Life Cycle of Sea Glass

By Anita St. Denis

Sand originates from rocks or broken pieces of marine life such as shells, fish bones, sand dollars, snails, corals, or seaweed. Sand also can come from pieces of bottles and dishes discarded into the sea.

Silica sand is added to soda ash, limestone, and recycled glass cullet and heated up to 2860°F in a furnace. When molten it can be crafted into glass objects such as bottles and tableware.

the life cycle of sea glass from sand to glass to sand
the lifecycle of sea glass from glass back to sand

The gemlike colors of bottles and dishes are derived from adding carefully selected elements. For example, iron added to the molten glass results in a blueish green color, cadmium with sulfur results in a deep yellow color, and copper oxide produces a turquoise color.

Before recycling, bottles and tableware were thrown away in dumps, often near rivers, lakes, and coastlines. Over time, rough wave action washing the glass against sand and stone begins to smooth the glass.

Sea glass can take 40 to 100 years to acquire its texture and shape. Over the years, the fragments of glass become smaller, the edges become smooth, and the surface takes on a frosted look.

If left to the elements, over time the sea glass pieces become smaller and smaller until they are once again grains of sand.

This article appeared in the Beachcombing Volume 38 September/October 2023.

Clockwise from top: Sand (Photo Melon/ Glassblowing (wjarek/ Antique bottles, rough sea glass, smooth sea glass, and tiny sea glass (Anita St. Denis).

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