Caffenol LC -- a low contrast developer for document films

I've just finished scanning a roll of Kodak Imagelink HQ shot at EI 50

in a Minolta 16 camera, developed in what I call Caffenol LC.

Gradation is excellent, though I don't think the toe speed is actually

50 (OTOH, with reduced agitation and longer development I expect it

will get there). This film is much like Tech Pan -- it's a high

contrast microfilm stock, normal pictorial EI of 25 with low contrast

developers like POTA or Technidol, and EI 50 with TD-3; I've

previously developed it for EI 50 in HC-110 Dilution G with good

results, but less sharpness than I wanted.

 

This time, based on my reading in Anchell & Troop, I reduced the

amount of coffee by half relative to standard Caffenol, while keeping

the sodium carbonate constant. In a 60 ml batch for the small

capacity tank I made for Minolta 16 films, that came to 1/2 tsp of

each ingredient. I gave twenty minutes at 71 F (room temperature)

with five slow inversions, about fifteen seconds, every two minutes

after constant inversion the first minute. Four changes of water, ten

inversions each, served as stop bath, followed by three minutes in

Ilford Rapid Fixer and an Ilford water conserving wash.

 

Results are excellent; there is almost no general stain (as is found

on conventional films in Caffenol), and though the images look thin

(as they always do on the crystal clear microfilm base), there is good

shadow detail, excellent gradation, and a good range (about like what

I'd expect with a one stop push on Tri-X); in addition, sharpness

appears significantly improved over the HC-110 I've used previously,

while grain is still too small to show at my 2400 ppi optical scanning

limit; with this film, even in an accutance type developer, grain

shouldn't be an issue up to around 8x10 from a 10x14 mm negative.

 

There were thin spots on the first few negatives in the roll, that I

believe were due to tiny air bubbles that didn't get dislodged in the

initial agitation; only the first three frames are affected, so it's

not a general chemistry related problem. My suspicion is that I

didn't let the developer sit long enough to clear microbubbles

incorporated from the coffee and carbonate granules during mixing;

next time, I'll let the mixed developer stand for ten minutes after

mixing is completed.

 

Next roll, I'll increase the carbonate by 50%, to get closer to the

low contrast formulae in Anchell & Troop, and presumably shorten

developing time with the increase in alkalinity. I'll also reduce

agitation, going to three or even five minute cycles to increase

compensation and allow the shadows to come up more without blocking

highlights; that should get me to a true speed of EI 50.

 

Soon, I'll try the same thing with Copex Rapid at EI 100; if it works

well, this developer is a little cheaper than homebrewed H&W Control,

and a lot cheaper than SPUR developers or Bluefire HR, as well as

being much more accessible. It's also a great deal cheaper than

Technidol, and should work as well on Tech Pan as it does on Imagelink HQ.<div></div>

Oh, hell -- that was f/5.6 at 1/50, not at 1/200.

>Oh, hell -- that was f/5.6 at 1/50, not at 1/200.

 

You sure you ain't been taste testing the stuff too? }:^)>

Well, not with the sodium carbonate in it, no...

 

...but I do consume 2-3 double lattes on a weekend day, and 4-5 cups of brewed coffee and a double latte on weekdays...

 

Still the best use I've found for instant coffee, though; the stuff certainly isn't for drinking!

I've just developed a film with "Caffenol LC".

Great idea.

 

Pictures look good, allmost no stain.

Looking at the negatives I have only reached an EI of ASA12 (ASA 25 looks too thin) but I will try a stronger brew and longer times the next days.

Try printing before you judge the negatives -- microfilm base is clear, and it makes the negatives look thin when in fact they have normal contrast, because your eye is so accustomed to the gray base of 120 and (more so) 35 mm film. Further, if you're using a 16 mm camera, it's hard (even with a loupe) to see the shadow detail that will tell you the real speed -- I've had good results holding the negatives in midair with a strong light (bare bulb or the sun) behind, and looking for scatter in what appears to be clear areas; it looks like miniature glitter in the film.

