How long can I keep a developer

[JJChan]

Our local shop still has plenty of D76 powder.
I'm still new to developing film learnt from YouTube and stuff on the net only so probably doing things poorly.

Can I make a solution and keep it stored for a while or does it go off? Is it better to stick with concentrated solution (eg Ilford DDx) and mix amounts when I need it?
I'm probably developing a couple of rolls a month at the most.

TIA

JJ

[Ann]

I always preferred to make fresh solutions if I wasn't going to process for a while — except in the case of those solutions which are designed to be re-generated (such as the Bleach in colour film processing).

If you decide to keep and replenish for each batch, keep a record of the amount of film which has been processed and make sure that your storage bottles are filled to the rim and sealed tightly. Glass marbles added to the bottle can be useful in that case!

[pluton]

Exposure to/contact with air, and to a lesser extent light, is the enemy.  The dry powder in the original factory packaging should last longer than mixed liquid---assuming that however each is stored, air space in the container is absolutely minimized.
One strategy with liquids is to make the large amount (typically 1 gallon, ≈4 liters) per the directions, but instead of storing it in a single large bottle, store it is smaller containers that hold enough for one developing session, thereby avoiding the air space that occurs when the volume of developer in a large container is drawn down over time.
Concentrated liquids suffer the from same vulnerability to air exposure as dilute liquids. Dark glass is considered better than plastic. Store in the dark in any case. 

[JJChan]

Thank you Ann and Keith - will take these all onboard

[Jacques]

I used to use a series of concertina bottles, once the required solutions were removed press gently on the top of the open bottle until the remaining liquid is near the top and then fix the top on thereby minimising the air in the bottle. When processing B&W I always looked for the higher dilution option as in 1 part dev 3 parts water then discard the solution once processing is complete, it takes a little longer processing time but each film will be processed in the same strength ? Solution without having to make notes of how many films have been processed with the stock solution and working out if any adjustments to processing time are needed.

[David H. Hartman]

If buying old stock Kodak chemicals inspect the bags of dry chemicals for creases that might indicate pinhole air leaks. The powered chemicals inside will turn brown and I would not use it.

I recommend mixing a gallon or four liters of stock D-76 developer. I stored the stock D-76 in 1 quart brown glass bottles but filled them into the neck for about 1 liter of stock D76 per bottle. The exact quantity isn't important only consistency. If memory serves me Kodak recommended a shelf life of three months in full, tightly stopped, glass bottles. Please double check and if the developer looks brownish dump it. My storage was consistently 70*F, 21*C.These bottles were probably regent grade with cone shaped seals. They originally contained chemicals for offset printer. 

An advantage for glass bottles is one may clean them thoroughly using plain water with a little washed plaster or play box sand.

For developing I used 1 part stock D76 with 2 parts water. This gave me finer grain than 1:1 and less harsh grain than 1:3. I used one shot developing at 70*F / 21*C. I recommend pulled developing for Tri-X (is it still made?) of EI 200 and if needed pushing the film with selenium toning.

Finally I recommend printing with a diffusion or dicronic color enlarging head for spot free, scratch free prints.

I know this is a late post but I hope those scanning for information may find this in the future.

Dave Hartman