Sea Glass and History

by Ted Greiner

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Humans living near a coast have probably always thrown much of their garbage into the sea because that avoids it getting infested by rats and insects. Ships have long thrown theirs into the sea. Shipwrecks add to the burden we put on it. For its part, the sea gradually has destroyed the vast majority of it (except plastic, sadly), but it does not visibly destroy glass. Thus, similar to ruins of buildings, it fascinates us as nature’s way of interacting with what we humans do; with all the ambiguities that brings to mind. 

 

Much of our glass gets broken into smaller pieces and some ends up on beaches. Over decades, the sand, sea and sunlight gradually change its shape, surface texture, and often even its color. After spending several decades on a beach, glass no longer is shiny. It has a frosty texture. It no longer has sharp edges; they have been rounded off. Chemicals used in its manufacture change or leach out of it, sometimes changing its color. Similar processes occur with ceramic items, china, pottery, and even tiles and other building materials.

 

Each piece of this so-called sea glass has a history, a story behind it, often called it “provenance.” Most seaglass is white (from clear glass bottles, jars, and even windows), brown (beer bottles), or Kelly green (certain soda and beer bottles). A soft or foam green and various types of aqua are the default colors of much glass made from batch sand (due to its iron content), so after the chemicals it was treated with to make it clear leach out with time, much returns to this color. Old Coke bottle glass is usually this color. Before 1920, manganese was used in glass and sunlight can turn it to a lavender color or with selenium, which results in yellow or orange seaglass. Glass from the early 1900s, so-called depression glass, can eventually turn pink or peach colored. Glass from old medicine bottles or ink bottles can be cobalt or cornflower blue, dark aqua, or dark green. Unusual colors may come from car back lights (red, orange or yellow), electric insulators (black or dark purple), grey glass from old TV screens, and art glass of any color.

 

But the most fascinating seaglass found in Olinda is black glass. At least it looks black on the beach, so one mistakes it for a rock. Holding it up to the sun, we see it is actually a dark olive-green color usually. Ale/beer and liquor bottles were commonly kept in glass this color in the 1700s and 1800s. But some of it was kept in special bottles for a special use – this is very thick glass made for bottles that were to be kept on board a ship for a long time so that the rocking of the boat would not break it. Much of this that we found may in fact be the famous “pirate glass.” Black glass is much more common on Olinda beaches than in most regions of the world, inspiring thoughts of romantic-sounding possibilities such as the “Pirates of the Caribbean” ranging as far south as Recife; contraband slave traders who operated in Pernambuco in the 1830s and 1840s; or further back in history, the Dutch, who were heavily involved in trading while they made Olinda their occupied capital; and, even after they were expelled, Dutch privateers may have been active in the region.

 

Olinda beaches do not have much ceramic/china, but there are occasional pieces of what looks like old pottery. The most common finds are building materials. These range from pieces of brick, concrete, roof tiles, floor tiles, and wall tiles. They have quite different styles, suggesting they came from homes destroyed by erosion at different times historically. In 1909, the harbor in northern Recife was constructed and enlarged. This changed the patterns of water currents north of it, resulting in increased erosion in the Olinda area. This was quite severe by the 1930s, destroying many buildings near the beaches, particularly in the Milagres, Carmo, and Farol beach areas. Presumably this is the reason for the proliferation of building construction materials scattered at different levels in many Olinda beaches.