While Kae was making a plate, she commented on the fact the silicone she uses in Japan does not smell of vinegar. Hmm? Very early in my research into my waterless litho process, I had tried a number of different silicones that were available, and one promoted as neutral cure was one I used. It was different than the usual acetic acid producing types on curing, but it just didn’t seem as good for coating plates. I had a cartridge in my freezer with an expiry date of 1995. It was still soft inside so I made up a small diluted batch and coated it on screen emulsion, same as I had originally tried in the simplest approach to making positive waterless plates using common acidic silicone. I had never tried any NC silicones in my research for positive plates as I had already decided that Dow Corning produced the best common caulking silicone for coating toner washes and other imaging materials. The 1995 silicone is very viscous and meant more for gluing rather than sealing it seems, and harder to dilute. Besides it and other neutral cure silicones are not readily available even to this today. I have managed to find another good new neutral cure silicone that works for the positive plates.
The problem with this direct and obvious method of making positive waterless plates is that the common acidic silicones I was using would not bond well to the plastics and other compounds in the screen emulsion. This seems to have been a common problem even for the major companies developing their commercial plates.
Jerry Larson, the 3M chemist who had been heavily involved with the development of the first waterless plates was a great help to me as we tried to come up with an easier way for students and printmakers to produce plates than the complicated method I had been using. The commonly available silicones in North America all have the problem of not wanting to stick to plastics and this prevented reasonably lasting printing plates.
With the idea of using neutral cure silicone, I started to do research again on a simpler process, but keeping fine detail as well as commercial plates. In the end I have got excellent results with detail rivaling commercial plates - with no expensive developers to buy.
I recycle my plates so I calculate that it costs me about 23 cents to make a plate instead of 23 dollars for a plate and developer of commercial products. Any plates I make in a batch will keep for a year, just like my early ones; so an hour of production will give me about 25 plates. I can use photo plates to my hearts content!
Kae has gone back to Japan with knowledge of the new process. It turns out that Neutral cure seems to be the more common silicone available there, so it was natural for her to use in on her plates.
If enough printmakers are interested in learning more about the new process, let me know and I will write up a paper for the web; otherwise it is just not worth it for me to do if there is no great interest.
Right now printing an edition using my new developed method. Just like with anything, a change for the better can bring new problems as well. Now there is a new safer solvent to remove ink and other techniques involved to make multiple use of the same plate.