HELP WITH DRY PLATE!

[Christopher Gio]

Hi im new here, i frequently lurk but just recently made an account here.

Im currently trying to make my own Dry Plates, and its honestly a frustrating process. I have made 3 batches and all of them failed. The first two was based on Mark Ostermans formula. It had little to no density & even exposing for 8 minutes only gave a very transparent image.

The last batch was made using Kevin Kliens basic emulsion from TFL. It was completely black. I dont think it was exposed during processing because im pretty careful about that & i do use my darkroom for printing & it has never fogged a paper. I dont really know what im doing wrong. Maybe its the emulsification process of the gelatine? Is the magnetic stirrer mixing to hard? Am i adding the silver too fast/too slow (the first two batches was 3 minutes & the last batch i tried 4 minutes)

So do any of you have any tips for making dry plates? Any help would be welcomed

 

[koraks]

Welcome to Photrio!

In anticipation of some more experienced emulsion makers, let me highlight a few things. There are so many things that can go wrong with a DIY emulsion...I think it would be useful if you described, in detail, how you made each of these batches of plates.

As to fogging: light can of course fog a gelatin emulsion, but so can chemical agents. For instance, any source of sulfur or sulfides (possibly in the gelatin if it's insufficiently pure) will fog an emulsion. The formula you used (the Kevin Klein one from TLF) specifically calls for photo grade gelatin. What kind of gelatin did you use? Also, the 0.2% addition instead of 0.02% of thiosulfate may be part of your problem. This addition is a form of sulfur-sensitization and if overdone, it'll fog the entire emulsion. I'd give it a try with the lower 0.02% sensitization and just accept a (much) slower emulsion at least for an initial test. The fact that you got no fog (but a slow emulsion) with the Osterman formula implies that some of the variation is due to the formula you've used or changes in working methods. That should give some clues, at least.

As to fogging due to light: drying a gelatin emulsion takes quite some time. Even a low level of fogging light will produce a large amount of fog if the exposure is long enough. You mention your darkroom is safe for paper, but when using B&W paper, it's usually only out in safelight conditions for a couple of minutes. Your gelatin emulsion will likely have spent far longer than this in your safelight conditions, and your plate emulsion may be significantly faster than paper as well, depending on the formula used. I'd start by doing a safelight test with B&W paper, but leave the paper out in safelight conditions for an hour or so. There's a good chance that the safelight you assume to be safe for B&W paper is really not safe for the work you're doing with it.

 

[BrianShaw]

LOL, I hope I’m not the only person who doesn’t know the answer… but what is TFL, or TLF? IDK THX.

 

[Christopher Gio]

LOL, I hope I’m not the only person who doesn’t know the answer… but what is TFL, or TLF? IDK THX.

Hahahah sorry its supposed to be TLF, TheLightfarm. A pretty comprehensive (Albeit jumbled) website for silvergelatine making

 

[BrianShaw]

Thanks very much. Now I can stop fixating on that and read the rest of the post.

When you respond to Korak’s question about gelatin used, please mention both the grade and the bloom number. In other gelatin-based applications I’ve noticed that too soft or too hard is sometimes problematic. I don’t know offhand if photograde implies a specific hardness or is primarily a purity rating.

 

[Christopher Gio]

Welcome to Photrio!

In anticipation of some more experienced emulsion makers, let me highlight a few things. There are so many things that can go wrong with a DIY emulsion...I think it would be useful if you described, in detail, how you made each of these batches of plates.

As to fogging: light can of course fog a gelatin emulsion, but so can chemical agents. For instance, any source of sulfur or sulfides (possibly in the gelatin if it's insufficiently pure) will fog an emulsion. The formula you used (the Kevin Klein one from TLF) specifically calls for photo grade gelatin. What kind of gelatin did you use? Also, the 0.2% addition instead of 0.02% of thiosulfate may be part of your problem. This addition is a form of sulfur-sensitization and if overdone, it'll fog the entire emulsion. I'd give it a try with the lower 0.02% sensitization and just accept a (much) slower emulsion at least for an initial test. The fact that you got no fog (but a slow emulsion) with the Osterman formula implies that some of the variation is due to the formula you've used or changes in working methods. That should give some clues, at least.

