Mahogany is one of those open grained woods that absolutely require paste wood filler before any finish is applied. Failure to do so leaves the grain open despite the finish, and water will get through.
Paste wood filler stain is offered by Interlux and Pettit, and it is very easy to use. (Colors are usually light or dark red and light or dark brown for mahogany)
Once the wood is filled (and stained) proceed with whatever finish you choose. Use something with UV filters in it. If varnish, put at least ten coats on, rubbing it out with fine sandpaper or scotchbrite between them.
When your masterwork is complete, consider a canvas cover to protect it!
Last edited by Goodnewsboy; 03-04-2007 at 11:02 PM.