I'd take a wild guess at a latex compound.
Condoms are made by dipping a Phallic mandrel into a liquid rubber solution when cured, the coating is rolled off.
I suspect the factory -workers are pretty slick in a domestic bedroom environment.
try youtube and googoo,rubber dipping and coating......
AFAIK, surgeons gloves are made the same way as are those red Vinyl coated cotton industrial gloves.