 

In any case, for microfilm, I'd tend to extend development with reduced agitation (even all the way to stand development, though I haven't tried that with Caffenol LC yet) before using a stronger brew -- 30 minutes in regular Caffenol (twice as much coffee as the LC version) with agitation 15 seconds per minute gives a normal negative on Tri-X (albeit with a brown general stain); that would give document contrast with microfilm stock.

 

Of course, there are also different microfilm stocks; there may be emulsions slower than Imagelink HQ and Agfa Copex, though I'm not familiar with them. I know some people do wind up rating Imagelink HQ and Tech Pan at EI 12 -- if I have to do that, I may as well get some tape and make it into a blue/black ribbon chain for the Christmas tree, because it's useless to me in a Minolta 16 at that speed. It's hard enough to get useful DOF and hold the camera steady at EI 50 (which was the rating on the image posted above; EI 100 would have gotten me f/4 at 1/200, and probably sharpened up the car and driver a good bit).

Thanks for you quick response,

 

the film I used was Imagelink HQ (Estar Base) in 16mm, shot in a Edixa 16. I've did exposures with ASA 6, 12, 25 and 50. The ASA 50 pictures have almost nothing on it (only a few black spots where the brightest parts have been). On the ASA 25 pictures I can see almost every detail, although very very thin. ASA 12 seems ok. Thin but everything on it.

ASA 6 looks like the negatives on FP4+ (too dark).

 

I will do prints when I find the time. I think the best image would be one between the ASA 25 and the ASA 12.

 

I will try longer development vs. more coffee (instant coffee varies in strength significantly).

<i>(instant coffee varies in strength significantly).</i><p>

 

That might be the issue, in fact; not only does instant coffee vary in strength, but in content due to different methods of getting from roasted beans to powder. The original recipe for Caffenol called for "coffee crystals" which would suggest the Folger's brand, and the person who posted it here (IIRC) used that brand. I used Fred Meyer store brand (it's a chain in the Northwestern US), which is a very good copy of Folgers, down to the same shape jar (though in glass instead of plastic). These are made, AFAIK, by the cold spray method, like powdered milk. If you used another type of instant, you might get different results because the developing agent might suffer from other methods of making the coffee into instant.<p>

 

Maxim freeze-dried would be the other type I'd expect to work well, because it's made without heat after initial brewing, but the old style powdered coffee might be inferior; some brands are dehydrated by heat instead of vacuum sublimation or cold spray, and the prolonged high heat needed to drive off the water may partially destroy the developing agent (which, based on the original thread, is most likely caffeic acid). Typically, these are also the brands that taste worst, and smell least like good brewed coffee -- and the cheapest.

As I'm living in Germany it'll be almost impossible to use the brands you mentioned. So I'm stuck to testing. I was surprised how well the pictures came out, far better than my first tests with Rodinal 1:250 and Imagelink HQ. But first I'll have to order new Soda, my stock will only last for about 3 more films.

I use washing soda I got at the supermarket -- it's sold as a detergent aid, right alongside the borax. I assume it's monohydrate, because both anhydrous and tetrahydrate tend to become monohydrate after storage and this is sold in paperboard boxes that aren't vapor tight.

 

For coffee, if you look for a variety that comes in clumps with some glossy crystalline surfaces you should have the correct type. I'm not familiar with what's sold in Germany, but if all else fails, you should be able to brew to the correct strength with 3 tablespoons (about 45 cc volume) of drip grind coffee to 240 ml of water; heat the water to 95 C, stir in the coffee, and let stand until cold, then filter to remove the grounds. More work than instant, though. Liquid instant should also work, at three times drinking strength for Caffenol, or 1.5 times for Caffenol LC.

When I bought my last batch I just walked to the supermarket and bought a box. Unfortunately it becomes hard to get pure soda (you can get a lot of stuff with "real washing soda" in it, but the real stuff? No way).

 

So the only option would be the local pharmacist but he bills 5Eur/100g. So I looked and found a mailorder-company and as I also need some other things (like acid for sw-slide-bleach and so on) it's ok.

