamber

Yesterday, I had a screenprinting class at Open Studio. I've done a lot of screenprinting (also known as silk-screening, but these days, the screens needn't be silk) in the past, but always with a paper stencil (or, a fern leaf). I had never previously tried using a photoemulsion. This lets you make a stencil using photo-chemistry - you basically "burn" a photographic image right onto the screen. It can be of basically anything, but I choose something that would be particularly hard to represent with other printmaking techniques (because of the fine lines and the fluffly texture). I call this two-colour screenprint "Cloud Chamber".

cloud chamber

A Wilson cloud chamber is basically a tank of condensed, supercooled water (or alcohol) vapour. It is used to detect high energy particles - ionizing radiation. The radiation, say from cosmic rays, or radioactivity, or particle accelerators and so forth, leave their distinctive trails in the "clouds". Because of conservation laws (conservation of angular momentum, and conservation of charge, in particular) you get these wonderful spiralling trails. If you look carefully, there's a whole lot of symmetries in the image. In fact, if you look really carefully and measure angles, it's possible to get the mass to charge ratio of the particle in question. It's really a magic piece of 20th century science instrumentation.

ionization tracksCloud Chamber detail

The image is made in two parts. First I found a nice photograph of clouds and I manipulated it in Corel Draw. I likewise came prepared with an image of ionization tracks from a cloud chamber found online. I "burned" these onto the photoemulsion-coated screen. First I printed the cloud-image in periwinkle-sky blue on several sheets of paper. We only had three hours, so the idea was to see what could be acheived, more than to produce a multi-coloured precision print. I did manage to also print the ionization tracks in golden-yellow on top of the sky. I was thinking of the sun, the source of most of our cosmic radiation.

My registration reflects the rushed nature of a single three-hour class; it isn't always what was intended, but I thought ahead a planned this image to be flexible. In fact, this is "Cloud Chamber II", with the ionization tracks printed 180 degrees out of phase:

Cloud chamber II

I like that too. :)

Our teacher was Genevieve, whom , I think, knows. There were five in the class and in typical Toronto fashion they were from Toronto (me), Thailand, Trinidad, Pakistan and undisclosed (sounded like Southern Ontario to me). It was a good little group, which is great because we share resources. My partner's English was a bit limited, but she's clearly extremely bright, exudes competence, and is really considerate. We were using the screen as a coordinated team almost without using words, which was pretty impressive to me.

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