There are many types of glass used in creating mosaics and in this section of Shards of Knowledge we review the most popular in-depth. Some glass materials are made specifically for the purpose of mosaic making and others are upcycled to create something new from what otherwise might be cast away. From the breathtaking mosaics created in Byzantine times to contemporary fine artworks glasses are hugely popular as a mosaic material. Glass is a surprisingly durable material, it can withstand freeze-thaw cycles (because it is vitrified).
Glass is made from natural and abundant raw materials (sand, soda ash and limestone) that are melted at very high temperatures and carefully cooled through a process of annealing. Stained Glass, Smalti and other colored glasses are created by adding specific metal oxides. Glass can be transparent, semi-transparent or opaque. The reflective nature of glass makes it an appealing material for mosaics.
Glass occurs in nature in a few forms such as volcanic obsidian and fulgurites. Glass making dates back as far as 3600 BC where it first appeared as beads. Over the centuries that followed craftsman harnessed its formability to create durable objects such as vessels, elaborate decorative objects, optical glass and so much more. Its durability makes it an excellent mosaic material. During the 4th century glass began to make an appearance in churches across Italy and is still today the main material used in creating mosaics.
