How fast can a simple emulsion go?

Ive been making the ostermans silver bromide gelatin formula for a year and im curious if it could ever get to iso 3 or 6 without sulphur or gold or by using ammonia. More for curiosities sake than any motive to avoid sulphur/gold. I'm interested in practicle simple steps rather than making it far more complex.

I *think* I've got it from iso .75 to iso 1.5 by a syringe pump set to a 20 min precipitation instead of the instructions which I think from memory are 3x 1 min precipitations of the silver with a 1 min holds. Everything done at 55deg with a 300rpm stirrer. then hold for 20 mins as per instructions.

I did recently try to rig something up with my syringe pump so that it pumpped air into a test tube of silver nitrate in a water bath which then made the heated silver nitrate siphon off up another tube into the gelatin at a nice constant 55deg c. Unfortunately the plates fogged very badly. I'm not sure if it was the precipitation itself or maybe the tubing used etc that caused the issues

I'm wondering if any neat tricks could be employed in the precipitation / holding or maybe even the spinning peanut could be hindering crystal formation.?

I have an old book on emulsion making that had a chart of grain size Vs precipitation speed and it seemed to be a fairly significant increase in crystal sizes with very slow precips I don't really see any formulas that employ a very slow precipitation. My own findings seem to show it maxes out at iso 1.5.

There's lots a talk about the post wash heating making a bigger speed increase but my slightly dubious testing has indicated a 44 min post wash cook made absolutely
no difference, I'm wondering if it's ineffective without sulphur/gold/active gelatin?

Substituting ammonium bromide for potassium bromide (adjusted for equivalency) just about doubles the speed of a plain silver, no gold/sulfur emulsion. Adding erythrosin to make the emulsion orthochromatic bumps up the speed a bit more (if you don't use a yellow filter.)

http://www.thelightfarm.com/cgi-bin/htmltutgen.py?content=15Jun2013

btw: You really should be seeing an increase in speed when you ripen (heat) the washed noodles, although not necessarily huge.
Word of advice: keep it simple.
Good luck and fun.
d

Going up to 60C or 65C can increase speed as can an increase in hold time after precipitating the Silver. All of these actions can increase speed, contrast, grain - and fog.

PE

dwross said:

Substituting ammonium bromide for potassium bromide (adjusted for equivalency) just about doubles the speed of a plain silver, no gold/sulfur emulsion. Adding erythrosin to make the emulsion orthochromatic bumps up the speed a bit more (if you don't use a yellow filter.)

http://www.thelightfarm.com/cgi-bin/htmltutgen.py?content=15Jun2013

btw: You really should be seeing an increase in speed when you ripen (heat) the washed noodles, although not necessarily huge.
Word of advice: keep it simple.
Good luck and fun.
d

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Thanks! I think I will try swapping the sodium bromide for ammonia bromide next time. I just need to get my mathematics head on to work out the mol weight equivalents !
I will have to try the post wash cook again. I made a test plate before and after the 45min cook and the results where identical. I will test again.
Kind regards
Matt

Photo Engineer said:

Going up to 60C or 65C can increase speed as can an increase in hold time after precipitating the Silver. All of these actions can increase speed, contrast, grain - and fog.

PE

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Thanks! I might try those suggestions one at a time to see if I can squeeze a little more speed. As long as I don't get fog! Recently Ive been putting drops of emulsion onto some cotton rag paper so I can do a min/max density checks at various points of the process to see when and where fog occurs.

Short answer is yep. Let it ripen longer after washing, checking for fog along the way.

Be careful about testing on paper. I’ve found you can get false results because the emulsion interacts with some papers. Better to test on glass.

The speed will depend on the gelatin you use as much as anything. Bostick and Sullivan gelatin will let you get faster. So will using food grade gelatin

Denise and PE both have great advice!

Nodda Duma said:

Short answer is yep. Let it ripen longer after washing, checking for fog along the way.

Be careful about testing on paper. I’ve found you can get false results because the emulsion interacts with some papers. Better to test on glass.

The speed will depend on the gelatin you use as much as anything. Bostick and Sullivan gelatin will let you get faster. So will using food grade gelatin

Denise and PE both have great advice!

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Thank you, I’ve some leftover emulsion in the fridge. I might have a second attempt at ripening after the wash.
I’m having a real hard time getting past iso 1.5. I just tried adding 0.1% hypo a few hours ago and that fogged extremely badly past 15 mins hold. I can make perfect iso .5 - 1.5 at least

Without Sulfur or Sulfur + Gold, you are going to be hard pressed to get past about 6 - 12. With them you could get to 25 or 50, and with Ammonia you could make it to 100 with experiments.

Keeping with B&S Gelatin might present problems as might food grade Gelatin. Be wary of variations between batches as well.

