All of our face masks have 3 layers = 2 layers of linen/cotton/both in between 1 layer of synthetic non-woven interfacing. This middle layer acts as a sewn in washable filter that cannot be removed.
Our masks can be machine washed to a maximum temperature of 60degreesc. Do not tumble-dry, and do not dry clean them. A warm iron can be used to smooth them out after a wash, but be careful!