Cast Bronze and aluminum plaques are known for their durability and offer timeless beauty. Over time, even with regular cleaning bronze will “Patina” turning the metal surface a greenish or dark brown color. This is part of the natural oxidizing process that occurs when copper is exposed to the elements. Our polyurethane finishes and clear coats will slow the aging process, but eventually all plaques will begin to oxidize. Cast aluminum plaques will also corrode/oxidize or over time. Aluminum plaques tend to darken and a chalky white oxidation can appear when exposed to salt or certain chemicals. Many companies promote “Rust-Free” aluminum or bronze plaques, which is true because the materials are absent of iron (rust is the name given for the oxidation process on iron). While some customers love the natural “aged” look that results from the oxidation process, others prefer the crisp factory finish on their cast bronze or aluminum plaque. We offer a variety of refurbish and restoration services for cast metal plaques; call us for additional details and prices. Port City uses the highest quality paints and finishing techniques available in the industry, view our Paint & Finishes Section for additional information.