The polypropylene can be cleaned as recommended by Health Canada: a hot wash with detergent. It can be washed with the mask or separately. It should not be tumble dried: it should be removed from the mask and hung or laid flat to dry before reinserting. Do not iron it: it is plastic and will melt

Recommended material

For community mask manufacture, we suggest using industry-grade spunbond polypropylene. A three-layer pleated mask using cotton outer layers and a fully-integrated middle layer of 68 gsm (two ounces per square yard) polypropylene. The mask is quite structured but comfortable, because of the cotton, and completely washable. (Catherine Clase)

The material can be integrated as a middle layer when masks are being made.

Alternatively, a rectangle of spunbond polypropylene can be inserted between the two outer layers of a cloth mask. The material does not fray easily. If using two layers of polypropylene, we suggest folding the material in half and sewing it together with a simple stitch or an overlock, to make a washable filter.