You can waterproof your rattan benches and other types of rattan furniture through the use of a yacht varnish. Start by very lightly sanding down your rattan furniture with fine sandpaper; the idea isn’t to remove much of your rattan’s surface—you just want to give the varnish something better to stick to! Then, paint on 3 coats of a clear yacht varnish. Dry the varnish thoroughly over a few days, and then your rattan benches should be water-resistant.