Is there a color change to indicate whether I have had my chemicals too long? Do they discolour when they have lost potency?
The only chemical that I would be concerned about aging would be developer. If it is a bottle that has never been opened and has been stored in a cool dark room, I would guess that shelf life should be a year or more. If the bottle has been opened and has any amount of air in it then the developer will oxidize fairly rapidly and be useful for only a month or two. If it has oxidized it will turn brownish in color, as compared to a relatively clear new solution. If on the other hand, you have poured out some of the concentrated developer and then squeezed the air out of the plastic bottle before recapping it, then the concentrate should last much longer before oxidizing. Slightly oxidized paper developer is quite alright to use, but slightly oxidized film developer will give a change in contrast to the finished negative, so I can’t recommend using oxidized film developer. Concentrated fixer and stop bath have a very long life and I would not be too concerned about either of these chemica
