Water quality

[Lee L]

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. ;-)

Lee L

 

[gainer]

So is there a recommended amount of Calgon per liter of hard water for a final wash, or is that dependent on the concentration of calcium-magnesium carbonate in the water? I've now live in the only location of 7 where I've processed film that leaves a spiderweb of calcium deposits on my film unless I use something other than tap water. I'm currently experimenting with a cheaper local spring water at 10 cents/gallon rather than the river sourced tap water I've been distilling one gallon at a time. I'd like to try tap water + Calgon for washing if that will work, then a final rinse in either spring or distilled water with Photo-Flo or LFN.

If you drive past our city reservoir, you can see a large pumping station with a white sludge pond where they try to get some of the minerals out of the water, but apparently a lot of it remains.

Thanks,
Lee

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.

 

[Maine-iac]

So is there a recommended amount of Calgon per liter of hard water for a final wash, or is that dependent on the concentration of calcium-magnesium carbonate in the water? I've now live in the only location of 7 where I've processed film that leaves a spiderweb of calcium deposits on my film unless I use something other than tap water. I'm currently experimenting with a cheaper local spring water at 10 cents/gallon rather than the river sourced tap water I've been distilling one gallon at a time. I'd like to try tap water + Calgon for washing if that will work, then a final rinse in either spring or distilled water with Photo-Flo or LFN.

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.

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.

Larry

 

[Kirk Keyes]

Chlorine softens the emulsion. I noticed that if I left a print in the wash water it would keep its emulsion on longer here in my well water than in the chlorinated water I had in the city. That city water was hard also, so I'm pretty sure calcium and magnesium content is not the difference.

OK - so it is just anecdotal speculation on your part and not the result of any definitive testing.

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

 

[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.

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.

Larry

Thanks Larry.

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.

Lee

 

[dancqu]

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

 

[Lee L]

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,

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.

Lee

 

[gainer]

OK - so it is just anecdotal speculation on your part and not the result of any definitive testing.

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

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.

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.

 

[gainer]

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?

 

[Ole]

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.

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.

 

[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.

Well, chlorinated tap water will be about 1 mg/L free Cl2, Clorox is about 53,000 mg/L free chlorine. That's quite a difference!! And remember that the pH of the Chlorox is about 11.4 according to the MSDS. That's a pretty high pH - I'm sure that has a huge affect on the hardness/strength of an emulsion.

I still think you are jumping to conclusions about the chorine in tap water. Especially if the water is sitting overnight, at 1 mg/L, reacting with your paper. So you have a 25 gallon tub, that's 100 litres of water, that 100 mg of chlorine. That's not much.

Kirk

 

[gainer]

All I can say is do the experiment.

 

[gainer]

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.

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.

We have at least two uses for water. we use it to dissolve developing agents and we use it to wash developed and fixed materials. Sometimes we even bathe in it. I don't worry about calcium in the wash water. I don't even worry much about residual sulfate or thiosulfate since I read about findings that a little of that left in prints may make them last longer. The only reason I might have to boil water (other than to keep busy during childbirth) is for mixing developers.

Magnesium sulfate is very soluble. Magnesium carbonate is not. Calcium sulfate carried in ground water, dripped from cave ceilings and reacted with CO2 is responsible for a good portion of what we see as stalagmites and stalactites. The carbonate is much less soluble than the sulfate for both magnesium and carbonate. You could clear most of the calcium and magnesium out of hard water by bubbling CO2 through it. What is left to combine with the sulfate ions? If there is enough heat, you may evolve SO2. I don't know. But I do know that heating hard water in the presence of air leaves a precipitate. I doubt that you have free sulfate or sulfite ions. Sulfurous acid with heat gives of SO2 and leaves water behind or sends it off as steam. I have forgotten why we were being so scrupulous about this. Hav we come across some ruined photos by past photographic geniuses who did not know all this chemistry?

 

[Ole]

... You could clear most of the calcium and magnesium out of hard water by bubbling CO2 through it...

Bubble MORE CO2 through it, and the solids dissolve again as the pH rises from increased H2CO3 (CO2 + H2O). Some stalagtites are formed by CO2 escaoing from the water, giving a drop in the pH whick leads to CaCO3 precipitating.

It ain't always easy...

I have forgotten why we were being so scrupulous about this. Hav we come across some ruined photos by past photographic geniuses who did not know all this chemistry?

I have no answer for that question!

 

[David H. Bebbington]

I have forgotten why we were being so scrupulous about this. Hav we come across some ruined photos by past photographic geniuses who did not know all this chemistry?

My 2 cents worth: I live in an area where the water is hard (dissolved limestone). I used to be scrupulous about using filtered water (Brita filter jug, I think this is activated carbon), but when I went to a 15-ilter tank line for film processing, laziness got the better of me and I used straight tap water. I have seen no difference. I finish all sizes of film by putting a few mil of washing agent in the final wash water (tap water). The amount needs to be such that there is a unbroken film of water on the photographic film when you lift it out of the water, too much and suds will form. I virtually never experience drying marks. I take care to hang the film slightly off the perpendicular so that water drains to the edges.
The only time I have had problems with water is with print toners that involve bleaching - using tap water has resulted in a definite powdery deposit on the prints.

Regards,

David

 

[m_liddell]

I've had a terrible time with tiny particles on my negs. I now use distilled water for the dev and the final rinse, but even at 8x enlargment there are some white spots in the print. My early negs are so bad I had to scan them in the end.

The distilled water costs are killing me (£3.50 for 5L), and I can't find it anywhere else. Going to try the supermarket bottled water instead.

The only thing saving my prints right now is I never enlarge 8x from 6x7 negs but I've had to pretty much ditch 35mm since I cannot get a clean 8x10 print.

Any advice would be great!

 

[David H. Bebbington]

I've had a terrible time with tiny particles on my negs. I now use distilled water for the dev and the final rinse, but even at 8x enlargment there are some white spots in the print. My early negs are so bad I had to scan them in the end.

The distilled water costs are killing me (£3.50 for 5L), and I can't find it anywhere else. Going to try the supermarket bottled water instead.

The only thing saving my prints right now is I never enlarge 8x from 6x7 negs but I've had to pretty much ditch 35mm since I cannot get a clean 8x10 print.

Any advice would be great!

I would bet the spots are caused by rust particles from your water pipe. Paterson and others sell a filter which you can fit to your tap/faucet. I would think this will fix the problem, maybe in conjunction with a Brita filter jug. I think distilled water is overkill!

Regards,

David

 

[Kirk Keyes]

What is left to combine with the sulfate ions? If there is enough heat, you may evolve SO2. I don't know. But I do know that heating hard water in the presence of air leaves a precipitate. I doubt that you have free sulfate or sulfite ions. Sulfurous acid with heat gives of SO2 and leaves water behind or sends it off as steam.

Partick, CO2 dissolved into water will form H2CO3, carbonic acid. When this reacts with your Ca and Mg sulfates, it will precipitate out the carbonates, but it leaves the acid of the sulfate. That is sulfuric acid, not sulfurous acid. It's simple stoichiometry. (I don't get to use that phrase too often.) If you really boil that down, you will release sulfur trioxide, not SO2. But anyway, as you say, this is getting far away from the original, mutated thread.

 

[Kirk Keyes]

I've had a terrible time with tiny particles on my negs.
[...] Any advice would be great!

Have you tried an inline water filter? Perhaps your problem is not with mineral deposits but with particulates in the water.

For wash water you only need a low temperature filter (these often have a blue plastic housing), and you can find them for pretty cheap. Get a 20 micron filter for it.