Effetre glass (Italian: [ˌɛffeˈtrɛ], Italian F3, abbreviated form of fratelli tre, "three brothers"), once known as Moretti glass, is a kind of glass used in lampworking. It is considered a medium-soft glass and is popular because of its wide range of colors and the ease with which it is molded and shaped when hot. Genuine Effetre glass is made in Italy by the Effetre International Company on the island of Murano. It has a working temperature of 1,733 °F (945 °C) and a coefficient of expansion value of 104. Effetre is a variety of soda-lime glass.
- Ray, Susan; Pearce, Richard (2003). The Art & Soul of Glass Beads: 17 Bead Artists Share Their Inspiration & Methods. Iola, Wisconsin: Krause. p. 9. ISBN 978-0-87349-565-3. Retrieved 15 July 2011.
- Codina, Charles (2005). The New Jewelry: Contemporary Materials & Techniques. Lark. p. 50. ISBN 9781579907341.
- Mehaffey, Louise (2011) . Glass Beads: Tips, Tools, and Techniques for Learning the Craft. Mechanicsburg, PA: Stackpole books. p. 14. ISBN 978-0-8117-0814-2.