Bill Jamieson
Member
The instructions suggest that a half full bottle should be OK for 6 months. I have a bottle opened in early March this year which is still about 75% full, having been stored in cool conditions over the intervening seven and a half months. Given the hassle these days of obtaining photographic supplies I'm keen to use it - the concentrate doesn't appear to be discoloured at all but I'm uncertain as to whether or not this is a reliable indicator that the developer has not gone 'off'.
Bill
Bill