 

You say you use the monohydrate. As the chemical description varies between german and english I have to ask:

I have the option between

 

"Natriumcarbonat cristal Decahydrat (Na2Co3+10H2O)"

and "Natriumcarbonat wasserfrei (water-free?) aka. heavy Soda"

 

 

Which one do you recommend? The last is about half the price of the decahydrat but according some old photo book 100g decahytrat equals 37g wasserfrei? I'm a bit confused.

 

Thanks.

Wasserfrei = Anhydrous, or no water into it

Dekahydrat means that 10 molecules of water are bound to each of carbonate.

 

If you have 1 mol of anhydrous (106 g), add 10 mols of water (180g) and you have 387 g/mol

So 100g (dekahydrat) *106/387 = 27.4 g wasserfrei

 

If wasserfrei is cheaper you are getting a better deal, buy that one.

I agree, the wasserfrei (anhydrous) is preferred; it dissolves more readily than decahydrate and you just need to use a little less of it than the monohydrate to get the same alkalinity (I don't recall the conversion, but Patrick Gainer gave it in one of the other Caffenol threads -- look for one in "Uncategorized" from 4/23, I think that's the one). I also don't know how many grams there are in a teaspoon of either coffee crystals or washing soda -- and my good scale is still packed, somewhere; the one I use for my diet only reads to the nearest 5 grams. It should be easy to work out the conversion from monohydrate to anhydrous, though -- the monohydrate weighs 34 grams more per mole (the weight of the water of hydration), and you need the same number of moles in either case.

 

You can't convert by volume, at least not readily; the wasserfrei is called "heavy soda" because it's denser than monohydrate or decahydrate (the water takes up more space than it adds in mass).

Oops, Pablo had it right -- Oxygen is element 8, atomic weight 16, not element 16 with atomic weight 32, so each water is 18 daltons, not 34.

Christian, something else occurred to me late last night -- you might want to check the instant coffee you're using to be sure it's all coffee. I'm pretty sure chicory (a root commonly used in coffee by the French and in the New Orleans area of the United States) has no caffeic acid, and if your German instant is adulterated with roasted grain (which is sold, with no coffee content, as a coffee substitute in the United States under the name Postum, and which was used as "ersatz" coffee in Germany during the Second World War due to shortages), the grain product certainly has no caffeic acid.

 

So it might be that you just need to find a brand of instant coffee that's all coffee -- or the stuff I said earlier about cold dehydration may enter into it as well.

Christian, talked to a friend of mine that lives near Wurzburg this morning.

While we were on the conversation I brought th coffee topic up.

He said he buys good qality coffee at affordable prices @ALDI

Look for the "premium" coffee

The coffee I use is from Lidl (Lidl is a supermarket-chain like Aldi).

It's called "Granarom Gold Supreme Quality Coffee, 100% Arabica) if it would contain anything other than coffee it must be declared.

 

As Donald pointed out in rec.photo.darkroom the coffee he used contains only as much arabica as needed, rest is robusta, which may contain more acid than pure arabica.

 

While talking about coffenic acid - does anyone here know how much of it is contained in instant coffee?

<i>While talking about coffenic acid - does anyone here know how much of it is contained in instant coffee?</i><p>

 

From <a href="http://www.coffeescience.org/other.html">here</a> I get the following:<p>

 

<i>Chlorogenic acid is the most prominent polyphenol in coffee, though there are others. Robusta coffee can contain up to 7-10% chlorogenic acid, where the concentration in Arabica coffee is slightly less at 5-7%. That means a cup of coffee can contain anywhere from 15 to 325 milligrams of chlorogenic acid, depending on the composition and method of preparation.</i><p>

 

Chlorgenic acid is the glycoside precursor of caffeic acid, converted by drying and roasting the beans; from this, I would expect that in the same roast, robusta might contain anywhere from the same to as much as twice caffeic acid as arabica. But it appears that chlorogenic acid itself is also present in amounts comparable to caffeine (typically 200+ mg per serving), and the original Caffenol thread suggested chlorogenic acid should be about as good a developer as caffeic acid.<p>

 

How instant compares to brewed from grounds, or how different instants compare (relative to chlorogenic and caffeic acid), is probably unknown and/or a trade secret of one or more entities. Generally, however, one would expect robusta coffees to contain more caffeic and chlorogenic acid -- so you might just need to increase your proportion of instant coffee with your "too good" 100% arabica variety.

