March 7, 2010

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

27 comments:

lal:tree said...

Thanks for this. I'm hoping to start making caffenol soon, and this info really helps to clear up the confusion.

Cheers!

Anonymous said...

GOOD INFO,
also the mono-hydrated is the most stable
The one here in NL is the mono; also a pwder but not so white.

imagesfrugales said...

Thank you both for the encouragement and useful additional info. Soada should be stored in an airtight and well closed box and it will be stable regardless of the kind.

Mikeinlagardette said...

This is by far the most useful single piece of information about Caffenol so far Reinhold! It is only possible to buy the "Cristaux" sort in France, so I am off to measure the water content, toute'suite! Many Thanks,
Mike

imagesfrugales said...

Hello Mike, glad to see you here. I'm very courious about your research and hope to see some pics and words from you soon here.

Cheers - Reinhold

kyle said...

Thanks you so much

Unknown said...

Is there any brand or commercial name in Germany ?
I'm trying to localize the components of the recipe and I want to be sure I find the right ones and I think that I will surely find them here in Holland too. By chance any brand they sell in Lidl / Aldi ?

Anonymous said...

About the carbonate. Another source is baking soda (sodium bicarbonate) and lye (sodium hydroxide or caustic soda). Mix one weight part of lye with 2,1 weight parts of baking soda in water, that is exactly the same as using 3,1 weight parts of monohydrated sodium carbonate. The chemical reaction is: NaOH (lye) + CHNaO3 (baking soda) = Na2CO3 + H2O (sodium carbonate + water)

So, when your recipe calls for 54g waterfree sodium carbonate that corresponds to 64,8g monohydrated (1,2x), to be mixed in water, we could just as well use 21g lye and 44g baking soda.

Sodium bicarbonate as baking soda can be found in any supermarket and lye is sold as sewage cleaning or as a strong alkaline cleaning agent to be used before painting things like old furniture. (Do not get strong mixtures of caustic soda on your skin!)

Yet another, slightly expensive way to get sodium carbonate is to fry baking soda in a tough stainless pan, really fry on intense heat. It will steam off carbon dioxide and when all gases are gone you will have sodium carbonate left in the pan, but the pan wont look nice, not the surroundings either if there is no lid on the pan.

-Magnus

imagesfrugales said...

Thank you Magnus,

but these are the 2 methods I would estimate to be most unconveniant and unsafe methods and would prefer to use any other regular developer. F.e. I read several reports that the heating of baking soda lead to blank negatives.

If you are absolutely unable to find washing soda, go to a pool supplier shop and buy pH-Up. It's sodium cabonate. Determine if it is anhydrous or a hydrate and be fine.

Copen-Z said...

"Better coffees like Nescafe, or labeled "mild", "100% arabica", "gold" etc may be not suitable."

are there any special ingredients one should look up for on a can of coffee? because besides nescafe and jacobs, there are no other instant coffee lables available here in my country - other than the ones that smell like baked soya. :)
cheers

imagesfrugales said...

Hi Copen-Z

it turned out that the "better" coffes aren't so bad ;-) Maybe you should increase the amount for 10 to 30 % because they may have some less caffeic acid, but should still work. A friend uses Nescafe Gold without changes in C-C-M and it works. Here these better brands are about 2-3 times more expensive :-(

Using less acidic "better" coffee may result in an increased pH that maybe is compensating. But don't worry about it too much, just do it.

Once you are satisfied with the results, always use the same brand, so you get used to it.

Best - Reinhold

Anonymous said...

I have had good luck making Na2CO3 out of baking soda (generic/private label brand, USA) to get the quantities right. Last batch was 100g NaHCO3 heated on the stovetop until bubbling stopped, which yielded 62g Na2CO3. I added 620ml water to make a 10% solution which seems to work pretty well, I add it to the coffee/vitamin C mix right before development.

imagesfrugales said...

Hi Anonymous (best poster ever :-D ),

converting baking soda by heating is a proven method like drying hydrated soda.

I alway recommend first diluting the soda, then adding the Vit-C, again CO2 bubbles appear. Let the bubbles clear (stir) and only then add the coffee. Might be important, at least you get less foam when adding the coffee.

homeiss said...

Hello. I just put 100g of washing soda in the oven at 180 °C and when it came out it was 89g. So it's kind of a considerable weight difference, but it's not the 20% you mentioned. Should I still treat it as a monohydrate?

Thanks!
Cory

imagesfrugales said...

Hi Cory, no, you should treat it as you tested it: 89 % soda. That's why you did the test ;-)

Oliver said...

