Quote Originally Posted by Alan Johnson View Post
In the UK the maximum limit for copper in drinking water is 2mg/L and for iron 0.2mg/L.I don't know the US values.
I daresay there may be high copper concentations in the UK which has mostly copper pipes and high iron concentrations in the US (which has mainly iron pipes?).
The Fenton test consisted of adding Fe and Cu ions (iron and copper) to the developer to simulate iron and copper pipes, and impurities in chemicals. I added 1 mg/L each of Fe(II) and Fe(III) ions using ferrous sulfate heptahydrate and ferric ammonium sulfate, and 2 mg/L of Cu(II) ions by adding copper sulfate pentahydrate. Jerry: I used ferrous sulfate because PhotoFormulary doesn't carry ferrous ammonium sulfate. Was this change a mistake? The separate beaker of these ions at 100x concentration was a cloudy light-yellow. Surprise: When adding 1 ml of it to the developer, the developer turned light purple. I'll guess the ammonia is reacting with something.

I waited 50 minutes before developing, to simulate easy-going one-shot usage. Here are density-curves with and without these added ions:


The curves match well, so the Fenton reaction had no measurable effect. Nor did the purple, fortunately.
Earlier tests show that hard water causes cloudiness starting at 30-45 minutes after mixing. So all should go well if this one-shot is used within 30 minutes of mixing.
I guess my next step is to mix the concentrate and test its longevity and compatibility with various films. Comments are welcome as always.

Mark Overton