The can was originally 40F, but is now 74F after being brought out to a room. After 2 hours, the can is 58F. 74-58 = 16. There is a difference of sixteen degrees after two hours, or a difference of eight degrees per hour.
If the vanish is best used at 68F, the can is currently 10 degrees too low.
8 degrees an hour means that even after an hour, the can will still be two degrees too low.
2 is 1/4 of 8. An hour is 60 minutes. 1/4 of an hour is 15 minutes. An hour plus 15 minutes = 75 minutes.
The answer: you must wait 75 minutes before you use the vanish for best results.
