Expiry Dates

[writerkit]

How rigid is the expiry date on a KN95? I'm realizing that it is possible the reason Bona Fide Masks was having a sale has to do with the age of the stock-- the ones I just ordered were manufactured in April 2022 with a listed shelf-life of three years. If I'm not opening the package, how firm is that?

Comments

[squirrelitude]

I don't have a direct answer, but I recall that N95s (and presumably most N-type masks) work partially via electrostatic attraction of particles to the fibers. Some of this is electret materials, which are permanent electric fields (that can be damaged by liquids), and some of this is being just charged up at the factory by some kind of high-voltage device. I suspect that the expiration would largely be driven by leakage of that charge-up.

[kathmandu]

SmartAirFilters* has a blog entry on N95 expiration dates, saying the straps and ability to stay on tend to expire before the filtration capability, as long as it was stored within design limits.

I would suspect KN95s are essentially the same material/technology, so similar expiration behavior.

*They've been a reliable source on filtration materials since the pandemic started.