Roman oil lamp with glass blower (Archaeological Museum of Ptuj, Slovenia)

Mariegola (statute) of the Guild of Venetians Glassmakers (Museum Correr, Venice)

Enyiclopédie de Diderot et d'Alembert. Paris 1751-1772. Planches vol. 10. Dictionnaire Raisonné des Sciences, des Arts et des Métiers.

Bernardino Ramazzini (1633 - 1714) portrait by unknown painter

Glass blower upper lip syphilitic lesion (Archive Clinica del lavoro, Milan) from the book of Aristide Ranelletti 'Le malattie da lavoro', 1924

Painting representing syphilis given credit for by Albrecht Dùrer (1496)

Glass Blower. Photo by unknown artist

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immagine didascalia

Roman oil lamp with glass blower (Archaeological Museum of Ptuj, Slovenia)


immagine didascalia

Mariegola (statute) of the Guild of Venetians Glassmakers (Museum Correr, Venice)


immagine didascalia

Enyiclopédie de Diderot et d'Alembert. Paris 1751-1772. Planches vol. 10. Dictionnaire Raisonné des Sciences, des Arts et des Métiers.


immagine didascalia

Bernardino Ramazzini (1633 - 1714) portrait by unknown painter


immagine didascalia

Glass blower upper lip syphilitic lesion (Archive Clinica del lavoro, Milan) from the book of Aristide Ranelletti 'Le malattie da lavoro', 1924


immagine didascalia

Painting representing syphilis given credit for by Albrecht Dùrer (1496)


immagine didascalia

Glass Blower. Photo by unknown artist


immagine didascalia

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The glass from the nature to man

The glass technique of the nature

Nature produces glass, being the oldest the one contained in meteorites fallen on earth millions of years ago. It also produces glass when lightning strikes sandy soil containing silica, yielding a tubular glass stone called fulgurite (named this way because it is originated by lightning). Obsidian is however the most common volcanic glass originated by the rapid cooling of lava, it is composed of 75% of silica dioxide (Si02) whose melting point occurs only at very high temperatures (about 1710 °C). This nature technique (silica sand and fire) has certainly inspired man who began producing the first glass stones in Mesopotamia during the second millennium BC (late sixteenth or fifteenth century BC.). The discovery of this technique could be a direct consequence of the process of pottery, known since the fifth or fourth millennium BC in northern Syria and which spread into Mesopotamia. Probably some ceramists, observing the hardness of glazing compared to the inner layer of clay, removed the latter obtaining the prototype of an artifact made of glass. The progress of this artisanal technique was linked to the objective of obtaining hard stones resembling nature´s most valuable ones (e.g., lapis lazuli, carnelian, etc.).

The glass technique of Man
Mesopotamia, the land between the Tigris and Euphrates, had sand and firewood (the raw materials) in neighboring Lebanon. The Euphrates River from its source in Turkey to almost the sea linked both regions Syria and Mesopotamia, created that extraordinary navigable commercial route until the Gorges of Carchemish. The importance of an ancient timber trade in the area is confirmed by an order of the king of Babylon, Hammurabi (1700 BC), for the purchase of green wood used to produce coal. Mesopotamia in the city of Mari (2300 - 1800 BC) had a building with precious objects also glassy, but with the decline of the kingdom of Babylon (1500 - 1300 BC), are the areas of the Phoenician coast, the current Syria and Egypt, which take influence in the production of glass.

The technique of glass then passes into the coastal Phoenician cities of Tyre and Sidon, both of which have the sands of the highest quality. The importance of the development of Egyptian glass (XVIII - XIX Dynasty) is confirmed by small vases found in the tomb of Pharaoh Thutmose III (1504-1452 BC), returning from military campaigns in Syria, between 1467 and 1445 BC, he took with him Syrian glassmakers, who gave impulse to the local craftsmanship.

