I've been using a small fire bowl with impunity on a painted wood deck.
Last time around, though, I kept the fire going for several hours and
the paint showed some localized discoloration.

I've now purchased a new fire bowl, about twice the capacity, and the
directions are pretty clear about not using it on a wood deck. I'm
planning to have larger fires, and wondering what I can use between the
bowl and the deck that might insulate the wood from the heat. Ideas?