POR-15 POR 15 46004 Stirling Silver Top Coat - Top Coat over Quart SILVER is a permanent silver coating developed for application over painted and unpainted surfaces. Apply over POR-15 Rust Preventive Paint for the toughest, most permanent protection against rust and corrosion ever developed. SILVER is non-porous and will not crack, chip, or peel when properly applied according to directions. SILVER is not sensitive to ultra-violet light and may be exposed to sunlight without damaging consequences.