My wood bed is painted with Rustoleum satin black, and it holds up well...However, it lives in a garage, and seldom sees rain. Remember, paints that get hard and are designed for metal will not take much stretching. Wood, by nature, expands and contracts with temperature and moisture changes. I used enamel on a park bench, and after a few years, it cracked and the wood rotted where the moisture got in.
