First Test

Yesterday I decided to spend a chunk of time and learn how the polymergravure plates work. This material is Toyobo Printight KM73 and it is a photosensitive layer of polymer bonded to a thin aluminum plate that is very flexible.

I have a 21-step Stouffer test wedge and used it for my tests. I cut on a large old paper-cutter (the guillotine kind...) 3 seperate 1x8 strips.

I'm using the Nu-Arc plateburner in the USU lab. It measures units of light rather than seconds of minutes. The 'Joule' is a standard that is used to measure output and intensity of light. One joule = ???? I don't know actually, it's just a way to measure and quantify light. Here's how the tests broke down:

Test #1 - 100 Joules on step wedge, 100 Joules on stochastic screen

The method used is as follows:

a. place plate face-up
b. place step-wedge emulsion side down
c. sandwich with pressure under glass
d. expose for (x) Joules of light
e. remove step-wege
f. place stochastic screen emulsion side down on top of plate
g. sandwich with pressure under glass
h. expose for an equal amount as was done in step d
i. remove plate and process

Here is an image of the plate-burner with my plate sandwiched in my home-made contact printing frame.



After you have exposed the plate, you need to develop it in running tap water that is cool to the touch. Boxcar Press has a very good datasheet on the exact way to process the KM73 plate. You can download it from their site HERE.

One thing it DOESN'T mention is that you have to peel and remove a thin layer of protective film that is clear and kind of hard to see. I saw it and thought it was the actual polymer itself and was afraid of removing it, so I didn't.

I developed my first test strip with the protective plastic still on it. No image developed because no water was reaching the polymer. DOH! While it was developing under the running water, I thought I needed to make my exposure time longer so that I would get a good exposure on the plate. So, I started my next exposure while test #1 was still developing.

Here's how I did test #2.

500 Joules on step wedge, 500 Joules on stochastic screen

While the exposure for the screen was happening, I discovered that I needed to remove the film. A quick call to Boxcar and a chat with Nancy (?) and I realized I'd made a significant blunder.

I got back into the studio from lunch and removed the plastic film, and developed test #1. I did get a faint image that took on more relief as the plate dried and cured.

Since test #2 had already been exposed I decided to go ahead and process it also. I removed the film and processed it, getting slightly more relief on the plate.

If a little more exposure is good, then a lot more exposure would be better right? I cranked up the exposure unit to 999 Joules (it can't go any higher) and exposed the plate for test #3.

999 Joules on step wedge, 999 Joules on stochastic screen

I processed it and the relief is quite deep. Deep enough that I felt good about showing it around. Several who saw it thought it would work well to run through the press as a test, so I thought I would.

I got some BFK Rives and tore it down into small strips. I soaked them for about 20 minutes while I prepared the rest of the stuff I'd need.



Cole and one of the undergrad students (whose name ex-capes me right now) helped remind me how to prepare a plate and run the press. I did some printmaking as an undergrad, but that was in '94 and I'd forgotten everything I thought I'd learned. Good thing that there are friends around to hold my hand and help me along.

I got the plate inked up and ran a test.



I was pretty excited that it even worked just a little. I can see the step wedge and gradations but there are some problems.

I am seeing an uneven wave in the dark areas of the print. As I have inspected it I am deciding that it is the result of a wave in the actual plate. The plate is made out of very thin aluminum (I think...it might be stainless...) and as I cut it I can see that there is a slight curved lip on the edge of the plate.

I am thinking that any unflatness in the plate can cause uneven contact with the negative, the screen or even the printing paper. I will have to figure out a better way to cut down the plates without getting any distortion of the metal.

I want to practice getting those bugs out a little bit more before I commit to start making my own digital negatives.

Here's the two proofs I pulled last night with the plate next to it.



I think I remembered why I love printmaking so much. Too bad I suck at it.