To all of our chemists and emulsion makers out there, as you might have read in some of the other postings, I have been trying to develop a method to coat emulsions on PET. Mostly it seems to work but I am trying to solve a problem regarding frilling at cut edges. In other words, everything is great until I try to slit the film sheet. Then I get frilling while processing. Frilling is worse in XTOL than plain water, so I believe that pH has something to do with this.

I believe I need to add a hardener, which I have resisted because of problems I've had with hardener and coating. Normally adding a drop or two of 10% Chrome alum turns the 10-20 ml emulsion I'm working with into glop in just a few seconds. So, obviously too strong. Trying to add very minute quantities gives not much or any effect. Done many a search through these archives and am now more confused yet! So I will put my question out there as a tongue-in-cheek textbook style question. These drive my kids nuts cause I do it to them in the car all the time.

Jason is working on coating 100 ml of an emulsion made with 8% gelatin on a 5 mil support. 5ml of 50% ethanol (aka vodka) has been added to the gelatin as a surfactant. He is having problems with frilling at cut edges when processing exposed film in XTOL. Jason has decided to try adding a hardener. He has chrome alum (CA) available. To add CA hardener to 100 ml of emulsion to be coated at 32.5 C,

A) Jason should mix a CA solution of what percentage?

B) How much of this solution should be added to the emulsion before coating?
So, no looking at your neighbor's paper. Pick up your pencils - - - begin!

Thanks for your help, Jason