I have a similar question, and didn't want to create a thread for the same topic.

I would like to incorporate a large piece of wood in my terrarium, pretty much simulating a tree. So I've got a punky log cut to fit, (split almost down the center) with the flat side against the glass, (will be anchored with suction cups) and the bark exposed to the terrarium. It's about 6" thick.

Do baking times need to be increased for thicker pieces of wood? I want to make sure I get the entire inside of the log sterilized, but would like to avoid burning the bark.