Experts and BHG readers answer.
How can I choose the best type of paint for a high-moisture area?
Unfortunately, any type of paint will ultimately fail in a high-moisture area such as a shower. To achieve the longest-lasting finish, sand to bare wood and apply an oil-based primer followed by two coats of alkyd paint. If and when you replace the window, vinyl would be a better choice than wood because vinyl never needs to be painted.