Originally Posted by matt167
I open a package of cartridges, use them until there about 1/2 used up and throw them out, get another package of cartridges out of the cabinet and use them.. when I painted my '51 Chevy, I used 6 sets fresh right out of the packages.. that included 2 coats of epoxy primer tho
Some people may think you are just wasting them but I remember back at one of our mine safety training classes we were shown a chart for activated carbon cartridges that showed declining effectiveness with use. The effectiveness of these things starts to decline as soon as you start using them but depending on the concentrations of the contaminate they remain within a safety margin for a given amount of time. What this means is that even though they may still be within mandated safety limits you can still lessen your exposure by changing the filters well before their saturation point, probably not really necessary but for piece of mind and extra security it does make a difference. I will open a pack and use them once then toss them, not recommending everyone do this but I feel safer doing it.