Two layers of material better than one for face masks

A report published by the American Chemical Society in ACS Nano that a combination of cotton with natural silk or chiffon can effectively filter out aerosol particles — if the fit is good.

One layer of a tightly woven cotton sheet, combined with two layers of polyester-spandex chiffon — a sheer fabric often used in evening gowns — filters out the most aerosol particles (80-99%, depending on particle size), with performance close to that of an N95 mask material. 

Substituting the chiffon with natural silk or flannel, or simply using a cotton quilt with cotton-polyester batting, produced similar results.

The researchers point out that tightly woven fabrics, such as cotton, can act as a mechanical barrier to particles.

Fabrics that hold a static charge, like certain types of chiffon and natural silk, serve as an electrostatic barrier. 


Source: https://www.acs.org/content/acs/en/pressroom/newsreleases/2020/april/the-best-material-for-homemade-face-masks-may-be-a-combination-of-two-fabrics.html

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