From the Manufacturer:
Beautiful, color-saturated, acid-free, transparent inks. They have an alcohol base which makes them indelible and moisture-resistant when dry, and allows you to use them on almost any surface as long as it s clean and oil free. Highly versatile, Pinata can be used in a variety of applications, including rubber stamping, fine art, fiber art and scrap booking. It can also be used in calligraphy, faux finishing techniques, airbrush applications, wood and leather staining and more. The colors silver and rich gold are formulated with real metal pigments and are super opaque.