Does it have an oil finish on it?
If there are larger areas of bare or open grain and you,plan on taking it out in the weather, you might want to wipe on a thin coat of Birchwood Casey Tru Oil and then wipe off the excess.

One coat will seal the wood and will not leave you with a shiny plastic looking finish.

You can also remove it with denatured alcohol, so if you want to thin down the look of the new finish, just give it a wiping with a soft lint free cloth like denim.