A customer just asked if they could or should varnish or oil their new raw wood Wycheproof boomerang. The raw wood Wycheproof boomerangs are completely untreated. This was my reply (it might help someone else!):

Hi, that's a tricky question! It won't harm it if you do varnish it. I think any varnish would protect the wood and make it look nicer. It would also add a tiny bit of weight (so it would fly a bit further). Wood oil is a nice idea (easy too). But to be honest, if you are throwing in dry conditions and the boomerang does not get wet then I would only varnish if you want to. Btw, some people paint them to make the more interesting and to help see them in flight.