.nat. said "Sorry in advance if this sounds ignorant - I’ve only used the disposable masks thus far. I’m trying to decide between purchasing and sewing myself for reusable masks. Everything i’m finding on amazon uses sold separately disposable filters, which seems to defeat the purpose of going with reusable? Not sure if the point is to simply cover up or if I need to be looking for specific specs or filters or fabrics - are there ‘rules’ to this? Any info appreciated! "
Most masks that have filter pockets are optional. I have some with pockets and some without, and I never use a filter as I found it started to make it challenging to breathe.
The general idea of a mask with more layers will offer more protection - 2 is better than 1, 3 is better than 2. But cloth/reusable masks tend to get wet (which is good - it's doing it's job), so the filter also absorbs some of the dampness. You could also use a piece of cloth as a filter, which could then be washed and reused.