Oxidation is a natural aging process for stained glass. When oxidation occurs buff with a cotton or micro fiber towel and a carnauba based wax. Stained glass contains lead-wash your hands after handling. Hang your stained glass with a screw in wood. Window suction cups tend to fail with the change in the weather and time. If using fishing wire, be sure to change it periodically to avoid uv deterioration. Enjoy!