In the Jan/Feb 1995 issue of Darkroom & Creative Camera Techniques, page 2.:
Reader Jim Gupton in NC wrote in about an old friend, Harold E. Ingraham, founder of Heico, whom Gupton knew in the Navy in Oahu in WWII. Ingraham was a chemical engineer who noticed that the film and prints from the Pearl Harbor base photo lab discolored much faster than those processed at sea. He compared equipment and procedures and found the only difference to be that ship-based labs used sea water for 99% of washing, with only a quick rinse in fresh water at the end. Ingraham later founded Heico, and PermaWash was formulated to be identical to Pacific Ocean seawater.
The article doesn't mention with what form of water it was to be diluted, so we've still got plenty about which to speculate. ;-)
I don't see how a chelating agent in the final wash can prevent deposits of minerals upon drying. I don't use anything in the wash but what comes up from my well. I squeegee most of it off. If there were a problem, I would use distilled or rain or dehumidifier water, which are less likely to have dissolved minerals, in the final rinse. Calgon or EDTA may prevent precipitation in developer solutions, but the minerals are still in the water in addition to the chelating agent and remain on the film after drying.
Originally Posted by Lee L
If you use the tap water plus Calgon, you shouldn't need a subsequent rinse in Photo-Flo. The Calgon will do essentially the same thing; by softening the water, it will run off the film more evenly. Or if you really want, just add your photo flo to the Calgonized tap water.
Originally Posted by Lee L
I used about a teaspoon of water-softening crystals per liter of tap water. This can be re-used quite a number of times. If your film is washed, no contamination occurs; it's just for dunking a final time to get the water to run off the film while drying without leaving calcium deposits behind.
OK - so it is just anecdotal speculation on your part and not the result of any definitive testing.
Originally Posted by gainer
Did you compare the temperature of the water to make sure that it is not the cause. I suspect that your well water may be cooler than city water that is sitting around in tanks above ground (warmer at least most of the year).
Kirk - www.keyesphoto.com
Originally Posted by Maine-iac
I will probably still used distilled, or perhaps the filtered spring water for my last rinse, with very dilute Photo-Flo or LFN. I was just hoping that the cheaper alternative of Calgon + tap water for the preliminary washes would lessen the chances of calcium deposits forming on the film and persisting through the last rinse in distilled water. I can only distill a gallon at a time, which takes about 5 hours with my current 'still, so the distilled water is expensive in both time and electricity, and if I do as much darkroom work as I'd like, I'm not sure I could keep up the distilling schedule.
The first time I processed film in this water, even with Photo-Flo in the final tap water rinse, I looked at the negatives after they dried and my first impression was that someone had dragged them through cobwebs while wet.
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Anything added to the wash water will add that thing to the
emulsion. I've very hard water and use distilled for everything;
79 to 99 cents/gallon. If you also have that problem do the same.
The sodium and ammonium-silver-thiosulfate complexes are
soluable and will wash out. There may be impurities in wash water
which form insoluable silver-thiosulfate compounds which can
precipitate in the emulsion.
If in doubt of water quality ALL post fix washing should use
distilled water. Dan
Dan and others,
Originally Posted by dancqu
Thanks for the information. On my last run I tried the spring water (10 cents/gallon) for the first washes, with distilled on the last wash and for the LFN bath. The spring water is much less hard than the tap water, and is filtered. I got very clean negatives, so my problem may be solved. I can produce enough distilled to handle the developer and final wash and LFN bath without doing it 'round the clock, so this may be my best practice.
This will also make my wife happy, as it will assure her of a more constant supply of the water she prefers for her coffee, tea, and drinking straight up.
Actually, I have some Calbe R09 from J and C that I'm just starting to test, and at 1+40, it looks like McDonalds coffee. Fortunately, I don't drink coffee or developer, and my wife brews her coffee stronger than McDonalds and never drinks in the darkroom.
By the time the prints have sat in the washtub overnight, the difference in temperature can't be much. Our city water was right cool in the winter anyway. If you are afraid of my anecdote, you can test it yourself. That's what I do.
Originally Posted by Kirk Keyes
You do know, I'm sure, that if you want to remove the emulsion from its base in a hurry, you need onle immerse it in a Clorox solution. Chlorinated water is just slower.
Kirk said: "My 18 Ed. CRC Handbook of Chemistry and Physics lists the solubility of CaSO4*2H2O (Gypsum) as 0.241 g/100 ml at 0C and 0.222 g/100 ml at 100C for water. Not a very significant difference, as there is with most compounds, which actually increase solubility as the temperature of water increases."
That's strange. So does my copy. But what does it say about calcium carbonate? What if the heating, combined with the CO2 in air and water, changes the sulfate to the carbonate?
That's not the problem. The problem is that cold water is saturated with calcium sulfate, it will precipitate as the temperature increases. Most other substances will dissolve as the temperatures go up, but gypsum will not.
Originally Posted by gainer
With the sulfite and thiosulfate we add to the wash water, the sulfate concentration in the wash will be high enough that it is a real problem if the water is hard. Both sulfite and thiosulfate will oxidise to sulfate, BTW.
-- Ole Tjugen, Luddite Elitist