Waxed Cotton. You probably have it and don’t even realize it.
Belstaff makes a lot of iconic jackets. They are cotton but they are waterproof thanks to a heavy coating of wax. Normally you have to either have your jacket rewaxed or go through a labor intensive process of doing it yourself.
Recently we found Nikwax on Amazon. This solution is cheaper and faster than Belstaff’s on a $35 can of wax.
So save yourself some time and money by keeping your waxed cotton jacket fresh and waterproof!