system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How come bars of soap feel slippery on the skin initially, but soon afterward leave your skin feeling coarse/rough?
gpt
Soap itself is slippery. But it also dissolves fat. Your skin secretes fat for protection which does also make it soft and smooth. The soap can dissolve this fat and get it to rinse away which leaves your skin bare. This makes it feel rough and dry until the fat layer reforms. A major difference between body soap and cleaning agents is how well they dissolve fat. You want body soap to just clean off dirt and bacteria but leave most of the fat alone.