I don't think you can do it, with a log that small. By the time you split it into a stave (even in half), it doesn't leave you with much to work with. How much sapwood does the tree have? With ash, I use nothing but sapwood. If you do decide to try it, split the log, remove the bark, and then just seal the ends. I use a commecial log end sealer from Lee Valley Tools, but wood glue or shellac will also work.