Four layers of thinner satin - modified Ragmask

One layer of 400-thread cotton (from a sheet set from the supermarket) the edge of which folded over four layers of the thinner satin (from a sheet set). I've not iron this flat before sewing but ptobably shoud have done. Plenty of wasteful excess to cut off.

 

All sewn (no straps yet):

 

A close up of the edge of the retainer. See how I've tucket it under the cotton flap, but outside the previous sew line that fixed the five layers together (the first line sewn).

 

This is harder to breath through that the double thinkness thinner satin version but that's to be expected. It is easier to breath through than my FFP3 mask which was surprising. I have no idea about releative filtration capability.