i have a bottle of quick fix 4.0, i bought it about six months ago, do you think it is still good?
If you have any doubts about its condition, you can always test the batch at home. Do a Google search for Drug Adulteration Test Kits. These are essentially the same kits the labs use when checking the creatinine, specific gravity, pH, etc... If the batch tests good at home, its ready for the lab Nazis.
The shelf life of the 'Fix is 18-24 months. The shelf life begins on the manufacturing date, which is printed on the enclosed directions sheet, disguised under an alphanumeric batch code.
(Example: F10C-07 = Oct 2007)

Batches that are bad can be exchanged for a replacement at Spectrum Labs, even if it was purchased at a headshop.