Soda: myth and truth

Sometimes I get messages about not successful Caffenol developments. It almost always turns out that the used ingredients are not suitable! "Better" coffees like Nescafe, or labeled "mild", "100% arabica", "gold" etc may be not suitable. But most confusion is about soda. In some countries it seems to be difficult to get the waterfree one. How can you determine which kind of soda you got?

First of all, waterfree soda is provided as a white powder. If you have small crystals, it will be either the monohydrate or decahydrate. Take an amount of your soda, determine the weight and put it in the oven above 120 °C. If it looses weight after some time, you have a hydrate. I tested my waterfree soda and it only looses about 2 or 3 gramms of 100 gramms, neglectible. If you loose about 20 %, it's the monohydrate. If you loose more than 50 % of weight, it's the decahydrate. Above 34 °C the decahydrate turns to monohydrate, above 107 °C the monohydrate turns to waterfree soda. When you don't loose weight anymore, all the water has evaporated and you now have pure waterfree soda. It might take hours, I have no clue how long.

Once determined which kind of soda you have, you can also use the mono- or decahydrate. Take 1.2x the weight (!) for mono- and 2.7x the weight (!) for decahydrate. Volumetric measuring is not possible, I don't know the specific densities and the scientific determined densities are not usable because they don't regard the huge amounts of air between the crystals/powdergrains.

So you can use the other kinds of soda than the waterfree, anhydrous one, but it makes things complicated. Btw, if you have a pH-meter, the final mix must have a pH of about 9.7. Using the wrong soda or miscalculating will result in a lower pH and reduces the developers activity dramtically.

References:

http://www.seilnacht.com/Chemie/ch_naco.htm
http://en.wikipedia.org/wiki/Sodium_carbonate

The image was shot on TMax100 35 mm film @ about 800 ASA without any change of the process. The negs are quite thin and you have to do some adjustments during and after scanning, but it works - not too bad as you can see ;-)

Important note for recipes: when I say "XYZ" I mean "XYZ" and not "ABC".

Cheers - Reinhold

Caffenol-C-M details

1. picture: Fomapan100, EI 400, whole image
2. picture: EI 400, crop 10x10 mm negative size
3. picture: EI 100, crop 10x10 mm negative size
4. picture: TMax100, EI 200, crop 10x10mm negative size

Click on the images for bigger size.

All images developed in Caffenol-C-M as described in former post. On my desktop screen, the 10x10mm crops represent whole images of 1.30x1.30 meters print size for 120 film and still 50x80 cm for 35mm film! Caffenol-C-M enhances film speed without changing anything. Compare the EI 100 and EI400 images, both from the same roll, there is almost no loss. Just a tiny little bit more grain.

The last image is a 10x10 mm crop from the TMax100 exposed at EI 200 ASA. Almost no grain, extraordinary rendering from highlights to shadows, usable exposure range from 25 to 800 ASA. The subject had a contrast range of 9 stops. All in all this combo can handle a contrast range of 13 - 14 stops! And you need an extremely good lens to scratch the resolution limits. That's what I call "state -of-the-art".

Images 1-3 made by a 65 years old Voigtländer Bessa 66 with uncoated 3.5/75 Skopar, image 4 made by Pentacon Six with 2.8/80 Carl-Zeiss-Jena Biometar and z-ring.

Stay tuned. More to come ...... Reinhold

Caffenol-C-M, recipe

Hi there,

so lets start the show with my basic recipe and some words about the ingredients. You already know that Caffenol-C is made of instant coffee, washing soda and vitamin-C.

All recipes are based upon 1 litre solution, measured in gramms and milliliter (ml, 1/1000 of 1 litre). No teaspoons allowed here! No ounces, inches, quarters, barrels, °F etc. I only use international standard units. In many households you will find small measuring mugs f.e. for doing the laundry. These will be usable if they have scales. A weight scale will be of course a bit better, but is not neccessary.

UPDATE: You can use volumetric measuring with Caffenol-C-M, but NOT with Cafenol-C-L, that will be introduced later. Using a scale is HIGHLY recommended for every recipe.

