I was wondering why wetting your lips eventually dries them out, and whether this occurs with other areas of skin. Does the water somehow mess with the skin’s ability to retain moisture, or maybe soften the skin, allowing more water to escape or something?
You have wiped off the oil on the lips. Lips are a high blood flow area and the natural oil (fat) in your blood keeps yours lips soft.
But plain water is pretty bad at removing oil, and it seems that even if you just splash water on your lips without wiping they get drier. Also, how does the oil get onto the surface (since there are no sebaceous glands)?
The wikipedia article on chapped lips says “the evaporation of the water in saliva saps moisture from them”, but why does it sap moisture? Why doesn’t the added water just evaporate, leaving exactly the same amount of moisture as before?
Isnt just a case of you are more aware of the dryness? you feel them going back to the moistness they were before you licked them… so you lick again?
Or perhaps you often lick them when they are already dry.
I touch my lips. They’re dry. They haven’t been bothering me at all, but they’re like dry cellophane to the touch.
I lick my lips.
I wait a while and touch them again. They’re as dry as before. (Can’t imagine how they’d be any drier.)
But now there’s an annoying tingling.
Don’t know if it’s psychological, if it’s caused by waking up neurons, or if it’s the dried saliva residue. But it ain’t related to moisture content.
When my brother was little, someone asked him if he could touch his tongue to his nose, he could. Somehow touching his tongue to his nose became a habit/nervous twitch so he did it regularly.
The tip of his nose became dry/cracked/chapped. So it would seem that for some reason, the added moisture from his tongue seemed to make it even drier.
I would guess it’s due to evaporation. When the water on your lips evaporates, it sucks the oil out of your lip skin. The same effect can happen to the rest of your skin, especially if you live in a dry climate and don’t use a moisturizer.
My WAG is that there are enzymes in your saliva that will irritate the surface of your lips (or nose in the case of Joey P’s brother).
I believe it could be because saliva isn’t pure water, and when it’s put on your lips, osmosis causes the pure water on the other side of the semi-permeable membranes (of your lip cells) to diffuse out.
Ok, there is definately no “pure water” on the inner side of the cell membrane. But, it’s still a good thought.
I think the idea was that it’s pure water that comes out via osmosis, leaving the cells with less water in them than usual.