As well as being the title of an evocative novel by US author Anita Shreve, sea glass is a favourite amongst the beachcombing fraternity. Don’t think broken bottles lobbed onto the beach by drunks, but instead, imagine small frosted nuggets in many colours, transformed by the tumbling action of the sea from our rubbish.
The east coast of northern England is probably the best location to find beautiful examples, but here in the southwest, the east beach at Lyme Regis isn’t bad. From Victorian times till the 1960s, the town rubbish dump was on top of the cliffs, but landslips and coastal erosion since have brought a lot of debris from the tip onto the beach. As a consequence, it’s a magnet for people looking for rusty and, indeed, glassy treasures. Whole bottles – some improbably distorted – can be prised from the thick grey clay, and down on the foreshore, broken sea glass in varying stages of smoothness can be found in profusion (not to mention old car chassis and engine parts, smoothing irons, electrical switchgear, sparkplugs, springs, boilers and tanks, broken china and much else recording the habits of past generations. People obviously ate a lot of fish and meat paste, and used a lot of cold cream!).
I enjoy collecting the glass for the variety of colours and shapes. Green and clear are the commonest, followed by brown. Blue is fairly common (Milk of Magnesia!) but all the smooth bits are prized, leaving mainly rough chips and smaller pieces to find. I’ve found just a handful of red/orange pieces – probably from car lights, and one luminous yellow one, plus a few scraps of cranberry and fluorescent green uranium glass. Milky white from cold cream jars is another occasional find, as is opalescent semi-clear glass.
But being a nerd as well as an artist, my favourite finds are the lavender ones. These are often hefty pieces, and vary from very pale greyish-pink to quite deep lavender (which strangely enough looks grey by artificial light). I was puzzled by the colour until I found various references on the web. Cheap soda-lime glass at the turn of the 20th Century was doctored with small amounts of manganese oxide to counteract the iron content in the glass that made it green. A hundred years later, the action of UV in sunlight has changed this to sodium permanganate which is purple in colour. (As anyone who remembers redox reactions from O-level chemistry will know!)
As a graduate geologist, I was familiar with the metamorphic processes of heat and pressure on rocks over millions of years. So I was interested to see what only a few tens of years could apparently do to glass objects buried in clay. Flattened bottles and slag-like contorted glass full of inclusions are common on the beach. This is called “bonfire glass” by the beachcombing fraternity, though I am not convinced it always had to burn; pressure may have been enough.