Oil Paint Question

[temptress.livejournal.com]

The boxes cattereia posted reminded me that I have big plans to paint boxes myself (they're sitting unfinished on top of the bookshelf). I am going to latex/acrylic the base coat and oil paint on the motif...how do I protect them after that? What varnish (or something else?) would protect the oil paint but not make them tacky to touch (since I want these to be usable and touchable!).

Thanks for any advice!