George Ravenscroft - 17th Century Pioneer in Glass

by Deborah Swift

I love the fact that writing historical fiction takes me up all sorts of byways. Whilst researching for my new book set in the mid 17th Century, I wondered what sort of glasses they might have drunk from, and whether by then, it would still be pewter or horn. When did glass make an appearance for the everyday person? Not early enough for my book apparently, for though glass for windows and chunky simple cups had been made in England since the 13th Century, the impurities in the glass made it brittle and unsuitable for fine tableware. Fine glass was imported, usually from Venice. But in the later 17th Century a new method was developed by George Ravenscroft - a method that would mean England could produce its own glass to rival that of the Italians.

Anglo-Venetian glass with Dutch engraving - National Gallery of Victoria

George Ravenscroft was a trader in goods such as currants, glass, and lace. During the years he was trading, and before he arrived in London in 1666, he lived in Venice. Being involved in the glass trade, he was able to observe the method used by glassmakers in Italy, but soon came up with his own version of glass manufacture, using a mixture which was produced with a high lead content. Experiments he made between 1674 and 1676 gave a brilliant transparent and hard-wearing heavy glass which we now know as 'lead crystal.'

Secret Formula

The circumstances surrounding Ravenscroft’s role in the invention of lead crystal are not very clear. 17th Century records of the manufacturing process are incomplete, but moreover, Ravenscroft was rather secretive about his ingredients and processes. He was wary, as one might expect, of competitors copying him.

It is thought he had assistance from Sir Robert Plot FRS, who had the idea of using flints from Oxfordshire river beds. In Murano, Italy, where the best glass of the era came from, very expensive white flints from the River Po were used. Historians cannot agree on how Ravenscroft was inspired to use lead in the production of glass. Was it an accident, or had he pinched the idea of adding lead oxides to the glass from the glassmakers of Venice? To add to the confusion, an Italian book about glass making - L'Arte Vetraria, written by Antonio Neri in 1612, was translated into English by Christopher Merrett in 1662. Here's a quotation from the book describing lead glass when molten:

"This sort of glass, lead glass, is so runny that were it not cooled, and taken up by turning to wind a gather, it would be impossible to work. It is so runny that it would not even hold onto the punty, because it is as loose as soup. This arises out of the lead calx causes it to become very fluid."

Crizzling

Adding lead oxide to the glass made it less viscous than ordinary glass when heated. Because of this, it could be worked for longer without re-heating. The early glass Ravenscroft made was subject to developing a crackled surface known as crizzling, (what a lovely word!) caused by too much potash in the mix. But by1676 Ravenscroft had improved the glass, making lead glass, which contained a higher quantity of lead oxide, thus preventing crizzling. Lead glass has a higher refraction that previous English glass, making it sparkle, and ring like a bell if you gently strike the edge.

A well-crizzled decanter from the V&A 

Unique Glass Patent
Ravenscroft was granted a patent from King Charles II in 1674 to be the sole manufacturer of lead crystal in England. His prices were one shilling for a claret glass, rising to one shilling and eight pence for the heavier beer glass. Ale at this time was a strong drink that required a bowl of four fluid ounces, whereas a wine glass held only two. Because of Ravenscroft's invention, the prices of glasses dropped steeply until by the end of the century it was six shillings a dozen.

A George Ravenscroft glass, also in the V&A

Ravenscroft's was a short but glittering career that lasted only five years,as he closed his manufacturing business in Henley-on-Thames in 1679. The following year he joined the Vauxhall glassworks, working with the company until his death in 1683. By the late seventeenth century, the trade in Venetian glass was in serious decline, whilst in England there was a boom in glass manufacture. The English couldn't get enough of this light, clear glass and it was produced in ever-growing quantities to meet burgeoning demand at home and abroad.

Read more about it from Glass Historian David C Watts

Sources:
English Drinking Glasses - L M Bickerton
History of Glass - Dan Klein and Ward Lloyd

Find my books at www.deborahswift.com
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Trade in the 17th Century - The Tallow Chandler

by Deborah Swift

Matthias Storm c.1640 Old Woman with a Candle

I was at a great loss for candles; so that as soon as ever it was dark, which was generally by seven o'clock, I was obliged to go to bed ……… The only remedy I had was, that when I had killed a goat, I saved the tallow, and with a little dish of clay, which I baked in the sun, to which I added a wick of some oakum, I made me a lamp; and this gave me light, though not a clear steady light like a candle."

The Life and Strange Surprising Adventures of Robinson Crusoe, 1719

Light has always been a symbol for move out of ignorance and into the light of knowledge. As long as we can manufacture and control light, then we are no longer bound by the seasons, or forced to work from sunrise to sunset. Light gives us extra time for work and play, and the time to create during the hours free from chores or work.

