June 17, 2010

Reducing pH for highspeed films? Fomapan 400

I decided to delete the recipe, since Caffenol-C-L is much better.

PS: I also deleted the recipe because my notes about it were not correct, as I said here before. Restoring impossible. That was never a reliable recipe. So save any angry comments. Sorry for any unconveniance. I don't follow this path any further. But general thought here still might be of interest.
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Some people suggest reducing  the pH to reduce fog and grain. Borax is suggested as a mild alkaline. My first trials with borax were not encouraging, but why not reduce the soda? So I made a somehow "lighter" Caffenol-C-M, hoping to tame the developer with highspeed films. No scientific approach at all. I took a Fomapan 400 as 120 film, loaded my 65 years old Bessa 66 and shot the roll without metering the exposure. To be honest, I forgot my meter at home. All 12 images were nicely usable, though about 1/2 was overexposed. I estimated for 400 ASA, maybe the Fomapan 400 should be rated higher. OK, only one film, and my first Fomapan400 in Caffenol.

This pimped Caffenol-C-M contains 1/2 of the Vit-C and much less soda, but the same amount of instant coffee as before. pH is 9.2 instead of 9.7 before.  If we go below a certain pH, development will probably stop completely. This point I still have to examin. For low pH-Caffenol it is more important to measure the soda exactly and use the right one, be it anhydrous or hydrate with recalculated amounts - see "soda-myth-and thruth"-post.  Because the lower the pH, the smaller the different amounts of soda to make big changes. I hope you got a weightscale in the meanwhile ;-)

Results: low fog level, grainy but "nice" grain, sharp, wide tonal range, probably more than boxspeed.


Click on the images to enlarge as usual. Crop is 10x10 mm neg size. 3 more images on Flickr.

Have fun with coffee - Reinhold

10 comments:

Anonymous said...

Perfect timing! I've been meaning to try your Caffenol recipes for a while now, and have been wondering about the 10-pack of 120 film I just bought... Fomapan 400, precisely! I'll try it out tonight.

Thank you for sharing your experiments. Keep up the great work!

Mikeinlagardette said...

Reinhold,
how very interesting! I have also been gradually reducing the sodium carbonate content when using Fomapan 200, and the best results were with a very similar mix, viz. Coffee 20g, washing soda crystals 15g, ascorbic acid 6g, water to 500ml. There was a significant reduction in grain, and an apparent improvement in definition, although neither of these parameters has been tested scientifically! I don't usually bother with a light meter for outdoor photos, but perhaps with more careful exposure control, it may be possible to also reduce the development time a little. Great fun, and thanks again for your stimulating work.
Kind Regards, Mike

imagesfrugales said...

Hi Mike,

it's great to read about your activities. I guess your mix will have a similar low pH like mine (9.2). That seems the most rewarding direction for further modifications, to see how low we can go. C-C-M has already a quite low pH compared to f.e. the digitaltruth recipe (pH 10.4, if I remember right). Exciting "development".

Thanks and best wishes - Reinhold

Anonymous said...

I have been looking into some old german recipes, from Foto-Schule Hamburg. They had a recipe based on stand bottles (getrennten lösungen), mixing A B C and D according to film or paper type I will need a hope for the translation in a PDF-file shortly).

I was wondering how OUR ingredients wold measure up here : Soda indefinitely, coffe too probably, but whatabout Vitamine C?

3 mixes :

1000 ml with 162 gram soda added, in a closed bottle.
1000 ml with 48 gram vitamine c added, in a closed bottle
1000 ml with 120 gram coffe added, in a closed bottle.

To use mix one part of each to reach the volume needed in the tank:

100ml A B and C for one 35mm film in my Paterson tank.

This way I could just load the film in thwe tank, mix 3 liquids and be done in a few minutes, instead of lengthy chemical mixing.....

Have you given this a thought?

ErikP

imagesfrugales said...

Hi Eric,

one of the biggest advantages of mixing Caffenol(C) right before development is that you have always the freshest developer you can imagine. Since there are no preservatives at all in the mix, I don't think that it is a good idea to keep them in premixes. Especially half filled bottles may be risky. Why give up the advantage of beeing 100% sure to have a fresh and working developer with 100% reproducible results?

What I do, is to make a premix of only the soda in a 5 litre canister. That is for sure no problem.

And don't forget the mixing order. First the soda, then add Vit-C to form the ascorbate, indicated by CO2 gas bubbles. You should wait 2 or 3 minutes before adding the coffee.

Anonymous said...

Too bad you deleted the recipe! I think experiments should be encouraged, Reinhold.

Lots of people should be encouraged to experiment more on one hand, but told to WEIGH and MEASURE exactly on the other.

What people are doing is experimenting with no real base to work from, since they have no clue about the concentration of their mix, they experiment blind, without realizing it!

As to the PH-problem using Natrium sulfit, or Kalium matabisulfit as a buffer chemical might solve that problem, probaly less than 10 gram per litre should work wonders....

Erik

Anonymous said...

Preservatives :
Soda will last indefinitely in water solution.
Vitamin C IS a preservative in its own right and should last.
Cofee probably needs to be bolstered with 10% Natriun sulfit - but maybe not, I'm not 100% sure here, since we're after the cafeine acid, and maybe storing it in a bottle in water solution would give us more of that?? :))
ErikP

imagesfrugales said...

Thank you Eric(P) for the suggestions. Of course all the agents used in commercial developers like sulfit or bisulfit can be tried, probably with good results. But up to now I want to keep things as simple as possible, and I found some faults in my notes of the low-pH-recipe, so I decided to delete it. I also want to experiment further with Borax, although the first trials were not satisfying. If you want to experiment with low-pH-Caffenol, it's pretty simple, but you MUST have a pH-meter, everything else is a blindfolded flight in the night. In the last couple of weeks I didn't have enough spare time for playing around and I was a bit annoyed by experimenting. I had to test new gear (f.e. the fabulous 2.8/180 CZJ-Sonnar for my P6)and I wanted to take some "real" images. There will be more Caffenol playing in the future, but not as quick as you may want.

Best regards - Reinhold

Anonymous said...

I have tried out this idea by now, making 1 liter bottles of each separate ingredient, at 3 times the concentration.

For use I just measure out 200ml from each bottle, to make 600 ml for the full tank. Add 15ml of 10% KBr. The film comes out great, even if I have left the concentrated bottles stand for several weeks (a total of 3 liter mixed developer don't last me long!).

Interesting observation :
The concentrated Soda is a little turbid (a little grey looking. The Vitamine C concentrate is totally clear.

Mixing the two instantly lowers concentration of both, the soda clears amd then the mix turns a light yellow-green, this is presumably from the reaction, turning ascorbic acid into sodium ascorbate.

Then I add the 10% concentrate of KBr (25gram in 250ml water) just 15ml of it, and finish off with 200ml coffe concentrate (this is REALLY black and smelly!) Another reaction occurs, but not as powerful as when mixing the chemicals straight from the boxes, and the developer turns out less smelly too.

Since I put the concentrate bottles into the kitchen well before mixing, all the temperaturea are already "right" no worries over high temperatures in the soda mix, no worries over wether the coffe did dissolve, and better yet, in the coffe, heavy un-dissolvable stuyff that would contaminate the film settle on the bottom of the bottle!

I think more should give this a spin and report wether there are problems with film/developer combinations, its sure a very fast way to start working, once the preparations are done.

ErikP

imagesfrugales said...

Thank you very much, Eric, for this usefull info.
Best regards - Reinhold