Incalmo Glass

Incalmo vessels by Tapio Wirkkala for Venini.

In this post, we will explore one of the classical techniques of glass art. Along with filigrana, latticino, reticello and pezzato, incalmo is a classical Venetian technique well established in the art, even if poorly understood by many outsiders.

‘Incalmo’, in Venetian dialect literally means “graft” as in joining two plants. That is a pretty good description of how this effect is achieved; think of a vase whose bottom-half is one color and top is another. The glass artist blows two separate bubbles of glass, opens them and joins them together to form a single bubble. It is a difficult operation because the two open lips must be exactly the same size to join properly. The process can be continued to add more colors; virtuoso pieces may include several sections, each a different color. In addition, the position of the iron rod that the artist uses to hold the bubble can be changed while the piece is under construction, leading to asymmetrical effects.

16th century incalmo plate,
unknown artist.

The above description is the classical way of achieving incalmo, but modern materials and equipment allow artists to achieve a similar effect with considerably less skill. For instance, precise diameter glass tubing is now available in a wide variety of colors. This can be cut into rings with a saw, then stacked in a kiln and fused together. From there, this “prefabricated incalmo tube can be worked by traditional methods. Whether or not this meets the definition of true incalmo depends entirely on whether one focuses on the method or on the end result.

9-10th century incalmo vase,
Syria or Iraq.

The name ‘incalmo’, was applied to glass in the first half of the twentieth century by the Venini factory on Murano, in Venice. [1] However, both the word and the method are much older. The Venini artisans revived the technique to great acclaim, but Venetian examples date from the sixteenth century and Islamic examples from ninth century Syria have also survived. It is not hard to imagine that this joining technique was experimented with shortly after glassblowing became common around the first century BCE. However, what is truly amazing is that any of these early examples survived to be sold to customers without breaking in the cooling process. The reason for this is a technical issue that we have not discussed yet.

All glass expands a little when it is heated and shrinks when it cools. Different formulations of glass generally expand by differing amounts. When a single piece incorporates more than one type of glass, and the thermal expansions differ significantly, the result is disaster. After the piece is finished it is placed in a kiln where it slowly cools back to room temperature. Because of the mismatch, one area wants to shrink more than the adjacent area and the glass cracks along the join. The expansion and contraction is microscopic, but it is enough to ruin hours and hours of work, leading to much gnashing of teeth the morning after, when the finished work is inspected. 

The Venini glass masters had the benefit of this knowledge, but for earlier artisans, trial and error must have played a big role in determining which formulas were compatible. Different colors mean different metallic additives and to match expansion other ingredients would need to be adjusted. Today, manufacturers produce glass in a series based on expansion; artists can be relatively sure that two different colors from the same series can be “grafted” and not self-destruct when cooled.

[1] I have not absolutely confirmed this, but authoritative secondary references credit Venini, and I can find no mention to "incalmo" as a glass technique prior to the twentieth century.

A Matter of Plagiarism

Francesco Lana Terzi (1631-1687)

Conciatore is pleased to reprise the guest-post of independent researcher Maria Grazzini. Maria studied Antonio Neri under the late Professor Paolo Rossi, philosopher and historian of science at the University of Florence. In 2012, Dr. Grazzini published an annotated English translation of Neri's manuscript in the journal Nuncias. [1] In the course of her research, she discovered a plagiarized version of the manuscript, published by a famous Jesuit professor in Brescia. His version matches Neri's handwritten manuscript of 1614 word for word. Here is what Maria had to say on the subject:

The seventeenth century Jesuit scientist Francesco Lana Terzi (1631-1687) is famous for his design of a "flying boat"; he has been immortalized as the father of aeronautical engineering. What is not generally known is that he plagiarized the entire text of Antonio Neri's manuscript Discorso.

The original was never published by Neri, perhaps due to his premature death, but even as a manuscript, it must have circulated widely. It would be interesting to know the history of its diffusion, in order to understand how it became the subject of plagiarism. Lana Terzi, well known in the Italian Academia of the late seventeenth century, published his  in 1670. [2] The entire chapter 20 of his Prodromo is an exact reproduction of Neri's. Lana Terzi was fascinated by experimentation and manual arts. The Jesuit order refused their members permission to write about magic and alchemy; Jesuits with such esoteric interests could never write books directly devoted to these subjects, however, they could write works on the different aspects of natural philosophy. In this broader context chemical philosophy could be admitted.

