Photographic Sceen Printing

This is how screen printing works:
Imagine a screen made with fine see-through fabric stretched over very tightly.
Take a sheet of paper the size of the screen with one letter, say a "T" cut out.
Attach the sheet to the screen,.
Lay the screen face down on paper or fabric.
Squeeze paint onto the edge of the screen.
Using a squeeqee pull the paint through the screen, in exactly the way you'd clean a window.
When you pick up the screen (which hinged to the table), there will be a T.
(Because the rest of the ink was blocked by the paper.)

Okay: These screens were masked photographically.
1. Here is a screen before the image is added, with the artwork which has been laser printed onto tracing paper or acetate. The image has to be a very dense black so that light can't penetrate it. The screen is 50cm x 40cm.

 2. In the darkroom, a light sensitive liquid, Dirasol, is used to coat the screen. The screen is then dried and kept in the dark. The Dirasol is purple.

3. Still in the darkroom, the tracing paper image (Fibonacci) - is placed on a huge lightbox.
(The colour is weird because it a darkroom lighting!).
Fibonacci Squence had to be done in 6 separate screenings.
I could fit Fibonacci on one screen broken up into Fib - on- acci, then I printed one part at a time.

4. The now-dry screen, coated with Dirasol is placed face down on top of the image.
This is a very sophisticated lightbox which has a suction mechanism that suctions the lid tightly onto the image so that its pressed very firmly against the screen.
The lightbox is switched on and a timer set - e.g. 1 minute and the image is exposed.
The light hardens the Dirasol except where it can't penetrate i.e. through the black letters of Fibonacci.

5. Quickly wet both sides of the screen and gently wash the Dirasol out where the letters are.
Now the image is ready. This is a photo of my technical assistant, Heather Power,  washing the screen. I used the Oxford Printemaker's workshop and had a technical assistant - which was just as well as this was a two-man-job!

6. I had to mask off  the on - acci, with parcel tape and just do the "Fib" first.
This photo is of the screen being cleaned after the first screening of "Fib" on three pieces of silk
Tomorrow I'll show some details of the finished banners!

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