Taking the DF96 plunge

[Donald Qualls]

Pretty decent for zero equipment. What monobath did you use if not Df96?

 

[Yezishu]

Pretty decent for zero equipment. What monobath did you use if not Df96?

I bought some pre-packaged chemical powder, and I believe the composition is:
Developer part:
- 4g of sodium sulfite
- 0.3g of metol
- 1.2g of hydroquinone
- 4g of borax (or sodium carbonate?)
Fixer part:
- 6g of anhydrous sodium thiosulfate
- 1.5g of sodium sulfite
Mixed developer part and fixer part together until the final volume is 100ml.

The time spent dissolving actually exceeds the development time, I believe starting with HC110 and Rapid Fix as you mentioned, would be even much quicker. But it's a bit challenging for me to get just 10 ml of HC110 only for one or two attempts, while the pre-packaged kit catches my eye, just 2 dollars.

 

[Donald Qualls]

the pre-packaged kit catches my eye at just 2 dollars.

That's a very attractive price for something that lets you develop literally anywhere (public restroom?) with no equipment. Ilford was selling "sachet" packaging of one-roll, one-shot developer and fixer for a while (not sure if they're still made), but they never interested me because I don't have the one-roll use case, I have a full darkroom. Even so, a good monobath can be a time saver, especially if it's one you can reuse with time adjustment like Df96.

 

[Yezishu]

They never interested me because I don't have the one-roll use case, I have a full darkroom.

They are still selling the Ilford Simplicity Kit and Tetenal Developer Tablets. If security checks aren't an issue, it's also easy to pack some concentrate. While these kits are quite convenient, they still require at least a changing bag and a developing tank, unlike a monobath, which can be used anywhere. "zero equipment" is quite fun to me.

 

[Donald Qualls]

They are still selling the Ilford Simplicity Kit and Tetenal Developer Tablets. If security checks aren't an issue, it's also easy to pack some concentrate. While these kits are quite convenient, they still require at least a changing bag and a developing tank, unlike a monobath, which can be used anywhere. "zero equipment" is quite fun to me.

What I was thinking for those was to mix the developer and fixer (and a suitable amount of something alkaline enough like laundry borax) and have your own monobath with only the little sachets or tablets to carry instead of big bottles of liquid. Obviously some testing would be required to find the right combination of time/temp/agitation...

 

[Yezishu]

What I was thinking for those was to mix the developer and fixer (and a suitable amount of something alkaline enough like laundry borax) and have your own monobath with only the little sachets or tablets to carry instead of big bottles of liquid. Obviously some testing would be required to find the right combination of time/temp/agitation...

So have you tried borax? The original HC-110 monobath formula is already great while borax might be more convenient to pack and carry.
I initially thought my first test roll might be underdeveloped or overdeveloped, but I am lucky enough.

 

[Donald Qualls]

I haven't tried borax, and in fact I just got lucky with the original HC-110 monobath, in that I eyeballed the amount of ammonia needed to offset the acidity of the rapid fixer. Ammonia has some other disadvantages, though; it would probably produce high fog with any other developer than HC-110 or possibly Ilfotec HC.

Another potential option would be crystalline sodium thiosulfate and ammonium chloride, mixed in the correct ratio in place of commercial fixer. That produces a pseudo-rapid fixer that does better on tabular grain films than plain thiosulfate. This could be used with a powder developer -- like D-23 that hasn't been mixed into the water yet. I've even heard that you can buy crystalline ammonium thiofsulfate, though it's apparently so hygroscopic that it's hard to keep it from deliquescing.

 

[Yezishu]

I haven't tried borax, and in fact I just got lucky with the original HC-110 monobath, in that I eyeballed the amount of ammonia needed to offset the acidity of the rapid fixer. Ammonia has some other disadvantages, though; it would probably produce high fog with any other developer than HC-110 or possibly Ilfotec HC.

Another potential option would be crystalline sodium thiosulfate and ammonium chloride, mixed in the correct ratio in place of commercial fixer. That produces a pseudo-rapid fixer that does better on tabular grain films than plain thiosulfate. This could be used with a powder developer -- like D-23 that hasn't been mixed into the water yet. I've even heard that you can buy crystalline ammonium thiofsulfate, though it's apparently so hygroscopic that it's hard to keep it from deliquescing.

Some old books mention that a large amount of potassium bromide can be used with ammonia solutions to prevent fogging during development. HC-110 may already contain enough anti-fogging agents.
I guess that mix a weakly alkaline developer solution with a rapid fixer (containing ammonium thiosulfate) might cause some ammonia to evaporate, resulting in a slower but usable sodium thiosulfate/ammonium thiosulfate fixing mixture, similar to sodium thiosulfate/ammonium chloride. Adding ammonia can not only increase pH but also increase the concentration of ammonium ions, thereby enhancing the fixing speed. As you mentioned, ammonium thiosulfate is difficult to store and is usually sold as a 60% solution or as a concentrate for rapid fixer here.

Ps.a formula based on ammonium thiosulfate, I heard that it can complete development and fixing within 10 seconds, but I haven't tried :
- 6g of sodium sulfite
- 3g of hydroquinone
- 1g of phenidone
- 2.5g of potassium hydroxide
- 12ml of 60% ammonium thiosulfate
- Add water to 100ml.
The use of a large amount of phenidone, high pH, and ammonium thiosulfate together seems reasonable, but it feels like there might be significant ammonia evaporation and not stable.