Title page of Lana Terzi's Prodromo

Neri was popular in his own time for his glassmaking knowledge. His L'Arte Vetraria  was widely read and its reprints and translations appeared over the centuries. [3] Nevertheless, Neri enjoyed a considerable reputation among his contemporaries also for his 'chemical philosophy'. Discorso is a complete treatise on the subjects of chemistry and philosophy, to all appearance not different from many others written during the sixteenth century. It holds a similar structure, with an introduction defining the subject and the description of procedures. The final part lists possible objections raised against the validity of chemistry and gives Neri's timely responses. In this sense Discorso belongs to the alchemical traditions and Neri shows his deep knowledge of the Paracelsian doctrine and literature. Even so, the main features of the new 'scientific' mindset are present in Neri's treatise: the study of "the great book of nature" and the value of experimental practice. The traditional reliance on the authority of ancient wisdom loses its legitimacy. "We should not so easily give credence to all the histories," Neri claims, but we should "prove the possibility of this art of transmutation with certain […] experiences". Knowledge is acquired "with the practice of many experiences." It does not come from a divine revelation or from the study of many books.
There is no contradiction between the alchemist Neri and the glass-conciatore Neri; the will of gaining a deep knowledge of nature, based on the observation and experimentation, is common to both. Neri is always 'the technician' and never 'the philosopher'. Alchemy, the "Great Art," is the result of a deep study of nature and its aim is not to give an imitation of nature, but to make it perfect.

The 'modernity' of Neri can also be understood in his way of talking about chemical philosophy. He does not pretend to teach eternal truths, but only to indicate the way to achieve greater knowledge, by "understanding the modus operandi of nature." Consequently, the writer does not use the form of a dogmatic essay, but that of a conversational chat, or 'discourse'.

It would be interesting to discover how Lana Terzi came into possession of Neri's manuscript. Perhaps he was attracted by the mixture of old and new which was also a predominant theme of his time, when different models of knowledge coexisted and intertwined. Discorso offered him the chance of introducing the topic of alchemy without being accused of magism.

-M. G. Grazzini

[1] Grazzini 2012.
[2] Lana Terzi 1670.
[3] Neri 1612, 1613.
* this post first appeared here on 20 November 2013.

Botanical Gardens

Rudolf  II as "Vertumnus"(c. 1590)

Giuseppe Arcimboldo.

In 1543-44 new botanical gardens were founded in Pisa; L’Orto Botanico was its Italian name. It was the very first garden devoted to the research of plants. Literally within a year, similar gardens sprung up in Padua and Florence, and many other cities followed shortly thereafter. Exotic foreign species as well as important local plants were grown, studied, harvested distilled, and imbibed. These horticultural stations became centerpieces of medical programs throughout Italy, and then greater Europe. The concept of herbal (“simples”) gardens was centuries old. Almost every monastery, convent and hospital maintained a space to grow the plants they needed to transform into medicines for care of the infirmed. The grafting of fruit trees was actively practiced since before Roman times, but these new gardens were specifically planted as research spaces and run by universities. 

When Neri Neri, the father of glassmaker Antonio Neri, studied medicine at the Studio Fiorentino  in the mid 1550s, there can be no doubt he spent time at the gardens in Florence, and quite possibly at the ones in Pisa. (The Pisa gardens were moved twice before arriving at their current location in 1591). This was a period of vigorous expansion in the field of herbal medicine. Competition was fierce to obtain and study medicinal plants from around the globe. Cosimo I de’ Medici poured money into the medical school in Pisa, attracting students and faculty from around Europe. In 1554 famed botanist and physician Andrea Cesalpino took over the Pisa gardens  from his teacher, Luca Ghini, who first built them. 

In 1602, Neri was to be found working alongside Niccolò Sisti at the grand duke’s secondary glass furnace along the Arno River in Pisa. According to Neri’s own account, Pisa is where he worked on ferns as an alternative plant salt for glass and mentions many other plants with which he experimented: 

Set about making ash in the way previously described, however use the husks and stalks of broad beans after the farmhands have thrashed and shelled them. The same may be made from the ashes of cabbages, or a thorn bush that bears small fruit, called the blackberry, even from millet, rush, marsh reeds, and from many other plants that will relinquish their salt.

In a letter to Neri from his friend Emanuel Ximenes, the Antwerp based Portuguese banker expressed surprise that Neri was able to devise a fern based glass salt recipe so quickly. In all likelihood, Neri would have had access to the botanical gardens and the small adjacent laboratory located just a few blocks from the glass furnace. In the period of time the glassmaker spent there, the directorate of the gardens changed hands from Francesco Malocchi to Marco Cornacchini. Both of these men avidly pursued new botanical based cures, and corresponded internationally. 

In his Glassmaking book, L’Arte Vetraria, Neri devotes a number of recipes to making paint pigments from flower blossoms. While he could have easily obtained his stock material from any number of sources, the botanical gardens would have certainly provided a convenient cache of many different varieties.

In the winter of 1603-4 Neri traveled From Pisa to visit his friend in Antwerp. If he followed Ximenes suggested route, he would have passed back through his native Florence, then on to Venice where he would meet up with a caravan of merchants on their way to the Frankfurt spring fair, and then on to Antwerp by river. Upon his return to Italy, seven years later, he wrote his glassmaking book, but then devoted himself fully to alchemy and medicine. In January of 1614, in what might be the very last manuscript he worked on before his death, he wrote about some recipes “copied from an old book here in Pisa.” At that time, the director of the botanical gardens was Domenico Vigna, who continued to direct the gardens on and off until 1634.

