Latest research on fabric masks says to use 2 layers of heavy weight quilter's cotton (180 count or higher). If using lesser density, add internal layer of flannel. No knits - the holes in them are too large. This would include t shirt fabric. Suggests using fabric strips rather than elastic so it is adjustable for the person using it. Only use mask when completely dry. Moisture provides a growing atmosphere for virus.Continue to social distance - this kind of mask only helps others not get anything from the mask wearer and does not prevent the wearer from getting anything.