[brianmquinn]

Thanks everyone. I flood my bottles with nitrogen so I'm sure I can get your recommendations to last.

If you use plastic bottles the oxygen from the air can diffuse slowly THROUGH the walls and caps of a plastic bottle. So flooding with nitrogen helps but you really need to use glass bottles if you want really long life. I have stored both Xtol and D72 and D76 in small glass bottles (330ml) for an age test and even 4 years later they are colorless and work as good as new.