Masks help protect the person wearing them from inhaling micro-organisms such as the SARS-CoV-2 virus which causes COVID-19 disease. They also protect other people from the wearer's own germs. Surgical masks are basically intended to protect others (e.g. patients with open wounds) from the wearer's (e.g. surgeon's) germs. Respirator masks are designed to protect the wearer. Some respirator masks (such as the one pictured, right) have a valve making it easier to breathe out, which give little or no protection to others.
This is all pretty academic since surgical masks and respirators are in short supply world-wide due to the global COVID-19 pandemic, and supplies should be reserved for medical workers and others at high risk. Could home-made / DIY masks serve a useful role? A study found that home-made masks could be better than nothing. and the US CDC recommends that people should make and wear their own, and they give some plans for making masks, with and without sewing.
I decided to make mine (before coming across the CDC page) and tried various plans I found online but found them either too complicated or incomprehensible, and ended up with the design shown below, which I'm pretty happy with. But do see the CDC page for even simpler designs, as well as advice on use, washing etc.
I start with a rough square about 30cm (1 foot in old money) of material. Mine is like cotton sheet (it was actually thin curtain material which this time last year we were cutting into bandanas and block-printing with the extinction symbol for the April Rebellion) and I just cut a cm or so into the side and rip it to size: this saves laboriously marking and cutting a square, and thanks to the weave of the material it comes out square automatically.
To make it easier to sew I ironed down a centimetre (or so) wide section at the edges for hems before sewing them.
I used PVC-sleeved solid wire from some scrap 2.5mm T&E electrical cable for the nosewire, and doubled it for extra stiffness. Thinner wire doubled up more times should work. My nosepieces are about 7cm long (i.e. 14cm of wire folded double).
Su had some of this funky purple elastic lying around. I cut a 23cm length for the top strap and 19cm for the bottom.
Having sewn hems on two sides of the square (with the nosewire trapped in the middle of one hem) I fold the material to bring the two hemmed edges together. Then I fold the hems of the sides in together (so they will be invisible from outside the mask), and sew the strips of elastic in between the hems. The longer strip goes at the top (open side) of the mask.
* But seriously: these are not FFP3/N95s masks; they don't make you invulnerable to the virus. Compensate for
risk compensation! A DIY mask helps reduce the risks to ourselves and to other people especially in situations where we can't avoid being close to others, such as in shops or on public transport. But we should still go shopping or travelling as infrequently as possible, and get in and out of shops as quickly as possible. See the CDC's page for washing and use info, etc.*
* But don't get it mixed up with this page.
Here's a piece in Scientific American about masks and how to use them.