Saturday, May 3, 2014

Is Caffenol a good option as film developer or is it just a curiosity?

Most people begin using Caffenol just to see if it works. And the most spread recipe for Caffenol is the one reproduced in the site of Digital Truth from which I made Copy & Paste here.


Caffenol film developer

Water8fl oz
Arm & Hammer Washing Soda2tsp
Folger's Coffee Crystals (not decaf)4tsp
Mixing Instructions: Mix soda until completely dissolved and solution is clear. Add coffee, mix until all grittiness is gone and solution is uniform. Let stand 5-10 minutes until microbubbles clear. Use within 30 minutes.
Dilution: Use undiluted.
Usage: 30 mins.
Notes: Gives imagewise stain and general (fog) stain. All teaspoon measures should be level, or slightly rounded for coffee crystals.
Everybody that tried this recipe comes to the conclusion that OK, it works, the film is developed in 30 minutes but it is a dirty developer, the film remains foggy and stained and with hudge grain. For playing with it is OK but to have decent developed films, better another choice. There have been several contributes to turn Caffenol a decent developer, mainly from Reinhold who proposed several recipes of Caffenol combined with Vitamine C or, better said, with sodium ascorbate.

Recently, at Flickr, somebody started complaining about caffenol and he (or she) was going to give up using Caffenol for the reasons I said before: stain, fog, grain.

I started then to test several possibilities, under my opinion that a developer must be as simple as possible and with the minimum amount of chemicals. Using stripes of film, I made a solution of coffee and start increasing the amount of alkali, at that time I used Sodium Hydroxide, until I was sure that some development would happen. I exposed then cheap films like Polypan F and Shangai GP3 and the results were more than satisfying. I can say now that coffee is an excellent developer, at least for the films used.

The recipe of Digital Truth given above is a bad recipe. On the other hand the quantities measured in spoons may work differently for different people.

The recipe I use now is like this and I am calling it Caffenol Black or Caffenol Solo:

500 ml of water
20 g of soluble coffee
5 g of Sodium Carbonate*
Water to make 1 liter

First dissolve the coffee in water and then add the alkali. The order is coffee-alkali and not like the recipe of Digital Truth says. It works much better. Sodium Carbonate can be added as solution, if you dissolve 100g in 1000 ml, use 50ml of this solution that may be kept for other Caffenol batches.

The Caffenol should be used just after preparation and it takes some 60 minutes (and not 30 minutes) to develop your film without stain, without fog and with very acceptable grain.

* Important notice: after discusssing this with Reinhold, who had bad results with the recipe above (underdevelopment, no shadow details), the 5g/l are not a must, Important is to achieve the right pH that is about 10,4 to 10,6, according to my cheap pH-meter. Different coffees have different acidic properties and may need more or less alkali. I even have used Sodium Hydroxid, adding it drop by drop until I reach pH 10,4 and it worked.


Robert W. said...

RE: Important Notice
Henrique, you should be able to make a buffer to add to the formula (based on it working on the alkali coffee you find (or place a generous amount of buffer solution so it doesn't matter). Then you can be assured that your pH is the same every time, for every coffee. That would take pH variance out of the equation. Here are some photographic buffer chemical pairs from Roger's book.
Rogers The Chemistry of Photography 2007 0-85404-273-3
5. Processing Solutions

Buffer combination pH Range

K2SO3 K2S2O5 6.5-8.0 Potassium Sulfite - Potassium Metabisulfite
Na2SO3 Na2S2O5 6.5-8.0 Sodium Sulfite - Sodium Metabisulfite
Na2B4O7 B(OH)3 8.0-9.2 Sodium Borate - Boric Acid??not sure I wrote correct
Na2CO3 NaHCO3 8.0-11.0 Sodium Carbonate - Sodium Bicarbonate
Na2B4O7 NaOH 9.2-11.0 Sodium Borate - Sodium Hydroxide
KBO2 KOH 11.0-12.0 Potassium Metaborate - Potassium Hydroxide [Potassium Metaborate]
NaB02 NaOH 11.0-12.0 Sodium Metaborate - Sodium Hydroxide [Kodak "Kodalk" Balanced Alkali]
Na3PO4 NaOH 12.0-13.0 Sodium Phosphate (TSP) - Sodium Hydroxide

**1% solution of TSP is pH 12

H. Sousa said...

Thank you for your comment. A very good tip, indeed and I already tried the pair Sodium Carbonate-Sodium bicarbonate and I could publish another version that may be reused, perhaps. A little metabissulfite...

But to respect the simplicity of the original recipe, 4tsp coffee, 2 tsp soda in Digitaltruth, I took the risk of leaving bicarbonate out this time. And I think that the important are not the 5 g soda, it may change according to coffee (and water) but there will be an optimum that may reach 6 or 7g/liter. The pH of 10,4 should be searched. It may decrease during development but this is also an advantage, it will not overdevelope.
Someone told me that it needed 14 g of soda to reach 10,4 pH, but the result was the same as several that use Caffenol once for curiosity and give up because it stains and fogs and give hudge grain. This friend must check its pH-meter, it is impossible to have 14g soda and only 10,4 pH.

knutsandvik said...

I tried your recipe with better result than standard Caffenol, but I got Brbomide drag instead. Any tips?

Henrique Sousa said...

Why bromide drag? The recipe for Caffenol Black is just coffee and soda. I am using now 20g coffee, 6g soda and 4g table salt as anti fog stuff.

Henrique Sousa said...

Because salt is also a restrainer, the developing time must be extended to 90 min.

Henrique Sousa said...

Could you show these bromide drags? Did you try to refix? They may not be bromide drags. If they are, more agitation is needed.