It would be interesting to know how Neri the alchemist thought about his raw materials. Did he see all the possibilities of what could be made with them? For instance, how did he approach a towering pile of May ferns, large enough to produce a hundred pounds of ash, or a giant sack of rose petals? Did he ever lean forward and breathe in the delicious musty aroma? Did he ever dig in with his hands and bury his face in an arm-load of soft, pure color? How could he not?

*This post first appeared here 22 Jan 2014.

A Matter of Plagiarism

Francesco Lana Terzi (1631-1687)

Conciatore is pleased to reprise the guest-post of independent researcher Maria Grazzini. Maria studied Antonio Neri under the late Professor Paolo Rossi, philosopher and historian of science at the University of Florence. In 2012, Dr. Grazzini published an annotated English translation of Neri's manuscript in the journal Nuncias. [1] In the course of her research, she discovered a plagiarized version of the manuscript, published by 
a famous Jesuit professor in Brescia. His version matches Neri's handwritten manuscript of 1614 word for word. Here is what Maria had to say on the subject:

The seventeenth century Jesuit scientist Francesco Lana Terzi (1631-1687) is famous for his design of a "flying boat"; he has been immortalized as the father of aeronautical engineering. What is not generally known is that he plagiarized the entire text of Antonio Neri's manuscript Discorso.

The original was never published by Neri, perhaps due to his premature death, but even as a manuscript, it must have circulated widely. It would be interesting to know the history of its diffusion, in order to understand how it became the subject of plagiarism. Lana Terzi, well known in the Italian Academia of the late seventeenth century, published his  in 1670. [2] The entire chapter 20 of his Prodromo is an exact reproduction of Neri's. Lana Terzi was fascinated by experimentation and manual arts. The Jesuit order refused their members permission to write about magic and alchemy; Jesuits with such esoteric interests could never write books directly devoted to these subjects, however, they could write works on the different aspects of natural philosophy. In this broader context chemical philosophy could be admitted.

Title page of Lana Terzi's Prodromo

Neri was popular in his own time for his glassmaking knowledge. His L'Arte Vetraria  was widely read and its reprints and translations appeared over the centuries. [3] Nevertheless, Neri enjoyed a considerable reputation among his contemporaries also for his 'chemical philosophy'. Discorso is a complete treatise on the subjects of chemistry and philosophy, to all appearance not different from many others written during the sixteenth century. It holds a similar structure, with an introduction defining the subject and the description of procedures. The final part lists possible objections raised against the validity of chemistry and gives Neri's timely responses. In this sense Discorso belongs to the alchemical traditions and Neri shows his deep knowledge of the Paracelsian doctrine and literature. Even so, the main features of the new 'scientific' mindset are present in Neri's treatise: the study of "the great book of nature" and the value of experimental practice. The traditional reliance on the authority of ancient wisdom loses its legitimacy. "We should not so easily give credence to all the histories," Neri claims, but we should "prove the possibility of this art of transmutation with certain […] experiences". Knowledge is acquired "with the practice of many experiences." It does not come from a divine revelation or from the study of many books.
There is no contradiction between the alchemist Neri and the glass-conciatore Neri; the will of gaining a deep knowledge of nature, based on the observation and experimentation, is common to both. Neri is always 'the technician' and never 'the philosopher'. Alchemy, the "Great Art," is the result of a deep study of nature and its aim is not to give an imitation of nature, but to make it perfect.

The 'modernity' of Neri can also be understood in his way of talking about chemical philosophy. He does not pretend to teach eternal truths, but only to indicate the way to achieve greater knowledge, by "understanding the modus operandi of nature." Consequently, the writer does not use the form of a dogmatic essay, but that of a conversational chat, or 'discourse'.

It would be interesting to discover how Lana Terzi came into possession of Neri's manuscript. Perhaps he was attracted by the mixture of old and new which was also a predominant theme of his time, when different models of knowledge coexisted and intertwined. Discorso offered him the chance of introducing the topic of alchemy without being accused of magism.

-M. G. Grazzini

[1] Grazzini 2012.
[2] Lana Terzi 1670.
[3] Neri 1612, 1613.
* this post first appeared here on 20 November 2013.

Incalmo of Venice

Incalmo vessels by Tapio Wirkkala for Venini.

In this post, we will explore one of the classical techniques of glass art. Along with filigrana, latticino, reticello and pezzato, incalmo is a classical Venetian technique well established in the art, even if poorly understood by many outsiders.

