Four layers of satin mask (no cotton)

Mid 2021 update:  High thread count cotton and/or multi-layer polyester satin isn't a good choice for high filtration masks. They're not breathable enough at mid filtration performance. And additional layering to get to hight filtration still only decreases breathability further. With that they get hot and uncomfortable as well as giving your chest muscles a good workout.

 Satin is polyester - not to be confused with sateen (cotton) or silk (from an insect).

Here's six layers of satin that is from cut up sheets from Amazon. I've been using the same source for six months now for mask making. Whereas I'd coupled this satin with high-thread count cotton before, this is a mask that's not doing that. 

Goal: mask that is high filtration and washable. 

Constraint: a mask that doesn't require stiffeners / retainers / ribs to force the 3D cupping away from nostrils/lips. 

This still RagMaskMax: https://cv-masks.github.io/ragmask-max.html. What's new is that steps 1, 2 & 3 are skipped. Also that step 6 is four layers of satin folded before sewing evenly spaced lines back and forth parallel to the fold lines.  That's going to make the multi-layer mask have some stiffness - satin is very floaty and a single layer will quite easily pull into your nostrils on a breath in.

Mask above the old 750 thread count cotton and satin mask (one layer of each). Mask below the one I've just made - 4 layers of satin only:

Inside of new mask:

Verdict: it doesn't pull into your nostrils/lips as you draw a breath. Meaning it meets its design goal. As I gazed at myself in the mirror using it, I could see the fabric flex some as it did pull in a little. Someone you were talking to as you wear this mask might wonder why it does that, but frankly lots of masks do that these days. It you were super self conscious you might still wish for a stiffer design.

Filtration?

Not tested specifically, but calculated as between 6 layers of satin and 2 layers of satin:

This is from Zach's test data from May. Konda's data (also from May) would indicate that filtration is better, but I can't compare the satin I have to the satin he tested so I'm sharing the more conservative results here : around 85% protection for aerosols.