think it all depends on what kind of wood it is. Silicone is a nice sealant to use for stuff that will be in constant contact with water. I used silicone as the sealant for my background that I made of styrofoam which was covered in grout then painted with acrylic. Since the enclosure will be constantly humid and being misted i covered the whole thing in a layer of clear silicone. The one downside (to some it isn't) with using silicone is that it leaves you piece looking shiny. To combat this some sprinkle sand over the silicone before it dries. I sprinkled black sand on mine to break up the shine, though the shine makes it look like its wet so its not all that bad