emulsion on glass: wetting agent or not...
my girlfriend is trying making her own glass negatives, using FOMA emulsion.
first try went well - not a problem with the emulsion adhering to the glass, but of course it wasn't perfect (which she is'nt after).
there was these small "black holes" in the plate.. which was expected (cleaning issues?), but then she tried. after reading the silver Gelatine book, that adding wetting agents to the emulsion, this could be helped...
so she did anf what happened? it looked fine in the developer (but the sensitivity of the emulsion was much slower that without the wetting agent), but as soon as she put it in the stop bath (palin water) the whole emulsion frilled and "left the scene"...
could it be because of difference in the temperatures from the developer and the water? (the water was much colder than the developer) or is there some other thing we missed?
tips highly appreaciated.
I had the same experience. The second time I coated glass, I added wetting agent (Photo Flo 600). After a few minutes in the developer I lifted the glass to look at it and it was crystal clear. I think I said something like "oh crap, did I leave the lens cap on?" when I saw the most lovely and perfect 5x7 sheet of emulsion in the tray. It was so strong I picked it up by the corners and finished the processing. I then spread it out and dried it on a piece of Yupo synthetic watercolor paper. I figure I'm half way to figuring out emulsion transfer!
But, back to the question. I now use Everclear 190 proof alcohol as a surfactant. It seems to do the job without aggravating frilling and lifting. One caveat is that I suspect most of these kinds of issues are very recipe specific. I've never used FOMA emulsion.
And, it's probably a good idea to try to keep the solution temperatures fairly constant through the processing.
If you're frilling during processing, I think you need to harden the emulsion. Wetting agent will only help with getting a smooth coating, and not with the frilling.
If you're using glass plates, my understanding it that you want to use chrome to harden the emulsion. There's two ways to do this, one by adding some chrome alum to the emulsion right before you coat the plates, and then in your processing solutions, use a chrome harding stop bath. Try Kodak Hardening stopbath SB-3.
I would second the advice to add a small amount of grain alcohol to the emulsion to help it flow better.
You might also consider subbing the edge of the plate with albumen (or a silane compound) to help the emulsion adhere better. Take a cotton swab, saturate it with egg albumen, run it along the 4 edges of the plate so that it coats a line about 2-3mm wide, and after it dries, coat the plate so that the emulsion contacts the albumen. This works well for wetplate collodion emulsions and I suspect the FOMA emulsion would also stick to it.
in my mad scientist days i tried to use albumen as a subbing agent with
Originally Posted by smieglitz
glass plates, but unfortunately since liquid light emulsion is gelatin based, it didn't work well at all.
i never used fotoflo or a grain alcohol or a hardener, but i learned
that a nice layer of gelatin ( or if you don't mine yellowing in a few years,
poly urethane ) as a sub usually kept my emulsion stuck to the glass.
my chems were usually all about 65-68F .
i also liked using a nice gooey layer of rubber cement mixed with flexible collodion ( pharmacy grade )
THAT was a lot of fun too, as long as there wasn't an open flame nearby
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the problem is, that without the wetting agent, there is no frilling at all...
Originally Posted by Kirk Keyes
but with it - it left the plate..
Stine has since risen the temperature on the stop bath, and it helps a lot..
I think I am unable (or almost) to get crome alun here in Denmark. (very strict laws you know)
PS: Can one get a photography asylum somewhere? :rolleyes:
Which wetting agent are you using? How long did you let the plates dry?
Can you order from Photographers Formulary? They most likely could ship you some chrome alum.
Anyway, the frilling is going to be hardening related.
Originally Posted by Kirk Keyes
I can't tell if you mean that frilling is in part influenced by hardening or if you mean hardening, rather than the surfactant/wetting agent, is the only factor in frilling.
If you mean the only factor, I have to disagree. It is my experience with 13 (I just checked my notes ) coating sessions covering four separate recipes with permutations of each, that the wetting agent is very much a factor in emulsion lifting. And, for my currently favorite recipe developed in pyro (the one on TLF) I use no hardener.
Also, I would recommend caution regarding blanket statements if we don't know the ingredients in a given commercial emulsion. I made something amazingly like Flubber once when I started recklessly adding ingredients. Now, believe me, I'm not saying one shouldn't experiment, but there's probably not a one-size-or-ingredient solution for all situations. I think in this stage of our personal experience with emulsions, we can offer suggestions, but not 'solutions'.
Originally Posted by Kirk Keyes
I don't know photographers formulary, but I don't think it matters.
most compagnies I know of are reluctant to say the least about shipping out of country...
Anyway - after some tries, Stine has found, that the thickness of the emulsion applyed on the plate AND the temperature of the water has a lot to do with the result.
Stine likes the plates to frill - as long as most of it stays on the plate.....
she is not trying to do emulsion lifts, even though that might be her next project..................:rolleyes:
Photographers Formulary - send them an email and see if they can ship to you. I'm sure they will konw if they can. http://www.photoformulary.com/
Anyway - what exactly are you using for "wetting agent"? I'm not sure anyone can really help without knowing what is being added to the emulsion. Are you adding Photo Flow, or alcohol or what? We can made suppositions all day but it does no good to guess...
I suggest adding chrome alum as it should harden the emulsion, decreasing it's propensity to swell during processing and when going from baths of varying temperatures. Also, chrome supposedly has some property that allows it to adhere to glass.