Gourds used in making mate cups are a natural product and contain dried pulp. The curing process helps clean the gourd--and inhibit mold growth. To cure your gourd: Rinse it with plain warm water and remove any loose pieces of the dried gourd with a spoon. Do not remove the inner hard "stem" from the flower end of the interior of the gourd or this could result in a greater likelihood of leaking. Drain. Add fresh or spent yerba tea with more warm water and let sit for an entire day. Repeat these steps again, drain the yerba fluid, let dry completely, it helps to put a paper towel to help absorb the moisture. Your cup should be ready to go after one day of curing, yet some can go for two or three consecutive days. Your gourd then will be infused with flavor and ready to use.