Saving the environment..... all kinds of film washing puts chemicals in the seewage, mainly thiosulphates, the goal is for it all to end there, so there's little difference between washing methods.
However, since fresh water is valuable in most of this world (save for Norway where I live and it's raining most every day....), environnmentally friendly will be saving water as much as possible.
The Ilford method saves water, I use a little better, instead of 3 changes of water I use 7. I use about 4,5 litres per tank, i.e. 2,25 litres per film.
Compare that to constant flow, most will use about 1 litre per minute, hence 30 to 60 litres per tank and 60 to 15 litres per film, depending on 1 or 2 films per tank. I say that 30 minutes wash, constant flow is not enough for archival purposes. At least 60 minutes is required. My films from the 1960's is testimony to that, most washed in running water for 1 hour or more have survived, a few, hastily washed in less time have gly stains and spots.
But consider this, one can be even more thrifty with my adapted Ilford method!
Consider two tanks developed at the same time, 2 films in each. 4 films in all.
Fixer has a thio concentration of 1/4, in the tank is always about 1/20 of the total volume left when draining a tank....
So concentration after first wash is 1/4*1/20 = 1/80, second wash is 1/1600 and so on, Ilfords method says that about 1/32000 concentration is *enough* (I happen to slightly disagree there.....)
In the wash, first start with tank#1, first water is flushed down the drain, second water is used as first water in tank#2. Go on for 7 changes of fresh water in tank#1, use this water in tank#2, and finish with to changes of fresh water in tank#2.
You have now washed 4 films to archival standards with just 5,2 litres of water! That is less than 1/25th of what running water would use. With less concentration than running water, running water always leaves a gradient, i.e. the only way to rid Thio is to dump out everything and put in all new, fresh water....
Thio concentration in tank#1 is theoretically down to better than 1/500 000 000 concentration after 7 changes, and tank#2 is even better than that, after 8 changes, closer to 1/10 000 000 000 .
The numbers adds up quickly with this method.
It is safe to say theres no Thio or other chemicals left after 7 changes of water! What comes out in the end is drinking water with a little film-base effluents in it.
Last edited by Removed Account2; 07-27-2010 at 03:35 AM. Click to view previous post history.