Is it safe to burn a pillar candle on a terracotta saucer that's usually under a flower pot? Would we need to treat the saucer in any way? I'm wondering - since water soaks through a flower pot, would wax soak through the saucer as the candle melts. We want to use them for candlelight decorations at an event & there will be rocks or shells around the base of the pillar on the saucer. Thanks for any help.