Patina is the naturally occurring oxidation of metals over time, creating a darkening or discoloration, depending on the type of metal. In stained glass work, it refers to any chemical used to create discoloration or darkening on metals.

In the copper foil technique, darkening the metal makes the shiny solder and copper foil blend into a single dull matte surface and allows the glass itself stand out more. In lead came work, patina makes the soldered connections between cames less noticeable.

Patina is made with very harsh and harmful chemicals, so it is important to handle and store patinas with care. Keep in mind if you order online that most patinas can't be shipped by air, so they will require slower ground shipment. Pricing runs from $4 to $6 for an 8 oz. bottle. There are also kits that combine the most popular types into a single package. One 8 oz. bottle should last for along time.