This is an old idea, and one that died when Polaroid film came out. A single bath of chemicals to develop a film as quickly and simply as possible (and used on direct positive photographic paper you have the necessary means for those once ubiquitous photobooths that used to take our passport photos in a simpler age). The trick is to balance the rate of development with that of fixing. B&W developer is doing one job: depositing growing metallic silver crystals on the nidus of a silver bromide molecule that has been reduced to silver by a photon. Fixer comes along afterwards, usually, and dissolves the unexposed silver bromide from the film's emulsion. In the end, you have metallic silver where there was light, and clear film where there was darkness. This is a negative, and exposing photo paper through it will make a negative of that, which by some alchemical arithmetic is a positive. Now for a monobath, we need the developer to work on the exposed areas, while the fixer at the same time is is working on the unexposed. Remember, that unless you photograph things that are literally just black and white, no greys, all areas of the film have some exposure and it's just the amount that varies. Most fixers these days are ammonium thiosulphate and are buffered to be acidic, which makes them work a bit faster. If we make our monobath strongly alkaline, we can slow the fixer and let the developer have a crack at the exposed silver halides before the fixer dissolves them. Donald Quall is a gent who has been experimenting with making such a brew, since the last commercial monobath hasn't been sold for years. He uses lots of ammonia to get a pH of 9.5 (wear gloves!) Take 16ml of Kodak HC-110 US Concentrate, and add 180 ml water, then 10ml Ilford Rapid Fixer concentrate, then 50ml household ammonia (usually 5% solution ammonium HCl) and mix well. Warm to 24-26ºC, then develop negatives in total darkness for six minutes with no agitation. It is said to be OK to turn the light on after two minutes, but I didn't. Try to hold your breath for the six minutes as the ammonia fumes will be strong.
Then was for five minutes with room temp water. The result is very fine-grained and quite contrasty.
Next weird experiment is in train. I have cut some 10x8 photographic paper into quarters in the dark (safelight OK as orthochromatic) and loaded it into film holders for the 4x5. ISO will be 3. Yes, just 3 - some modern digital cameras can make an image at ISO 25,600. These can be used as paper negatives for contact prints, scanned and then inverted to get the image desired, or even developed by a reversal process that will make a positive image rather than a negative (think slide film versus negative film). Might be fun.
Chris