‘Incalmo’, in Venetian dialect literally means “graft” as in joining two plants. That is a pretty good description of how this effect is achieved; think of a vase whose bottom-half is one color and top is another. The glass artist blows two separate bubbles of glass, opens them and joins them together to form a single bubble. It is a difficult operation because the two open lips must be exactly the same size to join properly. The process can be continued to add more colors; virtuoso pieces may include several sections, each a different color. In addition, the position of the iron rod that the artist uses to hold the bubble can be changed while the piece is under construction, leading to asymmetrical effects.

16th century incalmo plate,
unknown artist.

The above description is the classical way of achieving incalmo, but modern materials and equipment allow artists to achieve a similar effect with considerably less skill. For instance, precise diameter glass tubing is now available in a wide variety of colors. This can be cut into rings with a saw, then stacked in a kiln and fused together. From there, this “prefabricated incalmo tube can be worked by traditional methods. Whether or not this meets the definition of true incalmo depends entirely on whether one focuses on the method or on the end result.

9-10th century incalmo vase,
Syria or Iraq.

The name ‘incalmo’, was applied to glass in the first half of the twentieth century by the Venini factory on Murano, in Venice. [1] However, both the word and the method are much older. The Venini artisans revived the technique to great acclaim, but Venetian examples date from the sixteenth century and Islamic examples from ninth century Syria have also survived. It is not hard to imagine that this joining technique was experimented with shortly after glassblowing became common around the first century BCE. However, what is truly amazing is that any of these early examples survived to be sold to customers without breaking in the cooling process. The reason for this is a technical issue that we have not discussed yet.

All glass expands a little when it is heated and shrinks when it cools. Different formulations of glass generally expand by differing amounts. When a single piece incorporates more than one type of glass, and the thermal expansions differ significantly, the result is disaster. After the piece is finished it is placed in a kiln where it slowly cools back to room temperature. Because of the mismatch, one area wants to shrink more than the adjacent area and the glass cracks along the join. The expansion and contraction is microscopic, but it is enough to ruin hours and hours of work, leading to much gnashing of teeth the morning after, when the finished work is inspected. 

The Venini glass masters had the benefit of this knowledge, but for earlier artisans, trial and error must have played a big role in determining which formulas were compatible. Different colors mean different metallic additives and to match expansion other ingredients would need to be adjusted. Today, manufacturers produce glass in a series based on expansion; artists can be relatively sure that two different colors from the same series can be “grafted” and not self-destruct when cooled.

[1] I have not absolutely confirmed this, but authoritative secondary references credit Venini, and I can find no mention to "incalmo" as a glass technique prior to the twentieth century.

Botanical Gardens

Rudolf  II as "Vertumnus"(c. 1590)

Giuseppe Arcimboldo.

In 1543-44 new botanical gardens were founded in Pisa; L’Orto Botanico was its Italian name. It was the very first garden devoted to the research of plants. Literally within a year, similar gardens sprung up in Padua and Florence, and many other cities followed shortly thereafter. Exotic foreign species as well as important local plants were grown, studied, harvested distilled, and imbibed. These horticultural stations became centerpieces of medical programs throughout Italy, and then greater Europe. The concept of herbal (“simples”) gardens was centuries old. Almost every monastery, convent and hospital maintained a space to grow the plants they needed to transform into medicines for care of the infirmed. The grafting of fruit trees was actively practiced since before Roman times, but these new gardens were specifically planted as research spaces and run by universities. 

When Neri Neri, the father of glassmaker Antonio Neri, studied medicine at the Studio Fiorentino  in the mid 1550s, there can be no doubt he spent time at the gardens in Florence, and quite possibly at the ones in Pisa. (The Pisa gardens were moved twice before arriving at their current location in 1591). This was a period of vigorous expansion in the field of herbal medicine. Competition was fierce to obtain and study medicinal plants from around the globe. Cosimo I de’ Medici poured money into the medical school in Pisa, attracting students and faculty from around Europe. In 1554 famed botanist and physician Andrea Cesalpino took over the Pisa gardens  from his teacher, Luca Ghini, who first built them. 

In 1602, Neri was to be found working alongside Niccolò Sisti at the grand duke’s secondary glass furnace along the Arno River in Pisa. According to Neri’s own account, Pisa is where he worked on ferns as an alternative plant salt for glass and mentions many other plants with which he experimented: 

Set about making ash in the way previously described, however use the husks and stalks of broad beans after the farmhands have thrashed and shelled them. The same may be made from the ashes of cabbages, or a thorn bush that bears small fruit, called the blackberry, even from millet, rush, marsh reeds, and from many other plants that will relinquish their salt.

In a letter to Neri from his friend Emanuel Ximenes, the Antwerp based Portuguese banker expressed surprise that Neri was able to devise a fern based glass salt recipe so quickly. In all likelihood, Neri would have had access to the botanical gardens and the small adjacent laboratory located just a few blocks from the glass furnace. In the period of time the glassmaker spent there, the directorate of the gardens changed hands from Francesco Malocchi to Marco Cornacchini. Both of these men avidly pursued new botanical based cures, and corresponded internationally. 

