Coffee Developers - Why do they Work?

[David A. Goldfarb]

Maybe that's the reason... Coffee drinkers would rather drink their real coffee, and have finally found a use for the dreadful instant stuff. Non-coffee-drinkers, on the other hand, might as well buy the dreadful instant stuff, since they don't know the difference anyway.

Well, exactly. I wasn't going to waste good coffee for this, but there was a dusty jar of instant coffee in the back of a drawer somewhere at the office, so I figured this was the perfect use for it, and it actually wasn't that bad as a developer. I suppose that if I were really desperate at some point in the future and couldn't obtain any normal developing agent, it could be tweaked enough to be something like ABC pyro.

[jim appleyard]

I would think that instant coffee is used because it is instant, no brew time. This lets us have more time time more souping film, not brewing. Just a guess.

[jnanian]

i always thought it was the flavor crystals that developed the film! where are juan valdez or mrs olsen when you need them ?!


http://www.amiannoying.com/(t32zol45...w.aspx?ID=3853

http://www.juanvaldez.com/menu/advertising/juan.html

[wirehead]

We've SECRETLY replaced his film developer with FOLGERS CRYSTALS! Let's see if he notices!

[David A. Goldfarb]

So I came across this interesting document, while searching for information about the hazards of various developing agents--

http://potency.berkeley.edu/pdfs/FDA...alMedicine.pdf

It seems that coffee contains catechol (1.33 mg/500ml), pyrogallol (555 mcg/500ml), and hydroquinone (333 mcg/500ml), where 500ml was brewed from 13.3 g of beans (it doesn't say whether they were robusta or arabica or the brewing method). Caffeic acid (23.9 mg/500ml) is present in much greater concentration than the other developing agents, so if it develops film, it's probably the main factor.

Out of curiosity, I looked around to see if one could obtain caffeic acid to experiment with as a developing agent, and it's not cheap--$9 a gram from one source, $320 for 250g from another source.

[laverdure]

Urine will only develop film if it contains hydroquinone, which can happen due to certain illnesses, or if you ingest the herb uva ursi (coincidentally a great cure for urinary tract infection (I'm not kidding)).

When I was playing around with coffee last year, my more organic chemistry minded friend came to believe it was the phenols which were the primary developing agent. Based on that assumption, we got mint, thyme, and basil to work, before we read elsewhere that it'd been done. I was just messing around, but I hear that mint works much better than coffee. Has anyone actually used wine?

oh, don't know if it's been answered, but the reason people use instant coffee is because the measurements are easier to standardize.

[rwyoung]

I do believe it is the caffeic acid that is doing the majority of the work. Caffeic acid is a phenol and is relatively similar to catechol and hydroquinone but with a few extra bits and its OH pairs aligned a little bit differently. Coffee in general is quite a witches brew of phenols!

I think caffeic acid is still present in decaf coffee, need to get a small jar of instant decaf and try it.

[Jordan]

There are only three possible configurations of dihydroxybenzene: 1,2-dihydroxybenzene (catechol), 1,3 (resorcinol) and 1,4 (hydroquinone). Of these three, only resorcinol is not active as a developing agent (it can't form quinones as the electrons don't "push" the right way). Caffeic acid is in fact a catechol -- its hydroxy groups are in the 1 and 2 positions on the ring -- it also has an acrylic acid substituent elsewhere on the ring that is not terribly photographically active.

I'm thinking of ways to make caffeic acid in the lab, and while it's a somewhat simple molecule, the "hookup" of its structure would make it take a couple of steps -- hence the price.

[Alex Bishop-Thorpe]

All of this is making me wish I'd taken chemistry in highschool. And reaffirmed my decision to ditch the coffee...Very interesting though.

[Steve Smith]

I suppose that if I were really desperate at some point in the future and couldn't obtain any normal developing agent, it could be tweaked enough to be something like ABC pyro.

I tried Caffenol once and thought it was quite good. I would definitely use it again if I had run out of 'proper' developer and wanted to process a film quickly.

I was pleased to find a practical use for coffee. I can't bring myself to drink the horrible stuff!

Steve.