The coffee and the vitamin C are the developing agents. They should act as a synergetic pair, so combined they are more active than a brew with either of them could be. The soda is the accelerator which raises the pH for the developing agents to be able to transform silver halide salts into metallic silver. To make the brew stronger, you can increase any of these, but:
1: There will likely be an optimum ratio of coffee to vitamin C. Diverging from this ratio will have limited effect, so if the ratio is already optimal, you don't gain much by adding either coffee or vitamin C and you'd have to add both.
2: Since especially the coffee part is a poorly controlled substance chemically speaking, there's likely room for optimizing the coffee:vitamin C ratio provided you have a way of controlling the strength of the coffee part. I.e. always use the same brand/source of coffee at the same strength/brew procedure.
3: Adding soda will increase activity up to a certain point where the pH won't rise anymore. There's a tapering effect to this; adding more soda may initially make a significant difference, which gets less and less as you keep adding soda. A pH meter helps in analyzing what's happening but I assume most the caffenol users don't have one. Once additional soda doesn't make a difference, you could try adding sodium hydroxide (e.g. drain cleaner). At a very high pH you may experience problems with fogging and ultimately emulsion stability issues, although the latter tends to be not so bad with most modern films.
And there's probably more caveats, such as the question which compounds in the coffee are actually the active ingredient, what the optimum pH is for these ingredients in combination with vitamin C, etc.
Merry Christmas and have fun experimenting.
Thank you, great information in both posts. I tried a recipe with more of everything, Anna slightly different proportions. The negatives came out much better.Recent discussion:
IMO it is not known for sure if, in addition to caffeic acid, coffee might contain another ingredient X which is active in the development process.Caffenol's ascorbic acid activity
Even though I search for quite long, I haven't found an explanation for this yet. - Ascorbic acid is NOT superadditive with chlorogenic/caffeic acid; both are in the same group as HQ (from SA point of view). So, ascorbic acid is NOT restoring the other developer agent. They are both working in...www.photrio.com
Also not known for sure if caffeic acid is regenerated by ascorbate [superadditive].
Finally, ascorbic acid alone [without coffee] is known to be relatively inactive at pH 10 and quite active at pH 13 but not much is known about its activity beween these limits.
May be some kind of project here, but not easy.
There was a thread here a while back, someone tried pure caffeic acid with soda and found it didn't develop film at all; mixed with ascorbate, there was no more activity than the ascorbate alone. It's not caffeine, either -- pure caffeine was tested, and decaf coffee works the same as regular.
What about used coffee grounds? Is there enough mojo left in them?
people have boiled potato skins in water, and used that to develop film in place of the instant coffee.
For those who wonder about this, it's no lie at all: http://ascorbate-developers.blogspot.com/2012/04/i-was-making-dinner-for-boys-other-day.html
For those who wonder about this, it's no lie at all: http://ascorbate-developers.blogspot.com/2012/04/i-was-making-dinner-for-boys-other-day.html
With soda the pH changes to over 10 and they break down [post 13].
From a link posted by @relistan this table shows the ingredients of roasted coffee beans:
The main component is chlorogenic Acid.The content of polyphenols in coffee beans as roasting, origin and storage effect - European Food Research and Technology
Coffee, one of the most popular beverages in the world, contains many bioactive compounds. The aim of this study was a comparative evaluation of the content of bioactive compounds in organic and conventional coffee (Coffea arabica) originating from Brazil during 12 months storage. The content of...link.springer.com
With increasing pH and time in water the chlorogenic Acid=5-CQA breaks down to quinicic acid =QA and caffeic Acid=CA, fig 3, LHS.
Originally I found that caffeic acid was not as active as coffee:
This may be due to leaving out quinicic acid and possibly other ingredients in @relistan's table.Caffeic Acid-fill of beans
Caffeic acid is often mentioned as the possible developing agent in the instant coffee based developer Caffenol: http://caffenol.blogspot.de/2010/03/caffenol-c-m-recipe.html I compared the activity of Caffenol-C-M with that of a similar solution in which the 40g/L instant coffee (Lidl Arabica)...www.photrio.com
The main active substances in caffenol would then be caffeic acid and quinicic acid plus minor ingredients from the table, plus ascorbic acid if added.
Contents of chlorogenic acids and caffeine in various coffee-related products - PMC
Keywords: Chlorogenic acids, Caffeine, Caffeine/CGAs ratio, Coffee shop, Asian countrywww.ncbi.nlm.nih.gov
Very curious to see the wide spread on cholorogenic acids content of differents brewed coffees.
turkish brew
One member here, as I recall, was using espresso brewed coffee.
I wonder if anyone has boiled oak galls to make an 'organic' pyro developer. Will real pyro work better with the all the oak gall's ancillary compounds - like coffee beats caffeic acid.
I was always under the impression that the combination of an acid and a base produced a salt. So it would seem ascorbic acid in a s. carbonate developer formula would turn to sodium ascorbate and CO2 gas. I imagine it is the ascorbate ions that produce developing activity. Table salt has no developing activity, just the opposite, but then I can't see that chlorine ions would develop silver grains.
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