I bought the Ilford paper developer described here. However, despite having it stored in a dark environment, it turned brown quickly after about 10 days.
Can I ask how you are storing/using the developer, and how much developer is in the bottle? For example do you carry the opened bottle of developer around with you, and extract the required amount of developer (2ml for 1:9 in a 20ml syringe) as and when required, and then top with 18ml of water?
The change in colour is caused by oxidation, which will be increased with agitation of the bottle. You can of course still use it, but the amount of development will be reduced, and given the relatively small volume of the syringes would be a risk.
Personally, I split my 1 ltr dev into 2 x 500ml bottles, to keep one fresh whilst I use the other. Those don't travel anywhere. I also make up a working solution 1 ltr 1:9 and keep that in concertina bottle, so that I can reduce the air space down (that would be perfect for the main developer, but the smallest I found was 1ltr collapsing to 500ml), this lasts me months - that's 50 shots before I have to worry about airspace under 500ml, and would dispose of it if it showed more than light yellowing. I also transfer enough diluted developer to the Pinsta transport bottles which hold 100ml - 5 shots worth of additional solution.
If I have travel anywhere, like a holiday, then I take my diluted solution in the concertina, and the Pinsta travel bottle. My main dev bottle, doesn't go anywhere.
If the remaining 450ml changed colour in 10 days, without any movement, I'd be inclined to still use it.
An indication that it's exhausted would be the inability to reach maximum density - black, upon development. Increasing the development time, and/or reducing the dilution might help.
Can I ask how you are storing/using the developer, and how much developer is in the bottle? For example do you carry the opened bottle of developer around with you, and extract the required amount of developer (2ml for 1:9 in a 20ml syringe) as and when required, and then top with 18ml of water?
The change in colour is caused by oxidation, which will be increased with agitation of the bottle. You can of course still use it, but the amount of development will be reduced, and given the relatively small volume of the syringes would be a risk.
Personally, I split my 1 ltr dev into 2 x 500ml bottles, to keep one fresh whilst I use the other. Those don't travel anywhere. I also make up a working solution 1 ltr 1:9 and keep that in concertina bottle, so that I can reduce the air space down (that would be perfect for the main developer, but the smallest I found was 1ltr collapsing to 500ml), this lasts me months - that's 50 shots before I have to worry about airspace under 500ml, and would dispose of it if it showed more than light yellowing. I also transfer enough diluted developer to the Pinsta transport bottles which hold 100ml - 5 shots worth of additional solution.
If I have travel anywhere, like a holiday, then I take my diluted solution in the concertina, and the Pinsta travel bottle. My main dev bottle, doesn't go anywhere.