system
Given the following post, respond as if you're commenting on Reddit:
human
eli5: Why isn't water the most effective Chapstick?

How come liquid water isn't the most efficient moisturizer? after all, it is 100% moisture, but when I take a sip of water my lips don't heal as quickly as they do when I apply Chapstick.
gpt
Because the point is the "moisture" will still evaporate if there isn't a fatty humectant layer to prevent it from doing so. The chapstick or Vaseline or whatever else you use provides that barrier which therefore locks moisture in speeding up healing.