If you are thinking about sewing your own cloth face mask and are wondering what to make it from,
this information might help.
Researchers in the US from the Argonne National Laboratory and University of Chicago have tested
different fabrics and combinations of fabrics, to find out how well they filter out aerosol sized
The COVID-19 virus is smaller than the gaps in the weave in any fabric, but fortunately the virus
doesn’t fly through the air on its own. It hitches a ride on particles which can vary in size from water
droplets that you can see, down to aerosols which are as small as 1 micrometre. A micrometre is a
thousandth of a millimetre.
What the researchers found is that layers of more than one type of fabric is best, as fabrics can work
differently in how they filter. A fabric can work by blocking the aerosol particles physically, which is
called mechanical filtration, or by electrostatic filtration, where the particles are attracted to and
bind to the fibres of the fabric. Cotton is a good example of mechanical filtering and silk of
The best combinations they found?
A 600 thread per inch cotton layer (that’s a high-quality narrow weave fabric) combined with
a silk layer.
A 600 thread per inch cotton layer combined with a cotton polyester flannel layer
A 600 thread per inch cotton layer combined with a chiffon layer
And when you are sewing your mask, use a design that means there is little in the way of gaps. Fit is
as important as fabric selection. With no gaps in the fit, these fabric combinations will filter out more
than 80% of the aerosols which might be carrying the virus, which is as effective as a well-fitting N95