In his Glassmaking book, L’Arte Vetraria, Neri devotes a number of recipes to making paint pigments from flower blossoms. While he could have easily obtained his stock material from any number of sources, the botanical gardens would have certainly provided a convenient cache of many different varieties.

In the winter of 1603-4 Neri traveled From Pisa to visit his friend in Antwerp. If he followed Ximenes suggested route, he would have passed back through his native Florence, then on to Venice where he would meet up with a caravan of merchants on their way to the Frankfurt spring fair, and then on to Antwerp by river. Upon his return to Italy, seven years later, he wrote his glassmaking book, but then devoted himself fully to alchemy and medicine. In January of 1614, in what might be the very last manuscript he worked on before his death, he wrote about some recipes “copied from an old book here in Pisa.” At that time, the director of the botanical gardens was Domenico Vigna, who continued to direct the gardens on and off until 1634.

It would be interesting to know how Neri the alchemist thought about his raw materials. Did he see all the possibilities of what could be made with them? For instance, how did he approach a towering pile of May ferns, large enough to produce a hundred pounds of ash, or a giant sack of rose petals? Did he ever lean forward and breathe in the delicious musty aroma? Did he ever dig in with his hands and bury his face in an arm-load of soft, pure color? How could he not?

*This post first appeared here 22 Jan 2014.

A Matter of Plagiarism

Francesco Lana Terzi (1631-1687)

Conciatore is pleased to reprise the guest-post of independent researcher Maria Grazzini. Maria studied Antonio Neri under the late Professor Paolo Rossi, philosopher and historian of science at the University of Florence. In 2012, Dr. Grazzini published an annotated English translation of Neri's manuscript in the journal Nuncias. [1] In the course of her research, she discovered a plagiarized version of the manuscript, published by 
a famous Jesuit professor in Brescia. His version matches Neri's handwritten manuscript of 1614 word for word. Here is what Maria had to say on the subject:

The seventeenth century Jesuit scientist Francesco Lana Terzi (1631-1687) is famous for his design of a "flying boat"; he has been immortalized as the father of aeronautical engineering. What is not generally known is that he plagiarized the entire text of Antonio Neri's manuscript Discorso.

The original was never published by Neri, perhaps due to his premature death, but even as a manuscript, it must have circulated widely. It would be interesting to know the history of its diffusion, in order to understand how it became the subject of plagiarism. Lana Terzi, well known in the Italian Academia of the late seventeenth century, published his  in 1670. [2] The entire chapter 20 of his Prodromo is an exact reproduction of Neri's. Lana Terzi was fascinated by experimentation and manual arts. The Jesuit order refused their members permission to write about magic and alchemy; Jesuits with such esoteric interests could never write books directly devoted to these subjects, however, they could write works on the different aspects of natural philosophy. In this broader context chemical philosophy could be admitted.

Title page of Lana Terzi's Prodromo

Neri was popular in his own time for his glassmaking knowledge. His L'Arte Vetraria  was widely read and its reprints and translations appeared over the centuries. [3] Nevertheless, Neri enjoyed a considerable reputation among his contemporaries also for his 'chemical philosophy'. Discorso is a complete treatise on the subjects of chemistry and philosophy, to all appearance not different from many others written during the sixteenth century. It holds a similar structure, with an introduction defining the subject and the description of procedures. The final part lists possible objections raised against the validity of chemistry and gives Neri's timely responses. In this sense Discorso belongs to the alchemical traditions and Neri shows his deep knowledge of the Paracelsian doctrine and literature. Even so, the main features of the new 'scientific' mindset are present in Neri's treatise: the study of "the great book of nature" and the value of experimental practice. The traditional reliance on the authority of ancient wisdom loses its legitimacy. "We should not so easily give credence to all the histories," Neri claims, but we should "prove the possibility of this art of transmutation with certain […] experiences". Knowledge is acquired "with the practice of many experiences." It does not come from a divine revelation or from the study of many books.
There is no contradiction between the alchemist Neri and the glass-conciatore Neri; the will of gaining a deep knowledge of nature, based on the observation and experimentation, is common to both. Neri is always 'the technician' and never 'the philosopher'. Alchemy, the "Great Art," is the result of a deep study of nature and its aim is not to give an imitation of nature, but to make it perfect.

The 'modernity' of Neri can also be understood in his way of talking about chemical philosophy. He does not pretend to teach eternal truths, but only to indicate the way to achieve greater knowledge, by "understanding the modus operandi of nature." Consequently, the writer does not use the form of a dogmatic essay, but that of a conversational chat, or 'discourse'.

It would be interesting to discover how Lana Terzi came into possession of Neri's manuscript. Perhaps he was attracted by the mixture of old and new which was also a predominant theme of his time, when different models of knowledge coexisted and intertwined. Discorso offered him the chance of introducing the topic of alchemy without being accused of magism.

