[TheFeldhamster]

Since the Expedit is made from laminated chipboard you do NOT need to paint it. Actually, most paint will not even really stick to laminated chipboard unless you sand it down first. Laminated chipboard is waterproof enough to withstand a bit of hamsterurine and disinfectant and over here, it's the number one recommended material to build diy cages from.

What you DO need to do is to seal any edges so that no fluids can get to any raw edges. For this, aquarium silicone is the material of choice. It's not that hard to work with, makes all the edges water-proof and is non-toxic. Be sure to use *aquarium* silicone, though, NOT bathroom silicone or other around the house silicones (because those contain fungizides).

I am not sure about the new high-gloss Expedits, though, their finish looked a bit more like just foil instead of the real, hard laminate of the "normal" colors to me in the store.