: I used an asbestos cartridge(the pink ones) when sanding the
: epoxy. Do you think this was a safe enough choice. Also it has never neen
: a matter of comfort as I believe in safety, but as you are aware it is one
: more expense that if not needed... I'm talking about the black ones that
: you are referring to. Thanks for a reasonable response.

The pink cartridges are for dust only, and they probably work OK for sanding. Nevertheless the black ones aren't that much more expensive, and they last for quite a while if treated properly. They work forever against dust, just use the cheap disposable prefilters as well. When not in use, seal the mask, cartridges and all, inside a gallon-size ziplock bag. As for when to change it, put it on, open a can of solvent (MEK, xylene, lacquer thinner, toluene, MIBK, etc.) or even ammonia or vinegar. If you can smell it through the mask, swap out the filters. Given the short times that they will be used in building one boat, one set should last for several boats if stored like this. When I did epoxy floors all day every day for a living, mine lasted for weeks.