-M. G. Grazzini

[1] Grazzini 2012.
[2] Lana Terzi 1670.
[3] Neri 1612, 1613.
* this post first appeared here on 20 November 2013.

Incalmo of Venice

Incalmo vessels by Tapio Wirkkala for Venini.

In this post, we will explore one of the classical techniques of glass art. Along with filigrana, latticino, reticello and pezzato, incalmo is a classical Venetian technique well established in the art, even if poorly understood by many outsiders.

‘Incalmo’, in Venetian dialect literally means “graft” as in joining two plants. That is a pretty good description of how this effect is achieved; think of a vase whose bottom-half is one color and top is another. The glass artist blows two separate bubbles of glass, opens them and joins them together to form a single bubble. It is a difficult operation because the two open lips must be exactly the same size to join properly. The process can be continued to add more colors; virtuoso pieces may include several sections, each a different color. In addition, the position of the iron rod that the artist uses to hold the bubble can be changed while the piece is under construction, leading to asymmetrical effects.

16th century incalmo plate,
unknown artist.

The above description is the classical way of achieving incalmo, but modern materials and equipment allow artists to achieve a similar effect with considerably less skill. For instance, precise diameter glass tubing is now available in a wide variety of colors. This can be cut into rings with a saw, then stacked in a kiln and fused together. From there, this “prefabricated incalmo tube can be worked by traditional methods. Whether or not this meets the definition of true incalmo depends entirely on whether one focuses on the method or on the end result.

9-10th century incalmo vase,
Syria or Iraq.

The name ‘incalmo’, was applied to glass in the first half of the twentieth century by the Venini factory on Murano, in Venice. [1] However, both the word and the method are much older. The Venini artisans revived the technique to great acclaim, but Venetian examples date from the sixteenth century and Islamic examples from ninth century Syria have also survived. It is not hard to imagine that this joining technique was experimented with shortly after glassblowing became common around the first century BCE. However, what is truly amazing is that any of these early examples survived to be sold to customers without breaking in the cooling process. The reason for this is a technical issue that we have not discussed yet.

All glass expands a little when it is heated and shrinks when it cools. Different formulations of glass generally expand by differing amounts. When a single piece incorporates more than one type of glass, and the thermal expansions differ significantly, the result is disaster. After the piece is finished it is placed in a kiln where it slowly cools back to room temperature. Because of the mismatch, one area wants to shrink more than the adjacent area and the glass cracks along the join. The expansion and contraction is microscopic, but it is enough to ruin hours and hours of work, leading to much gnashing of teeth the morning after, when the finished work is inspected. 

The Venini glass masters had the benefit of this knowledge, but for earlier artisans, trial and error must have played a big role in determining which formulas were compatible. Different colors mean different metallic additives and to match expansion other ingredients would need to be adjusted. Today, manufacturers produce glass in a series based on expansion; artists can be relatively sure that two different colors from the same series can be “grafted” and not self-destruct when cooled.

[1] I have not absolutely confirmed this, but authoritative secondary references credit Venini, and I can find no mention to "incalmo" as a glass technique prior to the twentieth century.

Botanical Gardens

Rudolf  II as "Vertumnus"(c. 1590)

Giuseppe Arcimboldo.

In 1543-44 new botanical gardens were founded in Pisa; L’Orto Botanico was its Italian name. It was the very first garden devoted to the research of plants. Literally within a year, similar gardens sprung up in Padua and Florence, and many other cities followed shortly thereafter. Exotic foreign species as well as important local plants were grown, studied, harvested distilled, and imbibed. These horticultural stations became centerpieces of medical programs throughout Italy, and then greater Europe. The concept of herbal (“simples”) gardens was centuries old. Almost every monastery, convent and hospital maintained a space to grow the plants they needed to transform into medicines for care of the infirmed. The grafting of fruit trees was actively practiced since before Roman times, but these new gardens were specifically planted as research spaces and run by universities. 

When Neri Neri, the father of glassmaker Antonio Neri, studied medicine at the Studio Fiorentino  in the mid 1550s, there can be no doubt he spent time at the gardens in Florence, and quite possibly at the ones in Pisa. (The Pisa gardens were moved twice before arriving at their current location in 1591). This was a period of vigorous expansion in the field of herbal medicine. Competition was fierce to obtain and study medicinal plants from around the globe. Cosimo I de’ Medici poured money into the medical school in Pisa, attracting students and faculty from around Europe. In 1554 famed botanist and physician Andrea Cesalpino took over the Pisa gardens  from his teacher, Luca Ghini, who first built them. 

