Frit is a durable, temperature-resistant ink that is composed of glass and ceramic particles. The composition of frit helps the adhesion of the ink to the glass, which is tempered onto a substrate at high temperatures, thus making it more abrasion resistant.
Epoxy is a cost-effective, user-friendly ink that can be cured at low temperatures and shows good opacity. It is thinner, not as durable as frit. However, it can be used on thinner glass, as epoxy does not require tempering to adhere to glass.