Just to add to the confusion, the wash method in my "Kodak Black & White Darkroom DATAGUIDE" (the capitals are on the book cover, I'm not shouting ;>) ) advises that after using hypo clearing agent the wash is for 5 minutes with a constant flow that allows for a complete change of water in 5 minutes (I read this as two tanks of water). It also mentions, as a speedier option, emptying and filling the tank 10 times but does not make note of any wait time between each fill and dump cycle.
The wash time without the hypo clearing agent is 30 minutes, but only requires about 5 or 6 tank volumes of water (the suggested flow rate is 1 tank per 5 minutes).
It seems to me that none of the methods mentioned by either Ilford or Kodak uses an inordinate amount of water.
Whilst not doubting Ron's (Photo Engineer) undoubted knowledge and understanding of photographic chemistry and other technical matters I have to report that I have used the Ilford Method for in excess of 20 years without any problems whatsoever. I do 5-10-20-15-10 and 5 inversions with a change of water at 68f for each step.
I have to agree that the Ilford method would have to have some merit or they would not publish it at all. Also IIRC, this method was developed when all of the British Islands were having a bit of a water shortage.
I would have to say that this is the minimum wash condition acceptable.
I would also add that IIRC, England uses ozone to purify water, whereas the US uses chlorine. This puts a tiny amount of peroxide or oxygen into the English water supply and peroxide is used to eliminate hypo.
All of these differences add up to say " use what works ".
Originally Posted by Photo Engineer
That English purification methods puts peroxide into the water which helps eliminate hypo is interesting and prompted me to write the following:-
When I first started photography an old journalist told me to put a "splash" of peroxide into the tank and agitate for a couple of minutes and the film would be washed, hence speeding up the whole operation. I did this for a few months and then noticed that my negatives were changing colour, I recall being told it was dichroic fog that could be cleared by immersing the negatives in a mixture of citric acid and thiourea. I tried this on a negative and watched with horror as the emulsion turned to a jelly, slid off the base and floated away down the kitchen sink. (No darkroom in those days)
Luckily I had made no worthwhile negatives up to that stage in my photographic life so nothing was lost but I did learn a valuable lesson not to believe everything I was told and to fully check out obscure hints and tips before I employed them.
Uh... I don't know about you but I grew up with well water so I can tell if tap water has chlorine in it or not because, to me, it smells like a swimming pool. At least in North London, there's chlorine, not ozone because it'd smell different wouldn't it?
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While I was in London visiting the Kodak facility at Harrow, I noticed the smell of the water and the lack of chlorine in it. I was saying at a hotel on Drury Lane near the White Hart. I was told that they used an oxygen (ozone) treatment for purification.
Thiourea can soften emulsions and increase swell as can urea. Peroxide is used in wash aids IIRC.
Don't assume that US water systems haven't used ozone. I know for a fact that the City of Dallas (TX) Water Utilities uses ozone as part of their water treatment program. However, US regulations require that there be a residual chlorine level in the water at all points in the distribution system. That's why you can smell chlorine in US water supplies.
Yes, true. Go here: http://www.dwi.gov.uk/pubs/tap/index.htm#3 for an explanation of the fact that ozone can decay in the distribution system and therefore chlorine is added as an extra precaution.
Also, remember that peroxide is used in hypo eliminators.
In addition, the type of water - hard, soft, distilled, warm, cold and the film thickness all determine wash rates. This is NOT a simple subject.
That is why I say 'test for your conditions' and use what passes the standard test for hypo and silver free film.
There are a few threads on this:
Originally Posted by Erik Hartmann
I'd recommend leaving your water running for 10 mins or so and dunking the film for 10, 15, 20... times etc and exchanging the water regulary.
Thansk to all of you for given me some knowledge on this subjekt.....
I think that I will go on using the Ilford Method...
Wather in Copenhagen is free of chlorine and ozone......