Humidity proofing melamine cage

I am making melamine cages for my beardies. While I am at it I want to make my two bps both new cages. So, what would I need to use to humidity proof it? Some thick coats of polyurethane? Or is there something better?


~Emily

Melamine is already coated with a plasticy type cover on the tops and bottoms so it should pretty much already be humidity proof. :)