Basic Question about Subbing
I was tinkering around trying to use hide glue as a substitute for "gelatin". Using it, I've been able to see some parts of the emulsion making process work. It works okay with a porous surface like paper, but the glue is water soluble. Sooner or later, that gelatinous glue is going to dissolve in water.
Further, I was trying also to coat it onto an acetate base. This leads me to my basic question: how do you get the emulsion to stick to the base?
It needs to receive water to get the developer to the silver nitrate crystals. It needs to repel water to keep from falling apart in the developing tank. How is this done?
I read around some, and I came across the threads which mentioned silane. Someone got an emulsion to stick to a smooth water-repellent surface without silane. How did they do it?
I also came across ideas like, the sub layer of emulsion should be mixed with an organic solvent that will eat into the acetate. I tried denatured alcohol; I got a whole lot of nothing.
I considered the idea that maybe the entire emulsion should somehow be bound in a transparent adhesive, but that won't allow a developer access to the silver, will it?
Also considered mechanically scratching or roughing up the acetate with sandpaper, to create a rougher surface; irregular scratching will only lead to a drop in clarity, I think. Smoothness yields gloss and transparency.
So, how have you done it? Is the magic in the choice of the gelatin?
I notice that sometimes there seems to be a propensity for us to fall in love with obscure and hazardous chemicals that cost $2000 per 100mg. If you're answer is one of those, Lucy, You've got some 'splaining to do!
How do you get your emulsions to stick to acetate and still survive the usual black and white development process? Thanks. J.
There is a thread here somewhere that describes subbing for acetate. Many of them use a mix of gelatin, acetic acid, and amyl alcohol. Offhand I would have to look one up. Both acetate and estar can be made receptive to gelatin by using electron bombardment to give it an electrostatic charge.
As for glue, I guess it can be used, but due to color and odor it is not in the running. Hide glue is probably also to be considered an active gelatin product. As such, it will sensitize and fog the emulsion depending on activity.
You can probably harden it with a photo hardener such as chrome alum or glyoxal.
A friend of mine, who works with cabon prints on glass, found that a sub coat of gelatin hardened with glyoxal is the best way to get carbon tissue(gelatin based) to adhere to glass. I no know nutin' 'bout no acetate.
Bill, all of my former Kodakers say that chrome alum is better for glass. I have had consistant reticulation with glyoxal, but none with chrome alum.
Just a heads up.