This blog post was commissioned by Quba Sails.
Walking along the seashore, it’s impossible not to be drawn to the soft glimmer of sea glass. Incongruous and yet somehow ‘right’ against the pebbles and sand, the wave-washed colours and appealingly frosted texture of these small gems can make hunting for them a truly addictive beach pastime.
A product of mankind and nature combined, sea glass begins as glassware that has been discarded into the sea. In the not-so-distant past it was common practice to throw broken and unwanted items overboard as a means of quick (and thoughtless) disposal. Until the advent of plastics, glass was used more widely than it is now, particularly for packaging and containers; bottles and jars, tableware, traditional glass fishing weights and even windows ended up in the sea when their working lives were over. Washed gradually over the seabed and in towards the shore, each larger piece of glass is broken and re-broken into smaller pieces, and the cut edges are slowly worn smooth, their sharpness eroded.
The natural ‘tumbling’ that occurs in the pounding waves of the shoreline continues this smoothing process, and produces many different shapes of sea glass. On rocky shorelines, the glass may become trapped between rocks, and only one edge exposed to erosion; this produces angular shapes. The glass that is washed up on beaches in sandy areas tends to be more rounded, having been more evenly tumbled along the sand. Generally, the higher the PH value of the water, the faster the glass will become smooth, but it can take up to ten years in a constant surf environment for glass to become ‘proper’ sea glass.
A perfect piece of sea glass has no shiny spots, no sharp edges and an opaque, frosted appearance. Caused by long-term exposure to sea water, this tactile frosting results from a sort of etching on the surface of the glass. Specifically, the soda and lime component of the glass is leached out into the salt water, leaving a pitted surface behind. Each pit glimmers softly because of the tiny crystals that are formed when the lime and soda combine with other elements on the surface of the glass. This effect is almost impossible to duplicate artificially, although it is possible to buy cheap ‘craft glass’ that resembles sea glass. This is made by putting broken glass into a rock tumbler or dipping it in acid.
Perhaps the most fascinating part of searching for sea glass is that it is rare to find two pieces of exactly the same shade. Each colour provides its own clues about the history of the glass and its original use. The colours most commonly found are clear (opaque), green and brown; these pieces are likely to have originated from ordinary glass, such as beer bottles, household jars or windows. Within the same palette, however, there are many further variants; glass in shades of sea foam, olive green, aqua or golden amber may once have been part of medicine, bleach or spirits bottles, or cosmetic jars. Rarer colours include ice blue, purple, opaque white (from milk glass), grey, pink and teal (often from Mateus wine bottles), as well as cobalt or cornflower blue, which was frequently used for poison bottles. Yellow, red and orange sea glass are all extremely rare, originating from sources such as car tail lights, dinnerware or nautical lights; orange is thought to be the rarest colour, occurring once in about every 10,000 pieces.
In some instances, a colour can also indicate great age. ‘Black’ sea glass – very dark olive green glass – is rare, and sometimes antique. Black glass was used in the eighteenth century to make bottles for gin, beer, wine and medicine, and for liquids subject to light damage. The glass was reinforced during production by the addition of iron slag, and was usually thick and strong enough to survive long, often rough voyages; any bottles that broke were discarded upon landfall. Once emptied, the bottles were refilled for the return journey, and remained in use in this way for many years until they broke. The oldest pieces of this glass were hand-blown – this may be noted in just-visible trapped gas bubbles, impurities and irregularities in the sea glass. Due to its inherent strength it is not unusual to find larger pieces of old black glass, some of which may have survived for centuries.
Although we can guess at the history behind each piece of sea glass, ultimately that story is lost to the sea. The simple pleasure of combing the shore for these tiny coloured ‘jewels’ remains, for many, one of the delights of a visit to the beach; it is also testament to the curiously transformative power of the ocean, returning our rubbish to us as treasure.
Sources:
En.wikipedia.org
www.bytheseajewelry.com
This blog post was commissioned by Quba Sails.
