I have a pile of ceramic molds that are stored outside under a plastic tarp for the past 10 years.. although the tarp wore out over the years and it is exposed to the rain in the winter. There is some mildew on the molds. I am not sure if I can rescue the molds after getting wet and weathered. Any chance these still are good or should I throw them away?

When you keep the molds outside, what you need to watch out for is that mice and rats love to make their homes inside the mold. It provides a warm cozy place to make a nest. Rats transmit disease so be careful.