I bought a set of graduated ring mandrels to try sculpting clay rings on them.

The wood came finished with a varnish, which I didn't expect. I thought it would probably be oiled, the way that kitchen tools are.

The maker won't tell me what varnish was used, so I'm uncertain as to if I can safely bake in the over with these, or if I should be wrapping a bit of wax paper around the mandrels, so I can easily remove the ring from the mandrel before baking.

I was wondering if anybody would know if varnished wood is in general safe to bake at polymer clay over temperatures or if I shouldn't even try? I don't want to set anything on fire or end up releasing toxic fumes.

Much thanks for any advice y'all have!