Ammonia digest emulsions

[Sparks n Fire]

Hi! I would really like to attempt to make an ammonia digest emulsion and would like to know if anyone here has any experience doing so. I've become pretty decent at making regular emulsions with dyes and sensitisers and would like to take the next step.
Any assistance would be much appreciated!
N.N

 

[ProfessorC1983]

I've had some decent success with ammonia after a lot of trial and error. The process of converting silver is pretty well-described in the literature and you'll quickly get the hang of adding smaller and smaller amounts until it's one drop at a time, then suddenly clears. Good ventilation is of course key.

I noodle wash about 90 minutes in 8-10 changes of filtered tap water, and add extra KBr before the second digestion, which helps control fog.

I'd recommend making your first batch without any dyes or sensitizers. For some reason, erythrosine seems to fog my ammoniacal emulsions quite badly, and I wasted quite a few batches before isolating that variable!

 

[Sparks n Fire]

I've had some decent success with ammonia after a lot of trial and error. The process of converting silver is pretty well-described in the literature and you'll quickly get the hang of adding smaller and smaller amounts until it's one drop at a time, then suddenly clears. Good ventilation is of course key.

I noodle wash about 90 minutes in 8-10 changes of filtered tap water, and add extra KBr before the second digestion, which helps control fog.

I'd recommend making your first batch without any dyes or sensitizers. For some reason, erythrosine seems to fog my ammoniacal emulsions quite badly, and I wasted quite a few batches before isolating that variable!

thanks for the tip about the erythrosine! ii probably would have added it. the main thing i want to know about is the precipitation times. over how long a duration do you add the silver? In denise ross's book on her TLF#2 recipe she says 'add half the silver solution. Continue stirring for 1 minute.' I need clarification on the wording because ive read other ammonia digest recipes that say to just dump the silver in in one go. Do you add the silver in over that 1 minute or is it being dumped in and then stir for 1 minute? I know with these things it make a big difference.
also, what sort of ISO are you getting?
thanks!

 

[ProfessorC1983]

Yes, silver addition time is one of the main variables that will determine emulsion speed and contrast. My goal is a high-contrast emulsion to use for making alt-process contact prints, so I use a very fast "dump" addition of 10 seconds with fast stirring (on a magnetic stirrer/hot plate), then turn stirring down to the minimum and hold for 20-30 minutes. All at 42-43C. That gives me about ISO 3-6 depending on the batch, with a very high gamma around 1.2-1.4 which suits making salt/kallitype/vandyke prints.

Slowing addition time will decrease contrast and increase speed. So all else being equal, adding the silver over 3-4 minutes you'd get higher speed and a lower contrast more suitable for making silver gelatin prints, if that's your aim.

I should also note that I tried Denise's TLF #2 recipe toward the beginning of my emulsion-making journey and for whatever reason I didn't have a lot of success with it. I seem to need a lot more iodide to get the needed contrast, so my current recipe is derived from a copy/process emulsion by Baker (1st ed, p.68). I've found his book "Photographic Emulsion Technique," and Ron Mowery (PE)'s book "Photographic Emulsion Making, Coating and Testing" to be valuable resources in addition to The Light Farm. There are also some useful recipes in the appendix of Reed and Jones, "Silver Gelatin".

Looking forward to hearing about your progress!

 

[Sparks n Fire]

im looking for something with fairly even contrast. Is that ISO the emulsion with no sensitisers?

I have Photographic Emulsion Technique saved but can't get access to Photographic Emulsion Making, Coating and Testing and id really like to read it. How did you get access to it?
N.N

 

[ProfessorC1983]

Yes that ISO is without any sensitizers. Certainly its speed could be improved by at least a couple of stops with slower precipitation and addition of sulfur/gold, but I've not yet tried as I'm happy with that speed for now (it's about 7 stops faster than my plain silver emulsions!).

You're right that the Mowrey book is not currently for sale anywhere. I was able to find a copy in a university library here in the US and had it sent to me via interlibrary loan. Send me a DM and I may be able to help.

 

[Sparks n Fire]

Yes that ISO is without any sensitizers. Certainly its speed could be improved by at least a couple of stops with slower precipitation and addition of sulfur/gold, but I've not yet tried as I'm happy with that speed for now (it's about 7 stops faster than my plain silver emulsions!).

You're right that the Mowrey book is not currently for sale anywhere. I was able to find a copy in a university library here in the US and had it sent to me via interlibrary loan. Send me a DM and I may be able to help.

ive not sent enough messages on this forum to be able to DM you :/ is there another way i can contact you?

 

[MattKing]

ive not sent enough messages on this forum to be able to DM you :/ is there another way i can contact you?

@ProfessorC1983 can send you a Private Conversation, and you can then participate in it. You can use that to exchange emails, if you so wish.
If you need to attract the attention of someone, typing their name with an @ symbol in front in a post (like I just did) should send them an alert.

