Varnish it! I love drawing/painting and have made some really nice paintings on wood. I wanted to keep them safe from ruin, so my dad suggested putting varnish on them. We got some and applied a thin layer to them. I've had some of them for like 5 years now and they still look new. You might want to try that. You can also buy clear protective spray paint that will serve the same purpose........it might even be better.