The candle was one of the earliest forms of artificial light, and in the period in which I write, most candles were tallow. I need to continually think of this whenever I write a night-time scene, or a winter scene. We take the availability of good light so much for granted.

The Stink of Tallow 
Tallow was cheap animal fat, usually the waste material from meat - hence often sheep or bullock fat.

The tallow was prepared by first chopping the fat into small pieces and then boiling it up in a large copper to detach the muscle or membrane from the fat. The resultant mush was pressed to extract the 'juice', or tallow, and the remains or 'greaves' fed to the dogs or pigs, and even to the geese that were being fattened up for market.To produce a pure light, the chandler must wrestle with dead animal carcasses, and the associated smell and mess. For this reason, chandlery was perceived as a very low class trade, and the chandlers premises were often located near the tanneries and slaughterhouses, and close to a river with access to water. The process reminds me that for every 'light' there is the often invisible 'dark'.

'A woman reading by Candle-light' by Frans van Mieris the elder,
c.1665; black chalk on vellum.

Fir candles, made of a long thin splinter of fir, were commonly used in Scotland, and a fir candle holder was known as a "puirman"(poorman). But tallow candles were the common household candle in early England, and by the 13th century, candle-making had become a guild craft in England and France, controlled by ancient City Livery Companies. The Tallow Chandlers Company, one of the London Guilds, sill exists. It was formed in about 1300 to regulate and manage candle-making. Over the next 150 years they expanded in membership and influence, until King Edward IV granted them a coat of arms in 1456.

In rural areas, where no Livery Company existed, chandlers would sometimes go from house to house with their moulds, making candles from the kitchen fats saved for that purpose, or in smaller towns they made and sold their own candles from a shop. Candle-making was usually done in winter by a householder, as livestock was generally slaughtered around Martinmas (November 11th) to save the expense of over-wintering them. Tallow candles could be made for you in your own home with your own saved drippings by an itinerant tallow chandler (tallow chandlers and wax chandlers had separate guilds, and jealously guarded their products).

Candles, especially tallow ones, were kept in a wooden or metal box hung on the wall in order to protect them from vermin, as being animal fat, mice regarded them as food. Being away from the fire also prevented the candles wilting and bending in heat.

A candle box of 1680

Holy Beeswax
Unlike animal-based tallow, beeswax burned pure and cleanly, without producing a smoky flame. It also had a pleasant sweet smell rather than the foul, acrid odor of tallow. However,  it took an entire honeycomb's worth of beeswax to make one 4" candle, so it was very expensive. Beeswax candles were widely used for church ceremonies. The beeswax itself had a religious significance in 17th Century England. One story is that bees were absent from the Garden of Eden and so escaped Eve's sin. Another is that medieval monks thought that bees reproduced by immaculate conception, like the Virgin Mary, and so the beeswax of a church candle came to signify purity.

The Revolutionary Art of Plaiting a Wick
The absorbency and efficiency of a wick depended on the number of individual strands. Adding or subtracting a few extra strands of animal hair or hemp fibre made the difference between a candle that burned well, or one that guttered or dripped. The wicks were made from twisted threads of flax, cotton, or hemp, and trimming the wick to get rid of candle "snuffs" was essential to keeping your candle burning well, or it would flare and smoke. I often imagine my characters having to trim the wick in the middle of conversations, or tackling writing a letter.

The best wicks were invented later in the 19th century, and revolutionised the candle. They were plaited so they curled as they burned to ensure that the tip burnt off during use so they didn't have to be continually trimmed, thus ensuring you could carry out your task uninterrupted. To achieve this curl, the plait or braid of a wick was woven asymmetrically, with a few extra strands in one of the threads. After being cut to length, the wicks were dipped in molten wax so that one end was stiff enough to poke through the hole at the bottom of the mould, and then the moulds were filled.

Wooden & Pewter Candle Mould

The Fall of Tallow

The tallow chandler's fortunes declined at the end of the 17th century. New materials, such as spermacetti (from whale blubber) and paraffin wax, replaced tallow. Then in the late 19th Century gas lighting arrived, twelve times as bright as a candle, only to be replaced by electricity twenty years later. These eras are comparatively short, when you think that we had many hundreds of years where most of our light was by the dim smoky haze of tallow candles.

More about lighting? Lucy Worsley has a post about domestic lighting here.

Thank you for reading. Find my latest book, Pleasing Mr Pepys, here.

Sources:

Images from Wikicommons

The Social History of Lighting - William O'Dea

Restoration London - Liza Pickard

At Day's Close: A History of Nighttime - Roger Ekirch

http://clanntartan.sitesneakpeek.com/manual/lighting.html
https://www.tallowchandlers.org

https://www.periodoakantiques.co.uk