How to Create Green Patina on Copper Crafts For a Vintage Look
A patina can be defined as a thin layer of colored oxidation which occurs on some metals over time, such as the green or gray rust on copper or bronze. The romantic name is verdigris: Think of crusty old copper roofs or a weathered bronze statue. When making crafts using natural copper, adding a green patina can create the old-world appearance of a vintage artifact.
Here are five techniques to add patina to natural copper - and one outrageous shortcut. But before you start: Clean the copper to remove any grease or coating. With these recipes, be very careful with chemicals or ammonia: wear chemical gloves and work in a ventilated area. The solutions can be applied to the copper by spray, brush or sponge. The patina usually appears after the copper has dried completely. It may take several applications and results can vary wildly.
Okay, ready? The first four recipes are for the purists who must do everything from scratch.
Apply a mild solution of 20% salammoniac (found at metal supply stores) dissolved in 80% distilled water.
Apply a solution of 50% Dormant Spray (Lime-Sulfur Fungicide found at garden supply stores) and 50% distilled water.
Apply a solution of salt (10%), ammonium chloride (10%), liquid ammonia cleaner (20%), and wine vinegar (60%). Ammonium chloride can be purchased from chemical suppliers.
Put the copper in a plastic or glass air-tight container. Cover the copper with a light layer of salt and put an open container of ammonia with it. Seal the container overnight.
Purchase a copper patina solution at your craft store and follow the directions. This always works.
And one outrageous shortcut:
Sponge or brush on an imitation patina using blue, green and gray craft paints. Use your best antiquing techniques of dabbing and wiping. It is much faster and much more controllable than chemical mixtures.