I never did a comparison, but when I set up my last darkroom, I got info from Kodak on what level of various materials were OK to have in the water and got a water report from my water district. There were so many things that went beyond Kodak's recommendations (including pH and dissolved solids) that I just decided distilled water was better for mixing all my chemicals. Distilled water is cheap.
Contact your local water district--they have a technician who would be happy to talk to you about your water quality. They do regular testing of the water for government requirements, and are probably lonely and be happy to chat! Anyhow, you pay for their services, so why not use them?
I must admit, I've never given it much thought, but then I live in an area with the softest water in the country
"Flatter Me, and I May Not Believe You. Criticize Me, and I May Not like You. Ignore Me, and I May Not Forgive You. Encourage Me, and I Will Not Forget You."
You know, I'll probably never be able to answer that question with any real certainty. It would take a fully staffed and equipped research lab to get to the truth; who has the time or resources?
Originally Posted by clayne
For the record, I thought that the interim steps didn't matter either. But I was being methodical (old engineers are like that) and testing everything trying to get rid of the grunge. And this is after I'd done all the "normal" things like washing down the ceiling and walls, cabinets, etc (you wouldn't believe how much dust you'll find on the underside of a shelf, or on the ceiling, until you clean them). I had everything spotless, the darkroom was completely sealed, an air cleaner running, etc. but I was still getting grunge on my film.
So I went to work on my process. First I started with mixing stock solutions with steam distilled water. More improvement. So I knew that there were process problems. I went to one-shot developer use. More improvement. One of the big improvements was to use my fixer as a one-stop. Turns out that tiny bits of silver can precipitate out of used fixer, and the next time you use that fixer they can stick to the film. This was news to me.
Eventually I ended up with tap water in just two places. Dilution of the developer, and washing. Ninety percent of my problem gone, but 10% still hanging in. So I replaced all the water with distilled. Now I've got about 98% gone.
What I think was happening is that I have a fair amount of scale in the pipes just because they are old (this subdivision is 50 years old and the city is starting to tear up the streets replacing both water and sewer pipes). The scale is small, but solid. And it appears to stick to the wet glue that we call an emulsion. Once stuck, no amount of washing gets it off.
So... All I know for sure is that the less tap water I used, the cleaner my film became. What I don't know is why -- I can only speculate. But really, I don't care that much because of the results.
I thought about putting filters on the hot and cold lines, but I had trouble finding filters for small stuff, say down to 5 microns. Before you scoff, I like to enlarge, sometimes over 12x. So those tiny spots become visible - think tiny black dots randomly placed in a nice smooth sky. Painful to my eyes anyway.
What stopped me from going the filter route was a) distilled water is cheap, b) filter systems are expensive and require periodic maintenance and consumables, and c) they don't do anything about the scale in the lines *after* the filters and up to the tap. Any plumber will tell you that the inside of copper pipe, especially if it's got a bunch of solder joints, ain't pretty.
So... it might just be the placebo effect (I did run an extensive series of tests because I couldn't believe it myself, but still...). Yet it's costing me less than $0.10 USD per sheet of 5x4 film in distilled water charges (IOW, it's raised my film/processing costs just 7% while reducing my spotting time to almost nil and raising my photographic happiness immeasurably), which is considerably less than the cost of a filter system would be.
In all, it's a risk I'm willing to take. Especially since it seems to be working.
Geez louise...boiling, filtering, blah de blah blah blah.
Seems like a lot of work, compared to spending a buck or two and just getting a big 10 gallon jug of distilled water and being done with it. I've been developing quite a lot of film lately and I still have a container last me over a month.
'Simple' works. So go with 'simple'.
Exactly. Well said.
Originally Posted by Colin Corneau
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the most interesting past is for instance how pyrocat-hd reacts to water with chloride or calcium compaired to distilled water.
Originally Posted by clayne
Most water districts would also like to see what comes out of the tap. especially in older areas of cities. The reason is, lead.
Originally Posted by voceumana
The water techs do want to know where there is lead in water, so that they can trace back along the lines to find where lead pipe was used, to dig it up and replace it with either copper or plastic. I wonder though, if in 50 years we will find the chemicals in the plastic pipes are worse then the lead ever was, and we will be chasing after it.
See my Blog at http://clickandspin.blogspot.com
The greatest advance in photography in the last 100 years is not digital, it's odourless stop bath....
Lead service pipes are only a real problem in areas with acidic or soft water. If the water is hard, and usually alkaline, the minerals do an excellent job of coating the inside of the pipe with scale, to the point of eventually plugging the pipe. I had a 4' length of lead service pipe that was in the ground for about 40 years, it had more than one eighth of an inch of scale build up in it. No worries about the water contacting the lead. After being hammered to descale, flattening and folding, it also made a nice 12lb counterweight for the enlarger.
Maybe treating tap water with edta and then filtering it should do the trick...
Usually, it makes no difference. If your water is unusually hard, distilled or deionized water may help with some developers. Also, if your water pH is high (or low), distilled or deionized water may be needed for good results with poorly buffered or low pH developers like D-23. Most other things you find in safe drinking water, including chlorine, do not affect most photographic chemistry (although I do use distilled water to dissolve silver nitrate because of the chlorine - a special case). In general, use tap water unless it gives you problems. If it does give you problems, it will probably only be with one or two products or formulas.