George Ravenscroft

George Ravenscroft (1632 - 7 June 1683) was an English businessman in the import/export and glass making trades. He is primarily known for his work in developing clear lead crystal glass (also known as flint glass) in England.

Personal life

Little is known about Ravenscroft’s personal life, character, or appearance, though his father described him in his will as a responsible family man and an astute businessmancite book
last = MacLeod
first = C.
title = Merchant and Glass Manufacturer. In: Oxford Dictionary of National Biography
year = 2004
publisher = Oxford University Press
location = Oxford] . He was born in 1632, the second of five sons of Roman Catholic parents who hid their true faith and lived outwardly as Anglicans, and he was baptized in Alconbury Weston, England, in April 1633. From 1643 to 1651 Ravenscroft attended the English College in Douai, France to train for the priesthood, but he dropped out before finishing his training and returned to London by 1666. Ravenscroft’s whereabouts and activities between 1651 and 1666 are unclear, though it is certain that he lived in Venice, Italy for at least some of this time working as a merchant and possibly learning glassmaking techniques that he would later bring back to England. After settling into London and establishing a successful import/export business that made him wealthy, Ravenscroft married Hellen Appleby, from Yorkshire, England, in 1670 or 1671 and had three children with her. Ravenscroft died June 7, 1683 after suffering from “a palsy” and was buried in the Ravenscroft vault in the Church of St. John the Baptist in Chipping Barnet, England. Today in Chipping Barnet a school, a park, a garden, and a road are called Ravenscroft, suggesting the importance of the Ravenscroft family in the area at one time.

Early Career (1651-1666)

Although Ravenscroft’s movements in this time period are not well known, at some point he established a successful import/export business in Venice, Italy with two of his brothers, Francis and James.

Later Career (1666-1683)

Background

Ravenscroft moved to London by 1666 and continued working in the import/export business, trading goods such as currants, glass, and lace. There are differing accounts of Ravenscroft’s role in the invention and subsequent development of lead crystal glass. This much is generally accepted to be true: During the years Ravenscroft lived in Venice (sometime between 1651 and 1666) he was involved in the glass trade, not as a craftsman but as a merchant, so he knew and associated with glassmakers in Italy. By the time Ravenscroft moved back to England several glassmakers there had already started manufacturing glassware that attempted to mimic Italian cristallocite book
last = Klein
first = D.
last2 = Lloyd
first2 = W.
title = The History of Glass
year = 2000
publisher = Little, Brown
location = New York] , and Ravenscroft decided to start his own glass-making business while still running his import/export business.

Ravenscroft was likely the head and financier of his glassworks but not actively involved in the physical process of making the glass – that role was likely performed by one or more craftsmen in his employ such as Italians Signor da Costa or Vincenzo Pompeio or his English assistant Hawley Bishopp, who set up his own glassworks in the Savoy after Ravenscroft’s death. Ravenscroft’s glassworks produced mainly drinking glasses but also made some bowls and posset pots.

At this point the circumstances concerning Ravenscroft’s role in lead crystal manufacture becomes less clear, partly because records from the mid-17th century are incomplete but largely because Ravenscroft was secretive about his ingredients and processes to prevent competitors from copying him and to seal a deal with the London Glass Sellers’ Company, to which he gave exclusive rights to buy his creations at pre-determined prices.

There is some debate over how, when, and why Ravenscroft got the idea to use lead in the production of glass. Some believe that he accidentally discovered that adding lead to the glass mixture lent the final product special qualities while others believe that he learned the technique while living in Venicecite journal
last = MacLeod
first = C.
title = Accident or Design?: George Ravenscroft’s Patent and the Invention of Lead Crystal
journal = Technology and Culture
volume = 28
issue = 4
pages = 776–803
date = 1987
doi = 10.2307/3105182] . Whatever the origin of the idea, Ravenscroft believed that he had a unique product to offer the English market, so he applied for a patent in 1674 to establish his right to be sole manufacturer of lead crystal glass in England. He only produced lead crystal glass for a period of five years, disintegrating the business in 1679. His patent expired in 1681.

Ravenscroft’s Lead Crystal Glass

Ravenscroft’s glass works were set up in two locations, the primary facility being established in Savoy, London in 1673 and a secondary, temporary facility set up between 1674 and 1675 in Henley-on-Thames.

Early Ravenscroft glass (1674-1676) developed crizzling (gradual, unstoppable deterioration characterized by numerous cracks, making the glass look cloudy) quickly (within 1-2 years) because of some fault in the type or components of the glass-making mixture; excessive alkaline salts or insufficient amounts of lime, which acts as a stabilizer, have been suggested as possible causes. No early pieces are known to exist today.

The crizzling resulted in damage to the reputation of the company, and Ravenscroft and his team worked to fix the problem. Ravenscroft announced in 1676 that the crizzling problem had been resolved and that the new, improved glass vessels would bear a raven’s head seal to distinguish them from earlier, faulty pieces. A small number of glass vessels bearing the raven’s head seal exist today, some of which have crizzled and some of which have notcite journal
last = Charleston
first = R. J.
title = George Ravenscroft: New Light on the Development of His “Christalline Glasses.”
journal = Journal of Glass Studies
volume = 10
pages = 156–167
date = 1968] .

More pieces created by Ravenscroft may exist, but in the absence of the raven’s head seal, which he stopped using in about 1677cite journal
last = Hildyard
first = R.
title = Glass Collecting in Britain: The Taste for the Earliest English Lead Glass
journal = The Burlington Magazine
volume = 136
issue = 1094
pages = 303–307
date = 1994] , or any descriptions or drawings of his designs it is difficult to positively attribute particular pieces to him. Some pieces thought to strongly resemble Ravenscroft’s work bear an “S” seal; some have suggested that the “S” stands for “Savoy,” Ravenscroft’s main production facility, while others believe that the “S” stands for “Southwark,” indicating the South London glassworks of John Bowles and William Lillington.

The addition of lead oxide to the raw ingredients of glass resulted in a melted mixture that had a lower viscosity than ordinary glass, which had the advantage of being less likely to contain air bubbles but made it difficult to blow and made it particularly suitable for blowing into mouldscite book
last = Cuneaz
first = G.
last2 = Barovier
first2 = R. M.
last3 = Mentasti
first3 = R. B.
last4 = et.
first4 = al.
title = Glass Throughout Time: History and Technique of Glassmaking from the Ancient World to the Present
publisher = Skira International Corporation
location = Italy
date = 1994] . Lead glass also has a higher refractive index, making it appear sparkling, bright, and brilliant in light, and it “rings” when struck.

Legacy

It is not known why Ravenscroft decided to sever his ties with the London Glass Sellers’ Company and leave the glass-making business in 1679, but his style of lead crystal glass became fashionable in England and within 20 years of his patent some 100 glassmakers in England were producing lead crystal glass. Ravenscroft did not “invent” lead crystal glass, as others had already discovered the advantages of adding lead oxide to glass, but he did improve the process. Less than a dozen of Ravenscroft’s pieces are known to exist (see table below), and the “robust simplicity” of his designs is still admired.

ee also

*Glass
*Lead glass
*Crystal glass
*Glass production

References