Silk is far better then cotton. It's cooler and lighter.
"Neu-sur-ba said: You must see any affliction as an enemy and attack it as soon as it arises in your mind. Otherwise, if you acquiesce when it first appears, and then nurture it with improper thoughts, you will have no way to defeat it, and it will conquer you in the end.”
-Lam Rim Chen Mo eng v01 pg. 348 tib pg. 275