No, I didn't bother. I did find that reducing the amount of THF solvent (aka pipe glue) to a ratio in the 100:1 (acetone:glue) range helped to keep the PVC relatively clear. Since the PVC was a mistake by the purchasing department (me) I was anxious to move on when I received the acetate.Back to the PVC.. have you considered (stabilised) chloroform?
The wrinkling was ocurring somewhat during coating the subbing but moreso during coating of the gelatin. Over the last few evenings I did a few more practice gelatin runs with 3 mil acetate rather than 5 mil on Denise's suggestion. There were a few issues I had to work out. I did find that in most cases the wrinkling would reduce as the gelatin dried.Is this 'wrinking' occuring during coating, or during/after drying?
One was temperature. Pouring out gelatin that was too warm on to room temperate acetate (fastened to the glass) caused wrinkling as the acetate would pull away from the glass.. Now, I was heating gelatin in the microwave and possibly making it too hot. So I switched to warming the gelatin in 15 ml batches a small stainless cup in 40C water. I also started warming the glass with warm air to about the same temperature. This made a big improvement.
Second was the amount of acetone in the subbing. For the diacetate film, less acetone seemed to do the job just as well without softening the diacetate as much. I had started with the acetone amounts called for by Wall or Kaszuba and reduced this down to about 25% of the original amount and the subbing still appears to work just as well. I haven't put any of this through a complete "processing" cycle but I don't see any difference in adhesion. I can roll it, bend it, twist it and the gelatin stays put. Maybe this is a difference between diacetate and triacetate, IDK.
Third was attaching the acetate to the glass prior to coating. I had simply been taping the acetate to the glass. That isn't what you want to do. (I did read somewhere about using a "stickyback" and moved in that directly.) What I worked out was to spread subbing on the glass, using a cotton ball or paper towel - either works, and then using a squeegee to work out the air bubbles and "glue" the acetate down to the glass. I start at one end of the acetate and glue down about a third of it and then do the rest, working the bubbles out along the way. My squeegee is a windshield wiper glued to a wood block, but I guess you could use anything.
Once the acetate is stuck to the glass, sub the top surface and let that dry for a minute or so to let alcohol and acetone evaporate. Then tape down the edges of the actate to keep it in place. The acetone and alcohol in the subbing solution will dissolve the tape (at least the tape I am using) if you try to tape it before applying subbing. It makes a mess.
One variation on the above I tried to apply the subbing was to spread subbing over the acatate and then use the squeegee to remove any excess. this leaves a really nice looking piece of acetate ready to coat and adhesion seems to be good. Unfortunately the subbing solution attacks the rubber winshield wiper. In the end there didn't seem to be any real difference once coated with gelatin. IDK if I will end up with subbing lines or not.
After getting this worked out last night, I set up one final piece of acetate and coated some real emulsion. Although I think my coating is too thin (unrelated problem - I had figured this wet coating to be about 8 mils but 12 seems to work better) it adhered nicely to the base. After drying overnight, it remained stuck to the base and looks pretty good. It'll be cut up and go in the camera today or tomorrow.
Denise also sent me a quantity of the pre-subbed melinex and I will be trying that as well. While I am sure the factory subbed stuff will be very nice, I want to be able to "own the whole process" just for fun.
Lastly, for what it's worth, the little stainless cups I mentioned above that I am using to heat gelatin, which I also use to hold weighed and measured chemicals, etc, come from the kitchen gadget section of Walmart. They are stainless condiment holders and you can buy a package of 4 IIRC for 88 cents. They hold about 35 ml. Work great!