How can I test emulsion 'adhesion' to a polyester base?

[rmazzullo]

Hello all,

I have located different sources of polyester film which is listed as having a print receptive - or in some cases - hydrophilic coating. I am waiting for samples to arrive for testing and minimum order information . Using an inert gelatin emulsion (without silver nitrate), how do I test to see how well the set and dried test emulsion will adhere to the substrate? Should I use an inert emulsion with hardener and surfactant added to act more like an active emulsion?

Your thoughts / insight are appreciated.

Thanks,

Bob

 

[mshchem]

https://www.instron.com/en-us/

 

[mshchem]

You could try using a wide package tape, that's probably sticky enough to pull emulsion off PET. I wonder if EK sells PET extruded films?

 

[_T_]

I don’t understand why you wouldn’t test with the actual emulsion you are interested in. I wouldn’t leave anything out and then find out later on that it makes a disastrous difference.

As for the testing it depends on the conditions you expect the emulsion to encounter.

Mshchem said packing tape. That’s a pretty extreme test. Do you expect your emulsion to have to endure something like that?

Is it going to be handled by conservators with white gloves or is it going to have to endure touching and scratching with un careful hands?

It’s the same kind of thought process you need to use when testing for any work of art. My watercolors would be destroyed if they got wet and they would smudge if they were handled improperly but I don’t worry about that because they’re up on a wall and not being handled. My ceramics will chip or shatter if I drop them but that’s their nature so I don’t drop test them.

 

[koraks]

how do I test to see how well the set and dried test emulsion will adhere to the substrate?

Pour some gelatin emulsion with a hardener onto it, let dry and then flex the film. Leave it to sit on your desk for a week or so, so it goes through some day/night heat/cool cycles. If the emulsion stays in place, then try and run the film through a process that emulates regular film processing: i.e. an alkaline first bath for a few minutes, and acidic 'stop' bath for a minute, and then some more wet steps that emulate fixing and washing. Watch for the emulsion to reticulate and/or peel off of the film. If it doesn't do this, you're good.

You may find that without prior treatment, the emulsion doesn't adhere particularly well. You may have to sub the film first, which can be done by running it through a very dilute solution of gelatin (let's say 0.5% w/v or so). Harden this subbing coating, then coat on the regular emulsion. However, I'm probably telling you stuff you already know at this point.

I don’t understand why you wouldn’t test with the actual emulsion you are interested in.

Cost of esp. silver nitrate and the mess it makes. There's no real need for it, either. Besides, a test emulsion can be colored with a dye or even a dispersed pigment to make it easier to see what's happening.

I wouldn’t leave anything out and then find out later on that it makes a disastrous difference.

Of course at some stage the actual working emulsion will have to be tested, but if someone's going to coat film at home, they're going to automatically run into that step. I don't know many people who would start with some inert tests and then immediately proceed to coating several hundred square feet of functioning film. You always start with a test batch, see how it works, adjust materials & processes, etc.

 

[Jacro]

Hello all,

I have located different sources of polyester film which is listed as having a print receptive - or in some cases - hydrophilic coating. I am waiting for samples to arrive for testing and minimum order information . Using an inert gelatin emulsion (without silver nitrate), how do I test to see how well the set and dried test emulsion will adhere to the substrate? Should I use an inert emulsion with hardener and surfactant added to act more like an active emulsion?

Your thoughts / insight are appreciated.

Thanks,

Bob

Have you considered using subbed acetate instead?