In 1602, Neri was to be found working alongside Niccolò Sisti at the grand duke’s secondary glass furnace along the Arno River in Pisa. According to Neri’s own account, Pisa is where he worked on ferns as an alternative plant salt for glass and mentions many other plants with which he experimented: 

Set about making ash in the way previously described, however use the husks and stalks of broad beans after the farmhands have thrashed and shelled them. The same may be made from the ashes of cabbages, or a thorn bush that bears small fruit, called the blackberry, even from millet, rush, marsh reeds, and from many other plants that will relinquish their salt.

In a letter to Neri from his friend Emanuel Ximenes, the Antwerp based Portuguese banker expressed surprise that Neri was able to devise a fern based glass salt recipe so quickly. In all likelihood, Neri would have had access to the botanical gardens and the small adjacent laboratory located just a few blocks from the glass furnace. In the period of time the glassmaker spent there, the directorate of the gardens changed hands from Francesco Malocchi to Marco Cornacchini. Both of these men avidly pursued new botanical based cures, and corresponded internationally. 

In his Glassmaking book, L’Arte Vetraria, Neri devotes a number of recipes to making paint pigments from flower blossoms. While he could have easily obtained his stock material from any number of sources, the botanical gardens would have certainly provided a convenient cache of many different varieties.

In the winter of 1603-4 Neri traveled From Pisa to visit his friend in Antwerp. If he followed Ximenes suggested route, he would have passed back through his native Florence, then on to Venice where he would meet up with a caravan of merchants on their way to the Frankfurt spring fair, and then on to Antwerp by river. Upon his return to Italy, seven years later, he wrote his glassmaking book, but then devoted himself fully to alchemy and medicine. In January of 1614, in what might be the very last manuscript he worked on before his death, he wrote about some recipes “copied from an old book here in Pisa.” At that time, the director of the botanical gardens was Domenico Vigna, who continued to direct the gardens on and off until 1634.

It would be interesting to know how Neri the alchemist thought about his raw materials. Did he see all the possibilities of what could be made with them? For instance, how did he approach a towering pile of May ferns, large enough to produce a hundred pounds of ash, or a giant sack of rose petals? Did he ever lean forward and breathe in the delicious musty aroma? Did he ever dig in with his hands and bury his face in an arm-load of soft, pure color? How could he not?

*This post first appeared here 22 Jan 2014.

A matter of Plagiarism

Francesco Lana Terzi (1631-1687)

Conciatore is pleased to reprise the guest-post of independent researcher Maria Grazzini. Maria studied Antonio Neri under the late Professor Paolo Rossi, philosopher and historian of science at the University of Florence. In 2012, Dr. Grazzini published an annotated English translation of Neri's manuscript in the journal Nuncias. [1] In the course of her research, she discovered a plagiarized version of the manuscript, published by 
a famous Jesuit professor in Brescia. His version matches Neri's handwritten manuscript of 1614 word for word. Here is what Maria had to say on the subject:

The seventeenth century Jesuit scientist Francesco Lana Terzi (1631-1687) is famous for his design of a "flying boat"; he has been immortalized as the father of aeronautical engineering. What is not generally known is that he plagiarized the entire text of Antonio Neri's manuscript Discorso.

The original was never published by Neri, perhaps due to his premature death, but even as a manuscript, it must have circulated widely. It would be interesting to know the history of its diffusion, in order to understand how it became the subject of plagiarism. Lana Terzi, well known in the Italian Academia of the late seventeenth century, published his  in 1670. [2] The entire chapter 20 of his Prodromo is an exact reproduction of Neri's. Lana Terzi was fascinated by experimentation and manual arts. The Jesuit order refused their members permission to write about magic and alchemy; Jesuits with such esoteric interests could never write books directly devoted to these subjects, however, they could write works on the different aspects of natural philosophy. In this broader context chemical philosophy could be admitted.

Title page of Lana Terzi's Prodromo

Neri was popular in his own time for his glassmaking knowledge. His L'Arte Vetraria  was widely read and its reprints and translations appeared over the centuries. [3] Nevertheless, Neri enjoyed a considerable reputation among his contemporaries also for his 'chemical philosophy'. Discorso is a complete treatise on the subjects of chemistry and philosophy, to all appearance not different from many others written during the sixteenth century. It holds a similar structure, with an introduction defining the subject and the description of procedures. The final part lists possible objections raised against the validity of chemistry and gives Neri's timely responses. In this sense Discorso belongs to the alchemical traditions and Neri shows his deep knowledge of the Paracelsian doctrine and literature. Even so, the main features of the new 'scientific' mindset are present in Neri's treatise: the study of "the great book of nature" and the value of experimental practice. The traditional reliance on the authority of ancient wisdom loses its legitimacy. "We should not so easily give credence to all the histories," Neri claims, but we should "prove the possibility of this art of transmutation with certain […] experiences". Knowledge is acquired "with the practice of many experiences." It does not come from a divine revelation or from the study of many books.
There is no contradiction between the alchemist Neri and the glass-conciatore Neri; the will of gaining a deep knowledge of nature, based on the observation and experimentation, is common to both. Neri is always 'the technician' and never 'the philosopher'. Alchemy, the "Great Art," is the result of a deep study of nature and its aim is not to give an imitation of nature, but to make it perfect.

