OK call me 'Anal retentive' but the paper air filters, are of such good quality, that I vacuum all the crap out. Blow through from inside to a outside with an air line.
I then wash them by hand in warm soapy water. Rinse under the tap from inside to outside. Leave to drain then stick it in the airing cupboard. When dry I place in a box as the replacement for next filter change. I run two filters like this, for many years.

Ian