If you live in a country using not international standard units, you have to calculate the amounts yourself. Sorry! Now here we go:

Instant coffee: granulate (crystals) with lot of air included. Buy the cheapest brand you can get. More expensive ones might not be so good. Get the "strong" labeled version if possible. Not the "mild" ones. The active substance in coffee is caffeic acid, that behaves similar to pyrogallol and is a very compensating developing agent. I tried some cheapest brands here in Germany from Aldi, Lidl and other supermarkets. They all taste the same (awfully) and I guess they are all made by the same company or at least the same method. So it shouldn't be a problem to get reproducible results. 200 gramms for 3 Euro.

Vitamin-C: ascorbic acid, the second active developing agent. Works similar like Hydrochinone, giving more contrast and is hyperadditive to caffeic acid. Also reduces fog and of course developing time. Whenever possible, buy pure Vitamin-C, small crystals. Here I buy 100 gramms for 2-3 Euro, available in any pharmacy. Don't use vitamin pills or tablets, there will be other substances added and you might have to adjust the recipe. Buy only pure crystals for reproducible results. Used also in a famous commercial developer.

Washing soda: sodium carbonate (Na2CO3), waterfree (anhydrous). Be sure to get the waterfree one, white powder. If you should have crystals, it is not waterfree and I do not recommend it. You need much more and depending on the kind of hydrate you must recalculate differently. Soda is used for making the solution alkaline, that is important for activating the developing agents. Available at drugstores, supermarkets, zoo shops, swimming pool suppliers. Here at drugstores less than 1 Euro/500 gramms.

Recipe for 1 litre Caffenol-C-M, means for medium fast 100 ASA films (adjust yourself for other quantities)

1. 1 litre water
2. 100 ml washing-soda or 54 gramms
3. 16 ml vitamin-C or 16 gramms
4. 160 ml coffee or 40 gramms

Dissolve one after the other in the given order. Wait until each agent is dissolved completely. Stir while adding, especially the soda should be added slowly for good solution. I use tap water, no probs so far. The dissolving of the soda will heat the solution for about 3 °C. Keep that in mind for a proper temperature. Little fogging of the solution caused by the soda was no prob so far. When adding the vitamin-C small bubbles will appear, wait until they have cleared before finally adding the coffee. This is important! Then add the coffee, stir well and let stand the soup for about 5 minutes. The coffee needs some time to dissolve perfectly. Do not store, use within 1/2 an hour.

Develop for 15 minutes at 20 °C. Agitation first 30 seconds, then 3 times each minute. Intermediate rinse or stop bath, fix and rinse as usual. Tested with TMax100 and Fomapan100 so far. Other 100 ASA films may need slight adjustments. Not recommended for ASA 400 films or faster.

1 litre will cost about 1 to 1.20 Euro. Of course you will need less for developing 1 film, so depending from film and tank size, 1 development will cost about 30 to 60 Euro-Cents. Rodinal stand development will be much less expensive, but Caffenol-C competes well with commercial developers and the results are outstanding. No joke!

Image info: Pentacon Six with 2.8/80 Biometar and z-ring, KodakTmax100, exposed at exposure index EI 200 ASA, Caffenol-C-M. The image from the first "Hello"-post was made with Fomapan100 at EI 100 and the same soup, time, temperature.

More details and sample pics for Caffenol-C-M with the next post.

Important note for recipes: when I say "XYZ" I mean "XYZ" and not "ABC".

Now I need a cup of coffee.

Cheers - Reinhold

Hello

Hi there,

this blog will be dedicated to a wonderful film developer you can mix yourself at home with ingredients you can buy in almost any supermarket, drugstore or pharmacy. It's names are "Caffenol" and "Caffenol-C".

Added Vitamin-C improves the quality in such a degree that it rivals the best commercial developers. The posted image was made with a 65 years old camera called Voigtländer Bessa 66, it has a beautiful uncoated 4-element lens named Skopar (3.5/75), exposed on Fomapan 100 film (type 120) and developed in Caffenol-C. Details like recipe and other tech stuff later.

More to come .... Reinhold