Well, I'm back to write up some notes and observations. Maybe some of you can offer suggestions or at least it might help you to reproduce what I have done or go farther. A disclaimer here: I haven't yet used a 1M NaOH solution - the solution I'm using is 2.5M. Didn't have time to mix that up but it is on the docket. I did, however, run the current prep at about 100 F as mentioned in the paper cited above. I am running all tests right now with little bits of emulsion, but I am working on scaling up. My coating size right now would be about 6x7 cm. I have had two passing processing tests both after allowing the emulsion to harden overnight.

1) Hydrophilicity (if that's a word) of the PET is greatly increased. After the NaOH immersion and washing, I hang the sheet to dry. It literally takes an hour for the sheet of PET to dry.

2) Photo-Flo in the emulsion as a surfactant or in the PET wash (to avoid water spots - which probably doesn't matter) seems to be a disaster. Maybe the ingredients of the PF have a higher affinity for the PET than emulsion.

3) Adhesion when coating at room temperature (70F) is great until slitting the film. After slitting, when looking at the back side of the film, you can see where the emulsion has separated from the support. If you pick at it with a fingernail or x-acto knife, you can separate the support and emulsion. However, if you do not pick at it, the coating seems to pass the processing test. Using chrome alum as a coating time hardener (1 drop 10% CA in ~5 ml emulsion) seems to make no difference. I think this is a mechanical effect where the PET is more flexible than the emulsion. As an after-thought, I've had this same problem when coating 3M base at too low a temperature and I believe others have mentioned this as well. Denise gave me a coating temperature of 32.5C (~90F). I believe PE has mentioned 100F in the past.

Next actions:

a) Try coating with support at 90 - 100F. This ought to reduce the viscosity of the emulsion and make it easier for it to grab onto the micro-pores in the PET.

b) I have read in other postings about using ethanol as a surfactant. That's something else to try. QUESTION: Can IPA be used as a surfactant? I have lots of that. Everclear is NOT available in Pennsylvania but I am told I can use vodka.

c) a "lights out" coating and exposure in camera. If I can get a coating close to 6x9cm, I plan to expose it in my Kodak Tourist. It's 1940s lenses probably don't have the UV blocking properties of newer lenses (just guessing here) and I also think this would be the easiest camera to use, now that it is back in commission.

So some problems to work out but I've consistently gotten farther with the PET than other subbing methods I've tried. Oh, I also had a question of why not just use the 3M film or Melinex? Because I am looking for an inexpensive off-the-shelf solution and it's fun.

Stay tuned,
Jason