The Blowing with hollow rod to rekindle the fire is Egyptian (3000 - 2000 BC) and this could be the ancient technique that originated the revolutionary glass-blowing (I century BC) that spread with Phoenician masters into the Italian peninsula from Pozzuoli, and then into the northern regions . The rapid execution of blowing allows the diffusion of glass objects in the entire area. Before blowing, the glass was a luxury material as much as linen and paper, as indicated by Cicero in 54 BC Cicero (Pro Rabirio Postum Prayer).

The glass in Venice would have been brought from Aquileia (VII century BC) in ancient times. Aquileia was for long time one of the most important manufacturing centers of Roman glasses, with corporations of glassmakers. Dwellers were forced to flee away because of the invasion of Attila as head of the Huns (452 AD). Other populations move to the Venetian lagoon from other areas. For example, the coastal area occupied by the Greeks of Adria. Adria was a commercial hub that, before and during the Roman period, had business contacts with the Hellenistic Orient and Alexandria of Egypt as evidenced by the pottery, and specially blown glasses, found in its territory.

Venetians added manganese (Mn02), to oxidize iron impurities contained in glass, making it clearer and eliminating the hue green or brown due to the reduced state of iron. On adding lead, borate and a greater amount of soda to glass, Venetians expanded the temperature range within which glass could be worked and were able to obtain more sophisticated forms, thin and refined. They also learned a technique for coloring glass through special additives. In 1295 during the full development of Venetian glass factories, the Doge Pietro Gradenigo (1251-1311) ordered the relocation to the island of Murano, although documents and artifacts show that they were already present. This transfer from Venice was mainly due to the severe fires produced by furnaces which destroyed wooden and straw houses.

The island of Murano becomes the most important European glassmaking center: the "glass island" where artisans with an extraordinary talent have developed, and still today develop new production techniques, new compositions and new colors. Concentrating glass factories in Murano served the Republic, jealous of such an art famous all over the world since its origins , to better control the activities. However, rivalry with Bohemian crystal and the English flint glass (lead crystal glass) led to a major crisis in the fifteenth century. Venice faced the crisis creating chandeliers, best-known artifacts of Murano still today.

The human cost of glass

Furnace fire, besides burning down surrounding houses, produced burns to the glassmakers from the first glass processing based on core and rod. Glass blowing with hollow reed must have also produced an increased risk of infectious epidemics, especially manufacturing larger vases for which most blowers exchanged. The artisans, ignoring the risk of infection as the scientists of the time, passed the rod to one to another, without any precautions. Bacteria and microbes were unknown, but not their effects, scourged Europe with frequent epidemics such as the Black Death in Venice in 1348 which will continue in waves in 1575 and 1630. On the other hand, at the end of the thirteenth century, Health regulations began to rise and one of the first was that established in Venice for its particularly dangerous industries, including glass factories.

Staring at silica glowing sand yielding infrared radiation also caused the opacity of the crystalline lens over time. The temperature raise of the human lens, devoid of blood vessels, impedes the only way to dissipate the excess of accumulated heat. In the eighteenth century, the Encyclopedia of Diderot and D'Alembert it depicts the first protective shields for the glassmakers eyes, very similar to the protective masks of the nowadays welders . The dust of crystalline silica contained in the clay, deposited in the pulmonary alveoli creating silicosis, should not even be an issue at that time, because the work was performed in open spaces and the manufactured amount was limited to artisan groups and commerce, not yet industrial.

Bernardino Ramazzini (1633 - 1714) physician of Carpi, near Modena, active in the Venetian Republic in the period of maximum expansion, first writes a chapter dedicated to glassmakers and mirror manufacturers diseases in the new treaty on diseases of the workers (De morbis Artificum diatriba, first edition 1700 and enlarged in 1713). The work of the glassmakers is so dangerous that can exclusively be performed by strong young men, writes Ramazzini and the violence of fire or toxicity of certain minerals used to color the glass are the cause for the increased risk. The glassmakers in fact suffer acute eye swelling caused by the dryness of the humors and an insatiable thirst that leads them to drink wine and to avoid cold water that generates sudden deaths by congestion.