 

[Donald Qualls]

Ps.a formula based on ammonium thiosulfate, I heard that it can complete development and fixing within 10 seconds, but I haven't tried :
- 6g of sodium sulfite
- 3g of hydroquinone
- 1g of phenidone
- 2.5g of potassium hydroxide
- 12ml of 60% ammonium thiosulfate
- Add water to 100ml.
The use of a large amount of phenidone, high pH, and ammonium thiosulfate together seems reasonable, but it feels like there might be significant ammonia evaporation and not stable.

This, combined with carboxymethylcellulose (gelling agent) and sealed in airtight pods looks like a strong contender for the next reinvention of instant processing.

 

[Don_ih]

This, combined with carboxymethylcellulose (gelling agent) and sealed in airtight pods looks like a strong contender for the next reinvention of instant processing.

We already have the next reinvention of instant processing.

 

[Yezishu]

A monobath for Fomapan 400 based on formulas from Kodak Research Lab and Geoffrey Crawley's Fx 6a, as found in The Darkroom Cookbook (4th edition, page 255).

Water: 750 ml
Sodium sulfite: 50 g
Dimezone S: 4 g
Hydroquinone: 12 g
Sodium thiosulfate, pentahydrate: 70 g
Sodium hydroxide: 4 g
Water to make up to 1 liter

100 ml developer for a single roll of Fomapan 400 (18~20 exposures) in a paper cup. The original Kodak formula only resulted in clear film. Increasing Sodium hydroxide to 10 g, as per Crawley's Fx 6a, can speed develop and produced images but with excessive grain. Finally, I adjusted the Sodium hydroxide back to 4 g and reduced the Sodium thiosulfate to 70 g. A 10-minute monobath process produced some acceptable results (full-frame, Pentax SP). Foma film fixes relatively quickly, which may not align with some older formulas, but adjustments can always be made to compensate the fixing speed.

For two other flims, Lucky 1023 and Kodak 2468, fixing speed needs to be slowed down further.

 

[Donald Qualls]

And that's probably behind the downfall of monobath as a regular item -- it became (in a limited way) popular just about the time film development and fixing times started to diverge. When every PJ was shooting Tri-X, that didn't matter much -- but throw some HP5, some APX 400, some other brand into the mix and the same monobath didn't quite work the same. Even Df96 requires a little adjustment of temperature and/or agitation to get best results from different films.

 

[Horatio]

I'm not satisfied with its performance on Ultrafine Finesse 400, but I've finished the last of that bulk roll. This week I'll try Edu 200 bulk.

 

[Donald Qualls]

Edu 200

I've read that the Fomapan 200 this is (I presume) rebranded from is a hybrid emulsion, partially cubic grain and partially tabular -- that means it may require extra time in the monobath to give full fixing.

 

[Horatio]

I've read that the Fomapan 200 this is (I presume) rebranded from is a hybrid emulsion, partially cubic grain and partially tabular -- that means it may require extra time in the monobath to give full fixing.

Thanks, Donald. I'll take that into consideration.

 

[Yezishu]

Even Df96 requires a little adjustment of temperature and/or agitation to get best results from different films.

Currently, I have an idea to use monobath with Kodak 2468 direct positive flim, so I can get BW slides from a paper cup on the spot. It can't compare to instant film (especially with an ISO of only 0.3~0.8!), but it might be interesting enough.

But 2468 develops slowly and fixes very quickly, possibly due to the very fine silver halide grains. A typical fixer (60g sodium thiosulfate, 3.75g sodium sulfite, 250ml water) with 1:15 dilution clears the film base in less than 5 minutes; 1:30 dilution clears the film base in 10 minutes, while development takes 15~20 minutes. Simple dilution may not be enough to extend the time window. Besides increasing the developer concentration, do you have any other suggestions to slow down the fixing speed?

 

[Donald Qualls]

For Df96 (and presumably for other monobaths) higher temperature accelerates development with little effect on fixing, while increased agitation accelerates fixing with only minor effect on development. Therefore you would seem to want to develop as warm as the film emulsion can take, with as little agitation as won't cause bromide drag. I'd start with 85F and agitation only every third minute for a test roll, then adjust from there when you see the film.

 

[Yezishu]

For Df96 (and presumably for other monobaths) higher temperature accelerates development with little effect on fixing, while increased agitation accelerates fixing with only minor effect on development. Therefore you would seem to want to develop as warm as the film emulsion can take, with as little agitation as won't cause bromide drag. I'd start with 85F and agitation only every third minute for a test roll, then adjust from there when you see the film.

Thank you, I hadn't thought of temperature! In 38 °C, the development time can be reduced from 20 min to just ~3 min, and faster fixing isn't much of an issue. I'm not sure how POTA developer performs at this temperature, but it's worth a try.

 

[Donald Qualls]

Usually developers work much the same at higher temperatures. Developers with hydroquinone may lose activity pretty sharply below about 15C, but ascorbate doesn't exhibit this as far as I'm aware, and metol, phenidone derivatives, and p-aminophenol are pretty linear in their temperature compensation.