Creating a green or blue patina on metals like copper, bronze, or brass is a popular technique for achieving an aged, artistic finish. One of the most common methods is using a chemical solution, such as ammonia or vinegar, to accelerate oxidation. For a green patina, a mixture of ammonia and salt can be applied, while a blue patina often requires copper sulfate or liver of sulfur. Natural aging is another approach, where exposure to moisture and air over time develops a patina organically. Heat application can also enhance the process, creating unique color variations. Whether for art, jewelry, or architectural elements, these techniques offer versatile ways to achieve stunning, weathered effects.