I think it's important to point out that Collins is doing on-face quantitative testing, while Armbrust is only testing the material of the mask. They're not re

I think it's important to point out that Collins is doing on-face quantitative testing, while Armbrust is only testing the material of the mask. They're not really comparable - a loose surgical mask may be made of good materials and filter well in Armbrust's test, but it's not even worth including in Collins' list because it doesn't seal against the face and won't ever get more than around 60% efficiency. Collins does often test again with a "mask brace" which is a rubber loop that seals that mask against your face, and can achieve similar numbers to Armbrust. Of course, since everyone has different faces, Collins' testing becomes less valuable the more different your face is than his. But he also has advice for getting a decent face seal.