Old 78 rpm records were pressed from a resin made by insects
Between 1921 and 1928, Europe's record industry used 18,000 tons of shellac to press 260 million discs. That resin comes from a tiny female insect, the lac bug, which leaves it on tree branches in India and Thailand, and somewhere between 50,000 and 300,000 bugs are needed for each kilogram.
The bug, Kerria lacca, feeds on sap and constantly secretes resin, forming tunnel-like tubes along the branches that are sometimes wrongly called cocoons. Swarms can reach 150 insects per square inch, and the name probably echoes lakh, the Indian word for 100,000. Harvesters scrape the crust from the bark, then heat it in long canvas tubes so the melted resin seeps through, leaving bark and bugs behind. It dries into sheets that are broken into flakes, which users dissolve in alcohol.
Written records of shellac go back 3,000 years, and the Mahabharata describes a whole palace coated with it. Spanish painters were binding pigments with it by 1220, and trade with India made shellac seals common across Europe from the seventeenth century. In the nineteenth century it pushed aside oil and wax to become the West's leading wood finish, until nitrocellulose lacquer took over in the 1920s and 1930s.
Its range of uses was remarkable. With a melting point of 75 degrees Celsius, it acts as a natural thermoplastic and was moulded into picture frames, inkwells and even dentures. It stiffened the toes of ballet pointe shoes, protected Braille sheets from wear, and glued dinosaur bones until about the mid-1960s. In the 1930s roughly half of all shellac went into gramophone records, and it stayed in use for some children's records into the 1970s.
Woodworkers still value it. It dries to a high gloss, resists ultraviolet light and does not darken with age, and a scratch can be mended with a fresh coat that fuses with the layers beneath. Strength is measured in pounds of flakes per gallon of alcohol, with most ready-mixed cans at a 3-pound cut. Once dissolved it keeps for only about a year; a sample that stays tacky on glass after roughly 15 minutes has gone off.
Source: Shellac