Paper tests on blotters works well. Doing these tests on glass minimizes the visual appreciation of fog but a paper based test will show it up clearly. The first sign of fog on a paper test will probably be fog free on film.

PE

Photo Engineer said:

Without Sulfur or Sulfur + Gold, you are going to be hard pressed to get past about 6 - 12. With them you could get to 25 or 50, and with Ammonia you could make it to 100 with experiments.
PE

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Truth.

wirral_matt, question: Besides for the fun challenge, why do you want to go faster? It sounds like you can already make a lovely emulsion. The fastest you'll be able to achieve with a plain silver emulsion will still require a tripod, so embrace the slow!
If you really need to go handheld, or stop some motion, I have recipes for ISO 25 to 50 emulsion, and 100 (summer speed) here: https://www.blurb.com/books/6465389-the-light-farm
Be aware, however. Although not particularly complex, when you start using ammonia and sensitizing chemicals, you're playing a different game.

dwross said:

Truth.

wirral_matt, question: Besides for the fun challenge, why do you want to go faster? It sounds like you can already make a lovely emulsion. The fastest you'll be able to achieve with a plain silver emulsion will still require a tripod, so embrace the slow!
If you really need to go handheld, or stop some motion, I have recipes for ISO 25 to 50 emulsion, and 100 (summer speed) here: https://www.blurb.com/books/6465389-the-light-farm
Be aware, however. Although not particularly complex, when you start using ammonia and sensitizing chemicals, you're playing a different game.

Click to expand...

I love shooting slow and always use a tripod. I'm shooting portraits and I've found iso 1.5 just isn't quite fast enough for sensible exposures all year round. Personally I feel iso 3 would be ideal and iso 6 golden.

I'm hoping with a few minor tweaks I can get to iso 3 or 6 without resorting to sulphur or ammonia. I don't want to go too far down the rabbit hole of gelatin dryplate chemistry, but I'm just a tiny bit too slow. Hence my mission to try and make the simplist change I can to get an extra stop or two.

I've got your book I can make the basic emulsion in it great. I've only made it once but it was iso 0.5 on my attempt although admittedly it ended up.a bit of sla hybrid with osterman formula. The osterman sodium bromide formula I managed to get to iso 1.5 but I've had a lot more experience with that recipie.

Make the Osterman formula and add 0.3 mole % iodide just before coating. Hold 15 minutes at 40C or 105F and then add your finals and coat.

See if that helps.

Of course, spectral sensitization will help a lot.

PE

Photo Engineer said:

Make the Osterman formula and add 0.3 mole % iodide just before coating. Hold 15 minutes at 40C or 105F and then add your finals and coat.

See if that helps.

Of course, spectral sensitization will help a lot.

PE

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That sounds good, I might try that tonight with some basic emulsion I have in the fridge.
I'm a bit unfamiliar with the terminology "0.3 mol %" potassium iodide ? Im thinking of testing 60g of ostermans emulsion tonight.

Look up molar mass calculations. PE is indicating adding KI in the amount of 0.3% the molar mass of silver (not silver nitrate) in your 60g sample.

wirral_matt said:

I've got your book I can make the basic emulsion in it great. I've only made it once but it was iso 0.5 on my attempt although admittedly it ended up.a bit of sla hybrid with osterman formula. The osterman sodium bromide formula I managed to get to iso 1.5 but I've had a lot more experience with that recipie.

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Recipes (paradoxically, especially the simple ones) fall apart if they aren't followed closely. If you change ingredients and/or timing and/or temperature, you've got yourself a new recipe. AmBr-O will get you to 6-12 at summer UV levels. Avoid the temptation to "modify" recipes and use Kodak HC110 to start with. Developers greatly influence speed. If that doesn't get you where you want to be, ammonia may be in your future.

dwross said:

Recipes (paradoxically, especially the simple ones) fall apart if they aren't followed closely. If you change ingredients and/or timing and/or temperature, you've got yourself a new recipe. AmBr-O will get you to 6-12 at summer UV levels. Avoid the temptation to "modify" recipes and use Kodak HC110 to start with. Developers greatly influence speed. If that doesn't get you where you want to be, ammonia may be in your future.

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If I get iso 6 from ambr-o I will be super happy. When I tried it it was a really nice emulsion in its results. It's a great book btw.

Im going to try a few things suggested with my current emulsion as I've got a bit left. Failing that I'll give ambr-o a serious attempt.

Nodda Duma said:

Look up molar mass calculations. PE is indicating adding KI in the amount of 0.3% the molar mass of silver (not silver nitrate) in your 60g sample.

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Thanks! That makes sense. I can do that tonight, coat some plates and test it tommorow. I'll yet you know how it goes.

