Chapped lips

And just WHY does licking chapped lips make them worse?

I’m curious about this too because the popular reason offered is that the evaporation of the saliva causes dryness. What doesn’t make sense to me is that while evaporation of water from inside the skin would cause dryness I’m not sure by what mechanism having external water applied would cause more dryness by evaporation. Perhaps a biophysicist can chime in on that one. I thought a more plausible explanation might be that undiluted enymes left on the skin might irritate the mucous membranes or the act of licking physically removes what little natural oils your lips would produce to act as a barrier against evaporation.