processing film with well water?

[greybeard]

gainer: What soluble compound of calcium or magnesium might be in water? The hydroxide is somewhat soluble. The carbonate is formed in caves when water containing some of the hydroxide comes in contact with CO2 in the atmosphere. Over years, stalactites and stalagmites are formed out of limestone. When you mix carbonate developers with hard water, you get cloudy developer from the calcium and magnesium hydroxides. You will see it very soon after mixing...

This is close, but maybe not quite right---limestone is calcium carbonate, essentially. Carbon dioxide from or decaying vegetation (or other sources, such as volcanoes) dissolves in water to form carbonic acid, which dissolves calcium carbonate by converting it to calcium bicarbonate, a substance that is much more soluble. In caves, the lower carbon dioxide concentration in the air allows the reaction to go the other way, releasing carbon dioxide and precipitating the carbonate as limestone again. Calcium in water is usually due to a high bicarbonate concentration, which is why boiling it causes a precipitate of calcium carbonate to drop out (the so-called temporary hardness). Calcium hydroxide is much more soluble than the carbonate, but reacts with carbon dioxide until the carbonate/bicarbonate equilibrium is reached; this is the basis for the "limewater" test for carbon dioxide (make limewater by saturating water with calcium hydroxide; bubble your breath through it and the carbon dioxide will cause calcium carbonate to precipitate out)

Magnesium sulfite seems to be reasonably soluble, but the sulfate (Epsom salts) and chloride are very soluble. Of all the possible culprits, it seems that calcium sulfite would be the only thing that could arise from well water and not be soluble in acetic acid; it seems that Bethe's problem might be sulfur caused by bad chemistry, or some sort of soap formed by organics in the water, alkali from the developer, and calcium or magnesium. What is odd is that most of the potential culprits should form precipitates in the solutions, and not streaks on the film at the drying stage. The metallic soap (aka scum) idea is motivated in part because it would probably adhere preferentially to naturally hydrophobic surfaces, like the non-emulsion side of the film.

We really need a photographic chemist in this discussion!

 

[gainer]

Maybe some of the stuff you put in dishwashers to prevent soapscum on the dried dishes would help, at least to identify the problem.

 

[winger]

it seems that Bethe's problem might be sulfur caused by bad chemistry,

I would think sulfur would be yellow. All the chemistry was brand new and familiar.
After some experimentation (if you don't like wiping negs, please stop reading here), I discovered that a wipe with a very lintless soft cloth with vinegar on it, then a wipe with distilled water will remove the residue. Yeah, I know it's more contact than many are comfortable with, but I tried soaking and non-contact measures and they didn't work.
I think what it is is just very stubborn limescale (basically calcium carbonate). I've never seen any as stubborn as what I have to clean off the shower, and this is probably the same stuff. Chances are, I washed for too long with the well water and probably will make all the chemicals with distilled next time, too (not just the developer). The soaks in distilled and even vinegar just weren't quite enough action to remove the scale, but slight pressure works. I haven't done all the frames (I tested with a few end ones), so I'll do that next. If they aren't printable with the residue, then wiping isn't losing me anything anyway.
And if I were still at the lab, I could test it and see what it is pretty easily. But noooo, that would be too easy.
Thank you all! I'll let you know how it goes!

 

[dancqu]

What soluble compound of calcium or magnesium might
be in water? The hydroxide is somewhat soluble.

The bicarbonates are both much more soluble than
the carbonates. If there is a source of the calcined
forms, and that very unlikely, then the hydroxides
may be present. Dan

 

[gainer]

Just for the record, sulfur has two crytal forms, one of which is yellow and the other pale yellow. The amorphous form is also pale yellow. A very thin layer of either of the pale yellow forms might be indistinguishable from white, especially under incandescent light.

 

[gainer]

The WVU med students used to have a football cheer: "M-G-S-O-4..M-G-S-O-4..EPSOMSALTS..RUN-RIGHT-THROUGH-YOU."

 

[gainer]

Calcium sulfite would be formed from any soluble calcium compound in the water by most sulfite containing developers. Try a developer that has no sulfite or carbonate and see what happens. You can do it with Metol, borax and ascorbic acid.