Building a playgym?

[Mydoona]

I have already built a playgym but am now building a bigger BETTER Playgym for my lovies (now they will have 3) and was wondering if there is something I can treat the pine wood I am using to keep it clean?
the other one I built gets poop on it and I clean it off with hot water but I am scared the wood might swell up and warp and ruin my playgym....thanks.:confused:

[thebubbleking]

what about pine sap? i know it seals in water and is safe to nibble...just an idea :)