(b 1632 or 1633; d 7 June 1683). English glassmaker. His early life was spent as a merchant dealing in glass in London and Venice. In 1673 he set up a glasshouse at the Savoy Palace, on the Strand in London, where he produced a ‘crystalline’ glass, for which he obtained a seven-year patent in 1674. Later the same year Ravenscroft became the official glassmaker to the Worshipful Company of Glass Sellers of London. A research establishment was provided at Henley-on-Thames, Oxon, and Ravenscroft's entire production was sold through the company. The early glass suffered from a crackled surface known as crizzling, which was caused by an excess of potash. In 1676 Ravenscroft developed lead glass, which contained a higher quantity of lead oxide, thus reducing the effects of crizzling. The following year Ravenscroft was allowed to mark his glass with the Raven's Head seal. The lead-glass formula was perfected by 1681, and products made by Ravenscroft include jugs and goblets, the latter with hollow stems decorated with raspberry prunts. The new glass was heavier but more light-refractive than contemporary Venetian soda glass and was the perfect glass for cutting. The successful production of English lead glass created a large and prosperous industry. Within 20 years over 100 glasshouses were producing lead glass, which laid the foundation for the success of England's 18th-century glass industry. In 1678 Ravenscroft retired from Henley-on-Thames, where he was succeeded by his brother Francis Ravenscroft and Hawley Bishopp (fl 1676-85), the latter of whom took over the Savoy glasshouse in 1682.
From The Grove Encyclopedia of Decorative Arts in Oxford Reference.
Subjects: decorative arts, furniture, and industrial design.