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lead glass

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Frank:
Patent's at that time had more to do with Royal favour... who you know not what you know.

I would be more interested in the more recent research, just no time to track it down... any Glass Circle members?

KevinH:

--- Quote ---Makes me wonder what characteristics Ravenscroft's had that others lacked - why did he get so famous?
--- End quote ---
The list of Contemporary Records listed in Powell's book (see above) includes an entry:
--- Quote ---1674. Petition of George Ravenscroft to the King for patent for seven years for his invention of manufacturing a sort of crystalline glass ... ... The Attorney-General ... reported that Ravenscorft's glass was made of ingredients other than those used in other glass-houses in England and the invention may be of considerable use as the glasses made thereby equalise if not excel those imported from Venice ... S.P. Dom.
--- End quote ---
Also, from The Art of Glass (Nerri / Merrett ) (2006 printing by The Society of Glass Technology), page 3 gives a general insight with:
--- Quote ---... and a lead-containing glass suitable for making crystal vessels. This last-named development is usually ascribed to George Ravenscroft and the date of its realization as 1675.
--- End quote ---

Frank's point about patents in those days is important. They were not quite as we understand them now. And those granted to such as Clifford, Powlden, Tilston, and Ravenscroft were very likely for improvements on a generally known idea. Also, the meaning of "invention" as used in the 17th century was seemingly not as "tight" as many of us would prefer it to be these days!

The fact that Ravenscroft did get a seven year patent and certainly produced glass that successfully rivalled the Venetian products, at least in its stability, would seem to be the reason for his "fame".

But as mentioned before (some time ago) "glass of lead" is now known to have also been made in Holland and perhaps pre-dating Ravenscroft and the other English makers.

krsilber:
None of that really answers my question about what characteristics Ravenscroft's had that the previous ones didn't.  Stability?  Workability?  Clarity?  Durability?  Ravenscroft went down in history for prefecting lead glass somehow, producing a metal that revolutionized the industry.  Obviously he was building on a long history of its use in glass, but it seems like if those before him had produced an good formula for blown crystal, it would have spread earlier. 

There are a couple articles about Ravenscroft in The Glass Circle 2 (avail. for 10 GBP here, incidentally) - is that why you asked about members, Frank?  Or different reason?  I'm not familiar with the organization.

KevinH:
Sorry! I read the question as asking about a combination of "general characteristics together with the fame of Ravenscroft". I did not see it is a question of specifics of what the glass had that others did not, as I thought that point had been covered elsewhere and was known by most who had an interest in "glass of lead" ... the issue being that Ravenscroft's "difference" was mainly a progressive increase in red lead which gave rise to a more stable glass than had previously been obtained (as I tried to indicate with my comment, "... successfully rivalled the Venetian products, at least in its stability ...").

Amazingly, I had entirely forgotten about my first reading(s), a few years ago, of the articles about Ravenscroft in "The Glass Circle 2". Perhaps I just interpreted things as being "more technical" than in the general literature but not adding any new info in a general sense. I'll have to take another look at them soon. :)

Frank:
The author is a member of the glass circle and members may have contact detaielos...

   See Peter Francis, The Development of Lead Glass, Apollo February 2000, pages 47 to 53


Ravenscroft is regarded as the inventor due to repetition in glass books that did not look deeper, just like Edison is commonly regarded as the inventor of the light bulb.

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