I bought two of the attached column, gotta love craigslist! I want to put them outside with my Halloween display but I'm not sure what I should use to weather protect them. They are made out of plaster.
You can use a an exterior clear coat with UV protection. Rust-Oleum makes Varathane, a satin exterior clear in a spray can that's available at Home Depot. It comes in a blue can and is non yellowing.