Cristallo

{{Short description|Type of glass}} {{For|the mountain|Cristallo (mountain)}} thumb|Cristallo drinking glass circa 1550–1650 thumb|Cristallo stem glass, Louvre '''Cristallo''' is a glass that is totally clear (like rock crystal), without the slight yellow or greenish color originating from iron oxide impurities. This effect is achieved through small additions of manganese oxide.<ref name=douglas>R. W. Douglas: ''A history of glassmaking'', G T Foulis & Co Ltd, Henley-on-Thames, 1972, {{ISBN|0-85429-117-2}}.</ref> Cristallo often has a low lime content, which makes it prone to glass corrosion (otherwise known as glass disease).{{citation needed|date=June 2025}}

The invention of Cristallo glass is attributed to Angelo Barovier around 1450.<ref>Carl I. Gable, ''Murano Magic: Complete Guide to Venetian Glass, its History and Artists'' (Schiffer, 2004), p. 24. {{ISBN|0-7643-1946-9}}.</ref>

==Materials==

In addition to common glass making materials, manganese, quartz pebbles, and alume catino, a particularly suitable form of soda ash, are used in the making of cristallo glass.{{citation needed|date=June 2025}}

Rather than using common sand, crushed quartz pebbles were used instead. The quartz pebbles were typically from the Ticino and the Adige rivers.{{citation needed|date=June 2025}} The quartz pebbles went through a rigorous screening process before being selected for use in cristallo production. The quartz pebbles had to be free of yellow and black veins and also had to be able to produce sparks when struck with steel.{{citation needed|date=June 2025}}

The quartz pebbles which passed the selection process were heated to the point where the stones began to glow, then placed into cold water.{{citation needed|date=June 2025}} Then the pebbles were crushed and ground.

The typical flux used in the production of cristallo was called alume catino. Alume catino was derived from the ash of the salsola soda and salsola kali bushes that grew in the Levantine coastal region. It was found to contain high and constant amounts of sodium and calcium carbonates, necessary to make workable and chemically stable glass.<ref>''Modern Methods for Analysing Archaeological and Historical Glass'', Vol. 1, edited by Koen H. A. Janssens, 2012, p. 524</ref>

The ash of the plants was carefully sieved and placed into water to be gently boiled with constant mixing. Then the ashen mixture was placed into shallow pans to be dried. The alume catino would repeatedly undergo the boiling and drying process until all of the salt was extracted from the ashes.{{citation needed|date=June 2025}}

==Process==

The crushed and ground quartz was mixed with the purified alume catino and constantly mixed at high temperatures. The top of the molten batch would then be skimmed off. By skimming the top of the molten glass, unreacted and undissolved chlorides and sulfates in the mixture were removed.{{citation needed|date=June 2025}}

The molten glass would then be ladled into vats of water. The water removed chloride and sulfate impurities from the mixture. The process of remelting and placing the molten mixture into vats of water was repeated several times until the glass-makers were satisfied.{{citation needed|date=June 2025}}

Next the glass was placed into a furnace that was heated to the highest temperature possible and left there for several days. The material was stirred continually to eliminate defects, such as bubbles.{{citation needed|date=June 2025}}

Then the refined mixture was taken, heated, and shaped into blocks called frit. The frit was then taken and remelted and skimmed once again in order to remove impurities. The batch then had manganese added to the mixture at this time, helping rid the cristallo of any color tints. This step was repeated until the glass-makers were satisfied.{{citation needed|date=June 2025}}

Afterward, the molten mixture was ready to be shaped by glass-makers into pieces of cristalloware.

==References== {{Reflist}} * {{cite journal | last = McCray | first = W. Patrick | authorlink = W. Patrick McCray | title = Glassmaking in Renaissance Italy: The innovation of Venetian cristallo |date=May 1998 | journal = Journal of the Minerals, Metals and Materials Society | volume = 50 | issue = 5 | pages = 14–19 | doi = 10.1007/s11837-998-0024-0 }} * {{cite web | last = Austin | first = Jamie Sue | title = A History of Murano Glass- II | work = Life in Italy | url = http://www.lifeinitaly.com/murano/murano-history-2.asp | access-date = 2010-12-08 | archive-date = 2017-06-13 | archive-url = https://web.archive.org/web/20170613123000/http://www.lifeinitaly.com/murano/murano-history-2.asp | url-status = dead }}

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