After reading a “how to” in Printmaking: a complete guide to materials and processes (authored by Grabowski and Fick), I decided to make my own plates using their process as a guide.
The materials I used for my first experiment were:
4 x Acetate sheets (10 x 13 cm approx.)
Gel Medium (Derivan brand)
Tarlatan fabric (the stiff fabric used to wipe back intaglio plates)
Speedball Diazo liquid emulsion
To make up the plates I first prepared a different surface on each, to create a type of Aquatint layer. Pretty much a surface that would grab and hold the ink.
Plate 1 (below): Tarlitan fabric adhered to the plate with PVA glue. (Tricky as the glue beads on the plastic.)
Plate 2 (below): Gel medium brushed on, with brush strokes in every direction to create a textured surface.
Plate 3 (below): The surface was given a light sand with course grit paper and then covered with a thick layer of Gel medium, tarlitan fabric was pressed onto the surface and then pulled off to create a stippled effect.
Plate 4 (below): Gel medium was used to adhere a piece of tarlatan to the plate.
Once the gel medium / pva had dried, the fabric on plates 1 & 4 was trimmed neat to the edges of the
Using the Diazo liquid emulsion as directed, each plate was covered with a generous coat of emulsion and left to dry on a flat surface in a light proof cupboard. (The emulsion becomes light sensitive when dry.) Approximately 24 hours drying time is required.
To get an image onto the plate, you need to create a film positive. To do this you essentially create a design or drawing in positive (ie: black on white) and then copy it onto transparency film. I used black paper cut outs, glued onto white paper, which I then copied onto ezyscreen A4 artwork transparency film. It can be copied onto with an inkjet printer, or you can draw your design straight onto the transparency with a black marker. (However it cannot be used in a photocopier.) The tone on the transparency must be opaque enough to block out the light when the plate is exposed. Below is a photo of the paper design
As the Diazo liquid emulsion is primarily used for photo positives on silkscreens, I had to experiment with the exposure times. I used an exposure unit with a UV lamp, and a plate glass base that the film positive and sensitised plate could be placed under, so that the film had even contact with the plate.
Again I followed the instructions that come with the emulsion kit regarding height of lamp and processing of the plate. The times I used were: Plate 1 :exposed for 2 minutes, Plate 2 and 4 : exposed for 1.5 minutes and Plate 3 : exposed for 3 minutes.
Wash out was in a tub of warm water, and I used a soft bristle brush to gently assist the emulsion in coming away from the plate. A fair bit of rubbing and swishing around in the water was undertaken!
With this type of emulsion, less time during exposure renders a stronger “white” while a longer exposure begins to break down the white areas, and therefore reveals the aquatint surface below. Where the light hits the emulsion, (ie the clear part of the transparency film, the emulsion will harden and stay on the plate. Where the light is blocked from the plate the emulsion washes off, thereby exposing the aquatint surface
and ultimately printing black.)
Once the plates were washed out I put them under the light again to harden off the emulsion.
The next step I undertook was to shellac the plates as with a collograph. This was to protect the aquatint surface and the emulsion from the rubbing back involved when the plate is inked.
Graphics Oil based bone black ink was used to print the sample plates onto Somerset water colour
paper, in an intaglio manner.
The reason I used Acetate plate to build this collograph on was the simple fact that the emulsion had to be processed in warm water, and I thought a regular cardboard plate (even if it was shellaced on both sides)
wouldn’t have stood up to that part of the process.
Before the emulsion hardens off completely it would be possible to work into it with a drypoint stylus, to add a fine line alement to the plate.
It would probably be possible to print a plate made in this way in relief, my assumption is that the emulsion would have to be very even and probably nice a thick.
My next experiment is to use silkscreen fabric in place of the tarlatan, to create a finer aquatint surface.