Here in Switzerland I found a soda from the company Van Baerle AG. Its sodium carbonate content is 38% (starting from 220 g "Fein Kristal Soda" I heated up and ended with 83 g of fine white powder). So if someone uses this brand, one will have to take times 2.6 the amount of soda crystals; which is 143 g for the Caffenol C M/H recipes.
No wonder my first attempt was totally undeveloped..

imagesfrugales said...

Thank you Oliver for the info. You got almost pure decahydrate.

The soda quality is the winner hands down concerning any Caffenol related problems.

Matthieu said...

Hi Reinhold,

Here in France, we don't get the anhydrous washing soda easily. I only found the “Cristaux de Soude” from the “Saint-Marc” brand at the supermarket (the brand is widely sold here).

It isn’t a white powder, but hydrated crystals (I got a kg for a couple of euros).

I tried to get rid of the water by heating up 100.0g of these crystals to 150°C in the oven. A lot of water came out and I needed 90 minutes heating before it was totally dry. I got 35.3g of very thin, white and dry powder from it. 100/35.3 = 2,83. Assuming I lost a little bit from it when I crushed it (the powder was one solid piece), it is clearly near to the 2,7x factor you told of.

I think that the “Saint-Marc” "Cristaux de Soude" are definitively decahydrate.

Cheers.

Anonymous said...

Hi...very, very nice blog...!
I'm just goin' back to film photography and this seems a very interesting way to develop films.
I've just a (maybe silly) question: Here (in Italy) we have Soda Solvay, that claims to be >99% pure soda (Na2CO3) Is this the right recipe?

http://www.sodasolvay.it/it/product/index.tcm

Thanks,
Donato

imagesfrugales said...

Hello Donato,

please excuse the delay and thank you for your kind words.

I don't speak italian, but if it's a white powder and no crystals then it's the anhydrous/waterfree soda. The formula Na2CO3 is OK.

Happy developing - Reinhold

alancem said...

Hi - your blog and the cookbook have bought fun back to photography!
I am playing with old cameras and different films with varying results. I firmly subscribe to the need for metered exposure and carefully weighed chemicals, but have a conundrum. after failure trying to develop Fuji C200 I wanted to be sure of my soda composition, various packs say decahydrate, some minimum 30%, some 40%. I'm waiting for some pH paper to arrive, but decided to dry an fresh pack. after 6 hours in the oven at 140 degrees C, 1 kilo weighed 1.1 kilo so out of frustration I've put it in a pan on the stove top and heated it to 160 degrees for 30 minutes. It still weighs 1.1 kilos. Help

As an aside, has anyone tried developing Konica IR film? I have three rolls just tempting me....

imagesfrugales said...

alancem said: I wanted to be sure of my soda composition, various packs say decahydrate, some minimum 30%, some 40%

Hm, minmum 30 % means it it not pure washing soda, something else is added. Maybe a bleaching agent or a filler or whatever. These mixes are not suitable at all. Be sure to get pure washing soda, hydrate or not, but nothing else. Then you can check for water content. You don't need to dry a whole kilogramm for hours, do it with 10 gramms and weigh before and after and you know wht you have in hands. The dried soda must be a white powder. If it's not a white powder, it's wrong. After that you can recalculate the needed amount for your hydrate. Be sure to do the math right.

The Konica IR is a color film? If so, I wouldn't sacrifice it in a bw-developer. That's like drinking a vintage malt whisky on the rocks.

alancem said...

I'll start again with the soda, I've had some good results with Fomapan 100 and 400, but disappointing with FP4 (admittedly dated 1999). Then I had a series of outdated film Technical Pan, Fuji c200, Ilford XP come out totally blank (not even any edge marking) or so dense it will not scan.

Ralph Lundvall said...

I bought this from Amazon. http://www.amazon.com/gp/product/B00B08IUAS/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1

Free shipping.
I baked 10g @ 275F (135C) for one hour. Result was 10g using an accurate gram scale.
When the C powder shows up, I can post results.

imagesfrugales said...

Hi Ralph, there's no need to post results here, this is not a forum or discussion board, but thank you very much for your interest. Feel free to post your images on the caffenol groups at flickr or ipernity or .....

Your washing soda is quite expensive compared with the one I can get here (500g, 1 Eur in the supermarket), but it depends of course on your local situation. Arm & Hammer e.g. is a good soda (8 % water) available in supermarkets in the USA. And obviously yours is 100% waterfree.

Unknown said...

I've just purchased some 'soda crystals' and have put 50grams in the oven at 150 degrees Celsius. After ten minutes I took a look and the powder had liquified. Does this mean I have a decahydrate? It still weighs 50grams, but I wasn't expecting it to turn to liquid!

imagesfrugales said...

Hi Mr. Unknown, I never heard of that phenomenon, sorry.