As we all know by now, a respirator or mask is most useful for protection when you must be in close quarters with one or more people. That's why they are a must for healthcare workers and it looks like we'll be seeing more mask mandates for the general population. If you have to wear a mask in public, my feeling is it might as well be a good one. At the start of the Covid-19 epidemic, demand for masks worldwide outstripped production capacity and prices jumped to outrageous levels, prompting many of the handier types, like myself, to some...