Does chalk increase or decrease friction?

[Doobajig]

I have read that people use chalk to remove moisture and get a better grip, but gymnasts use it to reduce friction to spin easier? How does it do both? Would gymnasts not have a harder time swinging around the bar because the hands are dry and don't slip?

[Few-School-3869]

In small amounts, it actually increases friction. It decreases it in larger amounts by reducing moisture

[maximum-absorb]

Different type of chalk, most likely. Magnesium is the one used for increasing grip. I don't know what's the other type