Quote Originally Posted by albada View Post
The wikipedia article on citric acid here says it's an "excellent" chelating agent.
Heavy Fuel Oil is a "great" fuel but I still wouldn't recommend it for your car. When I cleaned limestone residues from my sanitary installations with citric acid, it worked great, but at a temperature, pH level and concentration you would not want in your developer. My recommendation is you take the hardest tap water you can find (let some limestones sit in it for a week), add the amount of citric acid you use in you dev to this water, then add 100 g/l sodium carbonate. If you get precipitation, you likely need a stronger chelating agent.
Quote Originally Posted by albada View Post
I guess we don't know if citric acid will chelate well in a developer, so as PE says, tests must be run. Also, I understand that the Fenton reaction with iron will eventually destroy the ascorbate, but that takes days or weeks, and this is a one-shot dev, so I don't care about Mr. Fenton. Although if I can chelate the iron for free, I will.
I have read reports that Mr. Fenton sometimes takes days or weeks to do his job, but sometimes he is in a superhurry and finishes off all the ascorbate in an hour or so. Therefore I think you should pursue one of two options:
  1. Distilled water is easier to get than most chelating agents, and quite cheap, too. Note, that your concentrate targets people who are very low volume developers, so the cost of distilled water should be irrelevant. If one roll of film fails due to evil Mr. Fenton, it's a pitty but most likely the damage done to humanity is of limited extent. Few pieces of great art come from a tiny portfolio.
  2. Or use a chelating agent which takes care of all these issues (tap water impurities, iron) at once. If DTPA does not dissolve in the concentrate, you might mix it with the sulfite. Maybe Dequest 2010 does dissolve in PG and works well