I hesitate to admit that I have dried them in a food dehydrator once they have absorbed too much moisture from the air.  They do not strike as well as before they got damp but most did work.  I now keep all matches in Ziploc bags so I don’t have to worry about that so much.  They were very old when I dried them out but still worked.  I have since replaced most of them as 15-year-old matches are getting long in the tooth for me.     
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When the wolf attacks he will find that some who run with the flock are not sheep!