water filtration for archival prints?

Discussion in 'Miscellaneous Equipment' started by Sean, Jul 11, 2004.

  1. Sean

    Sean Admin Staff Member Admin

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    Hi,

    We use rainwater as our main home water supply, and with the darkroom I have had a city water line put in just for that. The chlorine smell is very strong in the city water (maybe because I am used to rainwater?). How does chlorine and other city water crud affect archival print making? I am also weary of the filters that can be hooked to the waterline. Reason being is I have a water distiller and at my last house, with city water, there was muck left in the boiling chamber after doing a cycle -we then had a filter put in (looks like the ones many have on their darkroom sink), I then filled up the boiling chamber with the 'filtered' water and ran the distiller through a cycle -end result was same muck in the boiling chamber after the cycle. So what do you guys do for filtration? double up on the filters? triple up? Use special filters, etc? Thanks!
     
  2. dr bob

    dr bob Member

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    Sean: the muck you are getting is deposits of the magnesium and calcium salts and other nastys dissolved in the tap water. Because they are dissolved, filtration will not remove them. Heating the water to boiling will cause most of the salts to precipitate which is why you always have the muck in the distiller(s). The only way to insure removal is by ion exchange. I used this technique in my r&d work with success. It is somewhat expensive but available in most places of the world. You should have a means of dropping and regulating the pressure to aid in flow control. I had two columns in series, one rough and the second fine. Water came out 90 megOhms by conductivity measure, which is pretty good. The columns I used were of transparent plastic which allowed visual tracking as the exchange resin was used.

    Or you could just boil the water in a kettle first and decant it into your still. OBTW, I did filter the incoming water but this was probably unnecessary given the efficiency of the ion exchange process.

    One caveat: there is or was a company selling a device claimed to remove hardness by wrapping a coil if wire around the incoming pipe and hooking it to their "secret square wave" generator. Fraud! I don't know how they do get by with these things.
     
  3. mark

    mark Member

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    Having worked extensivly with negatives and prints made by the Kolb Brothers-The famed photographers of the Grand Canyon, I can say that the water they used to wash both negatives and prints has had little effect. They washed their negs in a stream and the prints were washed there as well or in water carried from the stream. The stream was dirty. Think about what people used in the past and the lack of clean water in their processes and think about the number of prints and negs that are still around in perfect condition.

    I am not saying don't try to remove the junk. I am saying don't fret over it too much. If you put water out over night and let it sit the chlorine will evaporate and the smell should go away unless you water folks really dump the stuff in.

    I can't imagine using rain water for much of anything because we get so little of it. Living in a drought sucks.
     
  4. Stan. L-B

    Stan. L-B Member

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    Hello Sean.
    Chorine does effect most chemical that come in contact with it. For photographic purposes it will reduce the strenght of the chemical it is mixed with.

    I use distilled water where possible for mixing chemical to make stock solutions.

    For washing film and prints, I put the water through a domestic filter that can be re-newed cheaply. When away from home, I have found bottled drinking water to be satisfactory and when really in isolation, rain water. In Scotland, and other parts of the UK avoid acidic sources. The London area and much of Southern England, the hard water is fine provided a little wetting agent is used for the first and final wash.