Cloth version of Craig Turner's DIY mask - take 2

This is is a second attempt at making a cloth version of Craig Turner's high-spec mask. First version detailed here. And some tweaks to the retainer in a third post today on the same mask design.

Mask features:

• Four layers of satin.
• Attempt to stiffen (via zip-tie) the vertical seam that is on the outside now with bias binding tape
• Narrower retainer, fixed with four button-stitches (may well come out in the wash)

The seam is better on the inside, perhaps. Informally the two mask I made earlier (two layers of satin) and this one (four layers) feel equally breathable.

Note that I didn't zig-zag the edge. The satin threads are so fine that it's a mess within seconds if you don't sort them out. I've satin bias binding tape arriving in the next few days, so we'll see f that's quicker/better.  I'm not going to finish this mask, but four and six layers of satin are the "high filtration" holy grail.