Just a heads up to say everything’s gone pear shaped. I tend to find if I’m doing an experiment which takes a long time to do and needs some accurate clean results, everything that can go wrong will go wrong. The iodide emulsion looked promising based of the min-max fog check on cotton rag paper but I made 30grams instead of my planned 60g basically so I could try more things with my 120g of leftover master emulsion. I poured that on onto a glass plate and it went down my arm twice! I don’t even know what went wrong with the post wash cooking test but it fogged, I think it may of been a new digital scale I used which had a blue lcd screen which I didn’t anticipate untill I switched it on. It fogged at 0 mins so certainly not caused by the cook.
I made some more emulsion last night and sustited Sodium Bromide for ammonium Bromide, I will try that later and see what new mistakes I can make.

Reports from the field are always interesting and welcome, but if you'd like constructive feedback, more details are necessary. What halide did you start with, for example. Why you decided to change them out. Silver isn't cheap and you can waste a lot of money casting about. If speed is your goal, embrace the ammonia .

That blue light would have to be mighty strong and close to the drying emulsion to cause more than a little fog with a slow emulsion. A little fog is not undesirable in a slow, contrasty negative emulsion. Shouldn't cause you concern if it's the price you pay for a little more speed.

Ok, I think I have success. I’ve not fully tested my iso but the stouffer stepwedge contact print I’ve just put in the wash is clearly showing more steps than usual. Possibly iso 3-6. I think I found this a bit of a nightmare as I usually use a sodium Bromide emulsion. To gain speed a swapped that to the equivalent ammonium Bromide in order to gain speed based upon a recomendation in this thread. My iso speed then dropped even further. I then tried ambr emulsion because it’s tried and tested and again it was iso 0.5. I then made a few more very slow ammonium Bromide emulsions and then bought more ammonium Bromide from a more reputable supplier (my previous was from ebay) and instantly it looks like I’m getting more speed when I made Dwross Ambr emulsion again with my new ammonium Bromide. I feel I can go back to taking photographs again now. Thanks for the help! Lesson of the day, avoid ebay chemicals if at all possible!

Congrats! Good news. "ebay chemicals" is a lesson we all learn . Happy photo'ing! If you're in the northern hemisphere, your ISO speed will start to decrease as we move into winter, but winter days can be some of the most lovely to photograph. Stay consistent with your recipe. Take good notes about dates, time of day, locations, light conditions, and anything else that you think is important, and after one year of photographing with your emulsion, you'll know it like the back of your hand and have your own personalized data sheet to refer to when needed.

With one of the small pump setups like Ron has described in the past, I've gotten somewhere between ISO 125 - 160 with sulfur thiocyanate sensitization. But this starts to get into more precision control and becomes a chemistry project with arduinos and software and all that kind of thing. Don't know if I could reproduce it right now, but it's possible.

If you are interested in some reading and research, RIT (Rochester Institute of Technology) has published past master's thesis on-line from their school of photographic science. Back in the day, a good number of people did thesis' on emulsion experiments. Most give the preparation methods they used. Minus the fancy equipment like spectraphotometers that you don't need to make the emulsion, most of these equipment set-ups can be replicated by the home experimenter with some creativity. The fancy machines are need to quantify your results in a research setting, but if you just want to "fool around", most of it is pretty workable.

kb3lms said:

With one of the small pump setups like Ron has described in the past, I've gotten somewhere between ISO 125 - 160 with sulfur thiocyanate sensitization. But this starts to get into more precision control and becomes a chemistry project with arduinos and software and all that kind of thing. Don't know if I could reproduce it right now, but it's possible.

If you are interested in some reading and research, RIT (Rochester Institute of Technology) has published past master's thesis on-line from their school of photographic science. Back in the day, a good number of people did thesis' on emulsion experiments. Most give the preparation methods they used. Minus the fancy equipment like spectraphotometers that you don't need to make the emulsion, most of these equipment set-ups can be replicated by the home experimenter with some creativity. The fancy machines are need to quantify your results in a research setting, but if you just want to "fool around", most of it is pretty workable.

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That sounds interesting! I might have a quick search for that later. I quite like reading all I can on the subject whilst trying to be mindful not to go too far into the chemistry.

Slightly off-topic, but I wanted to thank two contributors to this thread for publishing books on emulsion making.

peoplemerge said:

Slightly off-topic, but I wanted to thank two contributors to this thread for publishing books on emulsion making.

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Thank you. I can't deny that's nice to hear. Writing books on these kinds of subjects is always a labor of love, but still a lot of work. I'm pretty sure I can speak for Ron Mowrey ("PE"), too. Appreciation is coin of the realm .

Thank you for the comment. Writing is not easy, but I'm trying for it a second time. The going is rough. It is tougher this time.

Best wishes to you too Denise.

PE