Sudden changes in temperature from hot to cold of the working environment endangers their lives, even if working naked, and generates lung disease, pleurisy, asthma, and chronic coughs. Suffocation, pulmonary ulcerations and the risk of tuberculosis, as noted in the autopsy of their bodies, are due to the production of colored glass with a mixture of borax and antimony. Even at more risk are manufacturers of mirrors, especially in Venice. They suffer, as the gilders, toxic effects of mercury which is spread on large sheets of glass, that reflect more live images. Ramazzini recalls how in Murano Island, where large mirrors are manufactured, these workers look themselves in the mirrors, made with their own hands, with a scowl and curse the job that they had to do. The described glassmakers diseases are serious and the only chance to remain healthy is the young age of the glassmakers , who at the age of forty wisely quit the job. Giuseppe de Grandi, physician and anatomist of great prestige in Venice, makes Ramazzini aware of the toxicity of the colors.

In 1913, two centuries later, celebrating the bicentenary of Ramazzini´s work, Aristide Ranelletti (1873 - 1945), occupational health physician of Abruzzo, remembers how Venetian Senate called Bernardino Ramazzini as professor of Practical Medicine in the University of Padua, and how he had hesitated to leave Modena, but the flattering thought to be the successor of Domenico Santorini (1681 - 1737), in the most celebrated University of the world at the time, made him decide. Ranelletti himself, in his first Treatise about Work Diseases in 1924, describes the spread of infection among the glass-blowers through the pipe and publishes a photograph of a glass-blower suffering from chancre, syphilitic lesions of the oral mucosa that transmits the infection . The technique of pipe blowing, in fact, determines the presence of infectious epidemics among glassblowers. These include mainly syphilis and tuberculosis, recognized as work diseases.

The geographical origin of syphilis is still debated by historians: French disease by Italians, and Neapolitan disease or "mal napolitaine" by French, Spanish disease by British and American disease by some experts. These differences show how the disease did not enjoy a good reputation since it is linked mainly to promiscuous sexual behavior. The same ironic description of this disease is found in Voltaire's Candide (1694-1778) and in the Memoirs of the Venetian Giacomo Casanova (1725-1798).

However in Italy, is certain, that the disease was brought to Naples in 1494 by the troops of Charles VIII, king of France, and quickly spread also to Venice. Two years later, a pictorial representation of the disease is attributed to Albrecht Dürer (1471 - 1528) probably due to his infection .

Syphilis of glassmakers is also described earlier by Gaetano Pieraccini (1864 - 1957), Tuscany occupational health physician, in his "Treaty work pathology and social therapy" (1906). Prevention, as often happens, delays to be applied, and his colleague Giovanni Petrini in 1913, complains the lack of use in Italy of the individual mouthpiece applied to the blow pipe already used in Sweden and Australia. The cerebral syphilis, linked to the chronicity of the disease, may, with the outbreak of pellagra, have resulted in years of late nineteenth and early twentieth century shelters for "madness" among the glassmakers in the asylum of the island of San Servolo. Although here another chapter could begin. In the following years the syphilis finally disappears from the scene of glassmakers diseases due to the birth of industrialization. However, other non-infectious inflammatory diseases remain among the artisans such as the salivary glands typical of glass-blowers and trumpeters , swelling of the ocular mucosa (pterygium), metals intoxication and respiratory diseases.

The latter still persist in 1980 as reported during the 43rd Italian by the Italian Society of Occupational Health, while environmental pollution by metals in the area of Murano is still mentioned in a recent article published in the Environmental Science and Pollution Research International Journal of January 2010. Murano, its glass artists, its artifacts tell us still today a history of centuries full of suffering, some of which we have described, but also challenges at the international level. Their creativity and experience must be expressed today even in small objects offered to tourists in continuity with the quality of the city´s centuries-old tradition. Venice, Murano, the glass and its artisans must have increasingly healthy working conditions, in a lagoon saved and protected for future generations, in the beauty and quality of its glass, which is still astonishing and enchanting.

Silvana Salerno


400 - 1000  - fino ad oggi   - rev. 0.1.6

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Venice and its lagoons

World Heritage, a dialogue between cultures: which future?

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