Interesting thread, Mick. Just curious about the need for filtration. Partly inspired by your own developer mixing, I've been mixing my own for a few years but haven't seen a need for filtration.
Kevin, I have been using straight tap water forever and of late, water filtered through our Royal Doulton ceramic filter in our camper whilst on the road.
The problem is not an issue with the water, so to speak, just the little things that are sometimes in the solution(s) I have mixed up.
In most cases, when I have come back to a tightly stoppered jar of stock solution, where as much atmosphere as possible has been eliminated by the use of glass marbles, I can and do find very slight precipitate hanging around. It is mainly this precipitate that occurs after a stock solution has been standing around for some time, I have felt a need to eliminate.
Through simple observation of my newly developed films, I noted that on the odd occasion one or two pieces of solid material was embedded into the emulsion. As Gerald mentions, if it is removed, you are left with a hole.
This is reasonably easy to fix a B&W print, but in the days when I was doing heaps of colour negative and colour prints, print fixing for virtually flawless colour prints, is a real issue.
Having negatives as clean as the proverbial whistle from the get go, is so much easier. So I started to filter my film developing stock solution immediately prior to diluting it with tap water, finding that this eliminated almost all solid stuff being embedded into my developed film.
The very first time I saw photographic solutions being filtered, was up Cape York around 40 years ago while camped along a river. We sourced all water from that river for washing, eating/cooking and film developing. All the water for photography purposes was filtered through a group of ladies nylon stockings. By having about 15 or so layers of the stocking material stretched on a wooden frame, the water was poured through a couple of times. There wasn’t much super fine stuff being caught, but there was a surprising aggregate of stuff. There was another issue up there that was more of a source of film contamination, which were all the insects flying around and landing on the wet films as they were drying after being hung on tree branches.
I started filtering my stored stock solutions shortly after that experience. I did manage to eliminate quite a lot of solids from my C41 bleach that I regenerated session after session. Filtration of this component of my C41 process was pretty much mandatory, as I generally made one litre last for close to one year with around 500ml added from processing losses per annum; more or less.
Another reason for filtering solutions, is when you mix solutions from raw stock powdered chemistry. Some, but not all mixed powder solutions, have a reasonably good chance of having some tiny precipitate that just didn’t go into solution. The miscibility of liquid store bought chemistry is usually far better as far as my limited experience has found out, compared to powdered chemistry.
Paper filtration was seen by me as the easiest way to remove this precipitate, still is.
I started this thread after reading about lab grade filtration paper suggestion in another thread, I thought, why not put the collective knowledge of this forum, to work.
So far, the journey in this thread, has been great.
Mick.
It is not very PC these days because of the water usage, but a tap (faucet) vacuum aspirator pump works fine. But you have to clean the filter flask every time because that is the bit you want. In the lab it was just as often the material on the filter that was important.
