I was SO excited when I found out Modge Podge makes an outdoor formula! It protects all your outside projects and works well over your moulds and transfers. Mod Podge Outdoor is a waterbase sealer, and its glue and finish lets you decoupage projects for the outdoors. Seal and protect wood, terra-cotta, slate, tin and more. Dries fast and clear to a satin finish. Cleans up easily with soap and water. Non-toxic and non-flammable. Store at room temperature. 
Conforms to ASTM D4236.