Are you just looking for a low contrast developer for high contrast film?

 

You could look at LC-1.

 

http://members.aol.com/fotodave/Articles/LC-1.html

 

It's designed to get normal contrast out of real high contract film.

<i>You could look at LC-1</i><p>

 

That's a standard low contrast developer, along the lines of the general formula in Anchell & Troop. The point with Caffenol LC is that it's non-toxic and doesn't require access to a photographic chemical supplier, but costs like a common economical developer such as HC-110 (well under a half dollar for a 35 mm roll); there's also the novelty of getting good pictorial range and excellent speed from coffee...

I quickly ran the calculator and I think I came up with around 50 cents for 3+litres of developer. Assuming I didn't drop a decimal place or something that's not too expensive. Only the metol and hydroquine would need to be gotten from a photo chemical supplier. Even then I guess you could swap in Vit C for the hydroquine if you adjust the pH.

I've just developed a new roll and I think I overdid it a bit *G*.

I increased the amount of coffee about 20% and extendet the time to 30mins with 15sec every 3 mins. The roll was exposed like the last ASA 6, 12, 25 and 50. Even the ASA 50 frames are a bit dark. So my next try will be only 10% more coffe and 30mins what should result in EI 50 at resonable contrast.

 

@Robert:

Of course I could go and buy me a bottle of LC-1 or Neofin Doku or SPUR Dokuspeed or whatever. But where's the fun in this?

<i>The roll was exposed like the last ASA 6, 12, 25 and 50. Even the ASA 50 frames are a bit dark. So my next try will be only 10% more coffe and 30mins what should result in EI 50 at resonable contrast.</i><p>

 

Dark, or too contrasty? Shadows overly dark, too? Then overexposed -- meaning you got more than EI 50 from the film, which is pretty darned good for film commonly rated at EI 12 to 25. If too contrasty, then you have the right idea, either cut the developer, cut the time, or cut the agitation some more. Thirty minutes, agitation every 5 minutes is my next step -- hoping to get EI 100 from Copex Rapid.<p>

 

Remember, reducing agitation cuts contrast without reducing development of shadows, preserving film speed; shortening process time or reducing the developer concentration reduce development for shadows as well as highlights, reducing film speed (though the effect on most films is slight, document films are a special case).

Christian,

 

I hope this reply isn´t too late for you. ;-)

 

You´ll find "Reines Soda" without any by-products added in allmost every bigger supermarket and drugstore - at least at "Globus" or "Kaufland" supermarkets and "dm" drugstores.

 

Look out for the green boxes from Heitmann, usually next or close to cloth dyes, soaps etc.

 

http://www.brauns-heitmann.de/brauns_heitmann_1024/produkte/seiten/haushaltspflege/kuechenpflege.htm

 

It is considerably cheaper than the stuff you mentioned (IIRC less than 2EUR per 500g), it is pure enough. I used it as second bath on a two-bath trial and the package states nothing but Sodium Carbonate and it is "food quality" - no range given, no perfume mentioned.

 

I can´t remember the amount of crystal water of this brand. You might want to check the archive at the Phototec forum, it has been discussed in the past - the Heitmann stuff is a big seller there. ;-)

 

http://phototec.de/frame39.htm

 

Roman

More questions on Caffenol:

 

1) I just picked up a stainless steel tank, thinking it would be less likely to be permanently affected by the caffenol residue. Is just runngin it thru a dishwasher (actually we use an industrial one at work for degreasing things, so I wold use that instead of the home one) afterward good enough, or is there a proper way to clean a tank

 

2) Is this a good candiate for developing ancient b/w film recently exposed? With the slow processing, it seems it would be less critical.

 

Thanks

 

Murray