An, uh, "unusual" developer accelerator
PE or someone else who understands chemistry; perhaps you can chime in on this...
I was flattering myself, as I am want to, by reading a chapter on "Replenishment of Developing Solutions" in C.B. Neblette's, "Photography; It's Materials and Processes" 5th ed., 1953, when I stumbled across this:
"Additions to Developing Solutions"... "...UREA -- Urea has a softening action on gelatin which may be used (1) to increase the speed of development, (2) to revive partially exhausted developers, and (3) to facilitate development at a low temperature.
The addition of fairly substantial amounts of urea enables development to be carried on at temperatures as low as 40 degrees F. without greatly increasing the time of development and with only a slight loss in emulsion speed. At 40 degrees F. from 300-400 grams of urea per liter are required and the time of development is from 2-4 times greater than 68 degrees F. "
My idle curiosity is, if you are out in the field shooting film, decide to process your roll of HP5 in the leftovers of your Starbucks Gold Coast coffee mug, would a quick pee in the soup help?
Photographically, that is...
Now it IS a honest question; the gross-factor not withstanding...
I think the answer is in the quote from the book you quoted. "Urea...may be used to 1. increase speed of development, 2. revive partially exhausted developers, 3. facilitate development at low temperature."
Sounds to me like this is an accellerant, rather than a developer.
You go try it, and report back. Don't save your "used" developer though.
I'd be curious to see how well it works (with real urea). Urea is a potent denaturant of proteins (like gelatin) and so, while I can see how softening gelatin might change the development properties, there's probably a fine line between that and simply turning the emulsion to mush.
My guess is also that this technique might have worked better in the 50s when emulsion layers were (IIRC) thicker.
Yes, I was asking if urine was of a sufficient strength to be a reasonable developer accelerant to something like cafinol -- guess I should have been more clear, so I willl rephrase it;
Originally Posted by PHOTOTONE
Does urine contain enough urea to be reasonably effective as an accellerant to any type of developer?
OK, I will try that and see how it works...
Now since the Urea you are going to get is in, ahem, liquid form, and the concentration is all over the place. You really need to do a controlled test, where you use production from the same time of day, for each test. I would guess you would replace "some" of the liquid in your developer mixing with this "special" Urea concentrate.
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Urea contains other ingredients such as catechols when it comes in liquid form from the human body . See Haist for further information.
Urea, NH2-CO-NH2, is a development accelerator because it swells gelatin and improves diffusion, but it has a counter effect. The swelled gelatin is a longer diffusion path, and the gelatin is softer.
So, too much can cause reticulation and slower development.
You must be careful with these types of accelerants.
Good luck to you.
Finally, we can prove that photography is in our blood, and in our ... well you know...
Originally Posted by Photo Engineer
See? Humor does have a place in photography.
From The Film Developing Cookbook, by Stephen G. Anchell and Bill Troop, p. 25.
Originally Posted by Photo Engineer
"One interesting attribute of pyrocatechin is that this toxic benzene chemical is a constituent of human urine. How or why the human body manufactures pyrocatechin is something we will leave to future generations of scientists — or theologians. Perhaps the Creator forsaw a time when developing agents would be in short supply but film would be plentiful?
1. The author of that statement gets an A+ for humo(ou)r and irony.
2. Could it be that the time of the rapture is closing in on us?
Who/What is exhausted
This second use:
"(2) to revive partially exhausted developers".
Does that refer to the chemical or the chemist?