Tray Processing Chemical Lifespan
 

Sorry if this has been covered before but I couldn't find it in the search.

I process my prints in 3 trays as I get a lot of joy watching the print appear. Now I have been mixing fresh chemicals for each darkroom session which lasts 4 to 6 hours.

Now my question is does the fixer and stop go off in that time or can I poor them back into bottles (Removing the air) to use again? If I can use them again how many times should I do this?

Thanks
David

With developer it is better to make fresh every time, with stop use the indicator type and simply botttle it after the session and keep sing it untill it changes color, or if using clear acetic acid type when it no longer smells of viniger then chuck it with fixer it depends upon how many prints and whether ypu are using FB paper or RC, I use fb paper and the two bath method of fixing, and the fixer is botteled after use, I gusee on average 10 prints in a 3 or 4 hour session, and use the 2 trays of 1 liter of fixer for 2 sessions, then I discard fixer bath 1, and fixer bath 2, which is the fresh fixer, becomes fixer bath 1, with fresh fixer mixed at 1/9 for bath 2, which for me works, I would say that for RC paper if you produce around 10 to 16 prints per session then the fixer should be fine for 2 sessions, at least, with RC prints that is what I found, I always made 1 liter of fixer/stop/developer, and print to 9x12 1/2, You used to be able to get fixer test kits to tell you whether the fixer was good or not, but I don't know if they are still around,
Richard

Chemical life
 

This is a question that could go on and on and on and...…..

Personally with the developer (I always use Ilford Multigrade) if I work in the evening I can usually still get a good print the following morning, but after that I can only say the results are not very good. An open tray allows the surface of the developer to absorb more oxygen which will allow it to go off more quickly.

Others may say differently, but developer is the cheaper of the processing when compared to paper. You will probably start to loose the depth of the blacks. 100cc of concentrate will suffice for one nights printing with no difficulty. (Up to 12 x16 dish).

As for fixer and stop bath they are pretty stable and will not go off readily. (or as quickly) With stop bath they usually have an indicator when they are just about shot. Also the 'odour free' version that uses citric acid to stop or neutralise the developer action and can over time form a coating of hairy mould. I don't think this does any damage or effectiveness of the bath, except the mould can stick to the emulsion of the print and if not noticed can be the very devil to get rid of afterwards.

The other thing that affects all three is evaporation of the water part of the chemicals. Especially if you use a dish heater. You have to ensure the quantities remain almost constant. You could try marking the inside of a dish where 1 litre comes up to if it drops it is easy to top it up.

With the stop and fix you could try replenishment very much the same as I do for colour printing. For every 80sq inches of paper add 100cc of each which will keep them active for a long time. It may even work a time with the developer (Diluted form) but I prefer to ditch the old and start again.

Thanks

I always mix new developer as tried it the next day and the results were poor. I use Ilford stop and fix so will give it a go if reusing


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I always reuse stop and fixer. Ilfostop has the advantage of being both low odour (citric acid based) and has an indicator dye. Other similar stop baths are available.

Fixer requires more serious consideration. You can keep a track of the area of paper used (usually in terms of the number of 8x10 prints or equivalent area) which is invariably written in the fixer instructions somewhere.

My favourite method is to keep track of how long it takes to clear a piece of film. With newly mixed fixer at working temperature, drop a small piece of film into some of the fixer and and see how long it takes to clear as you swish it gently around (it will go from black to transparent). I mark this time on the bottle I am going to keep the fixer in. Keep a few off-cuts of the same film (the cut off leader from 35mm film is a handy source if you develop your own b&w film).

Each time you want to reuse the fixer, do the same film test. In my case, I make up new fixer when the clearing time has increased by 50% - others suggest when it doubles (100%) but I use film-strength fixer for 75s with fibre paper which relies on good strength fixer.

If you bottle the developer after a session it should keep until the next day, or possibly longer. The number of prints through it is important. If you only managed to do a couple, you should be able to keep the developer in a bottle for a further session. If it has been used for several prints, a fresh batch is a better idea. The developer instruction sheet will tell you the capacity per litre.
Alex.


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On the subject of developer: I have in the past floated a layer of cling-film on top of the developer in the tray overnight. Of course, you need to be able to safely leave the trays in place and removing the clingfilm can be messy if the trays are not in a sink but it would still be fine if care is taken not to spill the dripping developer everywhere... I mostly use my Nova slotty-thing these days and leave the developer in there for a couple of weeks with cling-film plus the tubes that come with the Nova making a better seal than the tubes themselves.

I take it Bob that cling film ensured the developer was good for the next night's developing?

If it was then it sounds like a cheap solution for a 24 hour extension

The only way to increase developer life in trays that I have read about is to use the one stocked by the Photographer's Formulary in the U.S. called Liquidol

This is the famous paper developer devised apparently by Ron Mowrey a long time Kodak chemist whose death was announced
on Photrio about a week ago

Mike

Yes, the idea is that the cling-film keeps the air off the developer - it's not a long-term option as it is probably too thin to be especially good at that job, but seemed to work fine overnight. It may also depend on the developer of course. I used Agfa Neutol WA which was a pretty good keeper. Luckily, Adox revived it when Afga stopped making it so I am still using it in my slotty-thing today.

Sorry to hear about Ron Mowrey - I recall many of his posts when it was APUG.

Cling Film.
 

Lik Bob, I too use clingfilm but not on B&W. I should have mentioned that if I leave it overnight to continue the following day, I pour the developer back into a 2 litre bottle I have kept for that purpose.

Plastic is not a good insulator preventing oxidisation but it is a very good way of preventing the water content from evaporating. I have used it for very nearly 30 years with colour developer in a Nova Processor. (As well as the tubular lids.)What I find happens is, as the chemicals cool, a slight vacuum is created when the chemicals cool and loose volume. The clingfilm must be wrapped around the top and pressed into the corners to make a good seal.