Yes, to both questions. but, to ensure good adhesion, glossy surfaces must first be washed clean and then sanded to allow the paint to “grip” the surface. Gloss alkyd paints that are exposed to harsh weather conditions have a tendency to “chalk” – that is , the old paint film develops a faded, powdery substance on the surface. So it’s best to wash off any excessive chalk prior to applying an acrylic topcoat. When painting bare surfaces, use an appropriate primer before applying the topcoat. This will ensure the best adhesion and long-term durability.