Gluedevil Mounting Squares Are Perfect For Home Decoration Such As Mounting Pictures, Signs, Name Plates And House Numbers. Holds On Smooth, Non Porous Surfaces Like Tiles, Metal, Plastic, Glass, And Painted Walls. If Surfaces Are Coated With Silicone Oil, Please Remove To Achieve A Successful Bond. On Painted Surfaces Please Allow Fresh Paint 4 Weeks To Cure Before Application. On Porous Or Unpainted Surfaces, Please Seal Before Application.