 

[ThePhotoChemist]

I've had some decent success with ammonia after a lot of trial and error. The process of converting silver is pretty well-described in the literature and you'll quickly get the hang of adding smaller and smaller amounts until it's one drop at a time, then suddenly clears. Good ventilation is of course key.

I noodle wash about 90 minutes in 8-10 changes of filtered tap water, and add extra KBr before the second digestion, which helps control fog.

I'd recommend making your first batch without any dyes or sensitizers. For some reason, erythrosine seems to fog my ammoniacal emulsions quite badly, and I wasted quite a few batches before isolating that variable!

I had a brain-blast last night. I haven't *fully* confirmed anything yet, but I've got a theory.

I had issues with ammoniacal emulsions fogging a lot, and I always used erythrosine for them too. Regular ammonia-bromide emulsions seemed fine, at the time. But later on, I noticed that when testing gold/sulfur sensitization, I would get some pretty bad fog that would absolutely nuke the emulsion as the sensitization carried out.

I started to suspect my "safelights" might be leaking a little bit of green. I just use cheapy wifi RGB bulbs set to red. They never seemed to give me any problems in the past, but it's been a few years since I worked with paper or anything "normal". I started keeping them at 1% while taking samples, and turning them off entirely in-between, and the mystery fog disappeared.

Last night I was curious, and held up a $10 spectroscope to each bulb, and sure enough there was a good amount of yellow light in all of them, and a couple even had some green light visible.
None of this was scientific enough to really say the bulbs are the 100% culprit here, as I changed a bunch of other small stuff with my workflows at the same time. But it would make a lot of sense if this was the case.

I ordered some "deep red" LED strips off of eBay last night, and I'll update when I can test those out.

 

[Herzeleid]

I had a brain-blast last night. I haven't *fully* confirmed anything yet, but I've got a theory.

I had issues with ammoniacal emulsions fogging a lot, and I always used erythrosine for them too. Regular ammonia-bromide emulsions seemed fine, at the time. But later on, I noticed that when testing gold/sulfur sensitization, I would get some pretty bad fog that would absolutely nuke the emulsion as the sensitization carried out.

I started to suspect my "safelights" might be leaking a little bit of green. I just use cheapy wifi RGB bulbs set to red. They never seemed to give me any problems in the past, but it's been a few years since I worked with paper or anything "normal". I started keeping them at 1% while taking samples, and turning them off entirely in-between, and the mystery fog disappeared.

Last night I was curious, and held up a $10 spectroscope to each bulb, and sure enough there was a good amount of yellow light in all of them, and a couple even had some green light visible.
None of this was scientific enough to really say the bulbs are the 100% culprit here, as I changed a bunch of other small stuff with my workflows at the same time. But it would make a lot of sense if this was the case.

I ordered some "deep red" LED strips off of eBay last night, and I'll update when I can test those out.

I had similar experience with safe lights.

I was using a regular white led light with double rubylith tape over. It was safe for collodion work and regular emulsions (I have no experience with ammoniacal emulsions). But when I added eryhtrosine and did gold/sulfur sensitization, I started having more than acceptable fog. I switched to 660nm red led lights and it solved all my problems.

 

[brazile]

I had exactly the same experience as Serdar. My original safe lights had been fine, but as soon as I moved to ery + gold/sulfur, boom there was fog. Struggled with it until, as we say around here "dawn broke over Marblehead". Did the appropriate testing and found the culprit(s).

Robert

 

[ThePhotoChemist]

I just wanted to follow up - I think I did confirm my suspicions here, and that a few unsafe safelights were to blame.

The RGB wifi bulbs I was using do seem to give off light up through the 570-580nm region, and per the absorption spectrum here for erythrosine in bromo-iodide emulsions, it gives sensitivity down through about 590nm.

I ordered some deep-red led strings, but they seemed to be just as leaky as the bulbs I was already using. I did have a single bulb from a different brand that seemed to only output 700+nm, but honestly I'm just going to stick to proper safelights for the time being.

I've since dug up a proper safelight I had laying around - a very deep red Wratten Series 2 - and have made two of my fastest emulsions to date (Denise Ross's AmBr, not proper ammoniacal ones) back to back. I'm guessing any emulsion that was fast enough got fogged and scrapped, or at the very least, wasn't receiving the full gold/sulfur sensitization that it should have been getting if it made it to the plate.

So that's a mystery solved! Now I can focus on playing with proper ammoniacal emulsions!

 

[ProfessorC1983]

Wow, thanks so much for following up here. I suspect something similar may be happening to me. I did buy the $10 spectroscope and tested my red LED bulbs (single-color, not wifi-enabled) and the lines seemed to light up right at 600nm, but given the low resolution of the device, that feels a bit too close for comfort, especially since I often leave the "safe"light on while plates are drying. I'll invest in some real safelights and report back!