We are repeatedly being contacted with questions like “how long does your developer lasts” or “how long does the developer lasts after I opened the bottle”.
So we felt it is time to write a little paper about it.
Photochemisry is organic chemistry, and can somehow be compared to the expiration dates on a food product. It slowly degrades from super fresh and awesome to very well usable, well usable, quite well usable, usable, still usable, probably still usable, possibly gone bad to “dead”. Your yogurt does not turn bad at midnight of the day which is printed on the cap, and you may possibly enjoy it even weeks later.
If we were forced to give a guarantee date, we would need to be very conservative or tolerant.
“After purchase please use up our developers within 6 months”
“Our developer XY lasts in an unopened bottle between 6 months and 100 years”.
Does this help? Not really….
You need to find out yourself, if you do not want to constantly buy new chemicals.
• PRODUCTION DATE
Make a judgement how long has the product been stored on the shelve of the dealer before it got into your hands.
If you shop with large suppliers, you can assume that every standard product has been in the store for not very long. Fotoimpex shares a warehouse with ADOX, getting the freshest out-of-production items. A smaller local shop probably stores the chemistry a bit longer.
In general, we expect our products to arrive with the customer within 12 months after the production date at the latest.
ADOX bottles show the production date (not the keeping date) next to the barcode (except for very small units, where there is no space to print this information) to make this easy and transparent to our customers.
From the date of purchase, we expect our products to keep at least another 12 months in the unopened, cold and dark stored original bottle (making it 24 months in total).
• STORAGE CONDITIONS
Ideally, chemistry is stored in a cool and dry, dark place at around 8°C. This is cold enough to slow down chemical processes and warm enough to keep the usually highly saturated dilutions from crystalizing. When crystals form, essential substances are missing, and deterioration is accelerated. This is why photo chemistry may not be frozen. If freezing happened during transport and crystals were formed, re-dissolve your developer as quickly as possible by gently heating and gently shaking it. Check the color. It should still be quite clear. If brown sludge (tar-like) remains, do not use this developer anymore.
• BOTTLE QUALITY
The gas diffusion capability of your bottles affects the keeping properties. ADOX is using very expensive and highly gas-blocking bottles since about 2015. These bottles have the shape of PE-HD bottles, but they are as good as PET bottles. Regular PE-HD bottles are inferior and no longer used by ADOX for chemistry which is subject to oxidization.
In general, you can check if your bottle is made from:
Glass = the best option. Cat.A
PET or ADOX PE/PA = very good. Cat. A
PE-HD or other materials which are non-blocking = inferior for developers. Cat B
In a Cat. A bottle with at least 500ml of liquid the outlined keeping properties of 24 months after production should be expected.
• SURFACE-TO-VOLUME RATIO
The larger the surface of a bottle in relation to the content inside, the more important is the oxygen blocking capacity of the bottle. Small units have a by far inferior relation than large containers. A large container has thicker walls, which protect better. So, the smaller the unit, the lower the keeping time until it spoils. 5-liter buckets are the best in this respect. On the other hand, we sell some very small units, so they are used up quickly after opening. This counter-compensates the keeping problems.
The most important question is “how much oxygen has gotten into the bottle”. The oxygen reacts and uses up parts of the buffering system. When the buffer is exhausted, it keeps on reacting with the developing substances, and the developer starts deteriorating.
• The amount of times the bottle has been opened – the more, the worse.
• Protective gas or glass marbles to push the air out of the bottle. Plastic bottles can be squeezed within limits to press out the air, especially when very little has been used.
• How fresh was my developer when I first opened it? The younger the better.
• How much concentrate is left? (An almost full bottle keeps very well, a puddle on the bottom does not).
• CRYSTALLIZATION. If large crystals have formed and are clearly seen at the bottle bottom, it is not a good sign.
• COLOR SHIFT. The crystals fallout will be often accompanied by a noticeable darkening of the developer. Most developers are bad when they have turned darker than tea. However, comparisons should be made to the original color right after mixing. Rodinal may come dark brown from the beginning, and still works perfectly even when it has the color of coffee. XT-3, on the other hand, should not be used when even a slight color change has occurred (in relation to it´s color right after mixing). Ascorbic acid paper developers turn dark yellow to reddish, but often still work. It really depends on the individual developer and this can only be one factor out of many to base a judgment on.
If the developer looks good, but you still have doubts, you can perform a test. The only problem is: this only works if you have made an identical test when your developer was still OK.
1. Make a mix of the developer like you would to process a film. In daylight and in a transparent container, drop in a snippet of film (for example, the tongue sticking out of a 35mm cartridge).
2. Note the time it takes to completely blacken the film.
3. Repeat this test with seasoned developer. If the time is off by more than 15%, do not use the developer anymore. If it is less than 15%, extend the developing time accordingly (5%, 10%..)
With paper developers it is not that critical. You see when the developer is bad. Most paper developers should develop to full Dmax in light within less than 60 seconds. If it takes longer, blacks do not come fully and/or the color shifts to brown, the developer has gone bad.
• Do not buy a large amount of chemistry if you do not intend to use it. Buy only as much as you need. ADOX is offering several package sizes in most products to make it easy to buy the right amount of chemistry. We even have 100ml “baby”bottles.
• Consider storing chemistry in glass bottles, if it was sold in a PE-HD bottle.
• Use protective gas, squeeze the bottle or throw glass marbles into glass bottles to completely remove all air trapped above the developer.
• Keep the cap/thread clean from dried developer. Dead developer (brown powder) works like a catalyst and speeds up the degrading of the remaining fresh developer. Avoid bottles with horizontal rings for this reason.
• We do not recommend the bellows-shaped folding bottles. It is tricky to clean inside the bellows, where old developer might still remain. But most importantly, the soft plastic lets oxygen pass through. These bottles are OK to keep paper developer from one day to the next, but to not for long-term storage.
• Keep the developer in the original bottle, if it is a PE/PA or PET bottle.
• Do not use any food bottles. We had a hospital call us one day for someone who filled a Coca-Cola bottle with Rodinal and drank it! Always mark chemical bottles properly!
• Last but not least: This paper is on DEVELOPERS. A stop bath is not as sensitive and can be kept in original, even not highest-quality, bottles.