As to fogging due to light: drying a gelatin emulsion takes quite some time. Even a low level of fogging light will produce a large amount of fog if the exposure is long enough. You mention your darkroom is safe for paper, but when using B&W paper, it's usually only out in safelight conditions for a couple of minutes. Your gelatin emulsion will likely have spent far longer than this in your safelight conditions, and your plate emulsion may be significantly faster than paper as well, depending on the formula used. I'd start by doing a safelight test with B&W paper, but leave the paper out in safelight conditions for an hour or so. There's a good chance that the safelight you assume to be safe for B&W paper is really not safe for the work you're doing with it.

Ah okayyy thank you soo much for your reply... Unfortunately im currently using foodgrade gelatine, im very limited in supplies here in indonesia, so im trying to make do with what i have...

I will try to dim my darkroom more & use a 0.02% hypo solution.

I think the main difference is the emusification. In the first two batches i mixed the silver nitrate solution into the gelatine at around 3 minutes? Whilst the last batch as per Kevin Klein's formula is mixed at around 10 minutes.

Hopefully i will try again next week...
Thank you @koraks for the insight

 

[Christopher Gio]

Thanks very much. Now I can stop fixating on that and read the rest of the post.

When you respond to Korak’s question about gelatin used, please mention both the grade and the bloom number. In other gelatin-based applications I’ve noticed that too soft or too hard is sometimes problematic. I don’t know offhand if photograde implies a specific hardness or is primarily a purity rating.

Hehe sorry, my bad, honestly wrote this thread out of desperation.

Yeah living in indonesia, i only have access to food grade gelatine at around 160-200 bloom gelatine

 

[BrianShaw]

I completely understand using available resources! As I mentioned, I can’t say that gelatin strength is your problem but quickly found that photographic gelatin is hard, 250 bloom. Maybe that’s for strength and stability in the final product???

This thread might yield some insight into the matter. It was written by a Kodak photographic engineer.

Gelatin Types

There are a many gelatin types for making silver gelatin emulsions and most current textbooks don't discriminate between them. Here is some terminology to help you out. 1. Food gelatin: These are active gelatins with lots of additives. At my current estimates as little as 30% of the...

www.photrio.com

 

[Christopher Gio]

I completely understand using available resources! As I mentioned, I can’t say that gelatin strength is your problem but quickly found that photographic gelatin is hard, 250 bloom. Maybe that’s for strength and stability in the final product???

This thread might yield some insight into the matter. It was written by a Kodak photographic engineer.

Gelatin Types

There are a many gelatin types for making silver gelatin emulsions and most current textbooks don't discriminate between them. Here is some terminology to help you out. 1. Food gelatin: These are active gelatins with lots of additives. At my current estimates as little as 30% of the...

www.photrio.com

Thanks for the link... So far i have been using pig gelatine and cow gelatine, havent really found a difference, besides the pig gelatine absorbing more water... I think i saw a store selling bone gelatine... Maybe thats a more standard way to go(?)

 

[koraks]

food grade gelatine at around 160-200 bloom gelatine

That doesn't sound optimal. While you can probably get away with a lower bloom gelatin, the problem with food grade gelatin for silver halide emulsions is the lack of purification, in particular from sulfur compounds. And this sulfur can (and will) cause fog. There's a good chance that this contributes to your problems, even if it's not the only possible explanation.

See also the link @BrianShaw provided, although it's relatively easy to find (much) more on the topic using Google.

I'm very skeptical of attempts to make a decently fast dry plate silver gelatin emulsion with a food grade gelatin.

 

[BrianShaw]

There are several gelatin industry associations, including one in Asia, that have some fantastic educational materials on their web sites. And a lifetime supply of academic material!