Thanks for the question. We have the raw wood sealed with exterior sealer and then used a marine grade exterior paint. At least 3 finish coats of paint or more. Also the shade was a vinyl roller shade, in some cases II have used vinyl slat blinds or even a translucent acrylic.Hope this is helpful. Michele

Thank you for answering the question --- we have a tiny master bathroom in a 1924 house with the exact same fixture layout, but the window was sealed over with tile by the last owner. We are contemplating down-to-the-studs remodeling in the next five years and want to restore the window, so this advice is very useful.

I really appreciate that you asked and answered this question. I have a newly renovated bath with a similar set up. We used marine grade paint however will go the extra mile and try the vinyl slat blind.

Window sill , casing etc in sold surface, Frosted glass, excellent flashing . And Still try to avoid it if you can