RagMask Max as a pattern for arbitrary fabrics and toward higher filtration
OK so I've a year of experience with the RagMask Max pattern.
You can pick a high TPI fabric (like 600+ TPI per Konda et al *), but without retainer / boning to force cupping, it is going to be a suffocation device as it collapse onto your nostrils/lips with each breath in.
You can choose a fabric that's finer like satin**. Note that it is so fine that it needs strategies to retain the 3D cupping for the same collapse reason. I found "corn rows" to be good for that. Aaron Collins found the filtration was 55% for six payers of satin:
With a test particle size of 63nm (smaller than the viron itself), the 6-layer mask is 66% protective after the first wash & dry (55% before that). When Aaron did a second test with the edges pressed onto his face, the filtration was the same. Meaning for him at least the RagMask Max as supplied was a good fit.
Aaron's video - https://www.youtube.com/watch?v=2IM_5DH_aUw&t=3260s
Konda et al also talked up satin.
You can choose a naturally stiffer fabric like spunpond NWPP. This supports layering without corn rows or a retainer/boning, and keeps breathability.
What RagMask Max is really really good for;
- Multiple layers - you are limited by your presser foot.
- Quick to sew - 6 - 12 mins per mask depending on materials.