The 'modernity' of Neri can also be understood in his way of talking about chemical philosophy. He does not pretend to teach eternal truths, but only to indicate the way to achieve greater knowledge, by "understanding the modus operandi of nature." Consequently, the writer does not use the form of a dogmatic essay, but that of a conversational chat, or 'discourse'.

It would be interesting to discover how Lana Terzi came into possession of Neri's manuscript. Perhaps he was attracted by the mixture of old and new which was also a predominant theme of his time, when different models of knowledge coexisted and intertwined. Discorso offered him the chance of introducing the topic of alchemy without being accused of magism.

-M. G. Grazzini

[1] Grazzini 2012.
[2] Lana Terzi 1670.
[3] Neri 1612, 1613.
* this post first appeared here on 20 November 2013.

Botanical Gardens

Rudolf  II as "Vertumnus"(c. 1590)

Giuseppe Arcimboldo.

In 1543-44 new botanical gardens were founded in Pisa; L’Orto Botanico was its Italian name. It was the very first garden devoted to the research of plants. Literally within a year, similar gardens sprung up in Padua and Florence, and many other cities followed shortly thereafter. Exotic foreign species as well as important local plants were grown, studied, harvested distilled, and imbibed. These horticultural stations became centerpieces of medical programs throughout Italy, and then greater Europe. The concept of herbal (“simples”) gardens was centuries old. Almost every monastery, convent and hospital maintained a space to grow the plants they needed to transform into medicines for care of the infirmed. The grafting of fruit trees was actively practiced since before Roman times, but these new gardens were specifically planted as research spaces and run by universities. 

When Neri Neri, the father of glassmaker Antonio Neri, studied medicine at the Studio Fiorentino  in the mid 1550s, there can be no doubt he spent time at the gardens in Florence, and quite possibly at the ones in Pisa. (The Pisa gardens were moved twice before arriving at their current location in 1591). This was a period of vigorous expansion in the field of herbal medicine. Competition was fierce to obtain and study medicinal plants from around the globe. Cosimo I de’ Medici poured money into the medical school in Pisa, attracting students and faculty from around Europe. In 1554 famed botanist and physician Andrea Cesalpino took over the Pisa gardens  from his teacher, Luca Ghini, who first built them. 

In 1602, Neri was to be found working alongside Niccolò Sisti at the grand duke’s secondary glass furnace along the Arno River in Pisa. According to Neri’s own account, Pisa is where he worked on ferns as an alternative plant salt for glass and mentions many other plants with which he experimented: 

Set about making ash in the way previously described, however use the husks and stalks of broad beans after the farmhands have thrashed and shelled them. The same may be made from the ashes of cabbages, or a thorn bush that bears small fruit, called the blackberry, even from millet, rush, marsh reeds, and from many other plants that will relinquish their salt.

In a letter to Neri from his friend Emanuel Ximenes, the Antwerp based Portuguese banker expressed surprise that Neri was able to devise a fern based glass salt recipe so quickly. In all likelihood, Neri would have had access to the botanical gardens and the small adjacent laboratory located just a few blocks from the glass furnace. In the period of time the glassmaker spent there, the directorate of the gardens changed hands from Francesco Malocchi to Marco Cornacchini. Both of these men avidly pursued new botanical based cures, and corresponded internationally. 

In his Glassmaking book, L’Arte Vetraria, Neri devotes a number of recipes to making paint pigments from flower blossoms. While he could have easily obtained his stock material from any number of sources, the botanical gardens would have certainly provided a convenient cache of many different varieties.

In the winter of 1603-4 Neri traveled From Pisa to visit his friend in Antwerp. If he followed Ximenes suggested route, he would have passed back through his native Florence, then on to Venice where he would meet up with a caravan of merchants on their way to the Frankfort spring fair, and then on to Antwerp by river. Upon his return to Italy, seven years later, he wrote his glassmaking book, but then devoted himself fully to alchemy and medicine. In January of 1614, in what might be the very last manuscript he worked on before his death, he wrote about some recipes “copied from an old book here in Pisa.” At that time, the director of the botanical gardens was Domenico Vigna, who continued to direct the gardens on and off until 1634.

It would be interesting to know how Neri the alchemist thought about his raw materials. Did he see all the possibilities of what could be made with them? For instance, how did he approach a towering pile of May ferns, large enough to produce a hundred pounds of ash, or a giant sack of rose petals? Did he ever lean forward and breathe in the delicious musty aroma? Did he ever dig in with his hands and bury his face in an arm-load of soft, pure color? How could he not?

*This post first appeared here 22 Jan 2014.

Incalmo

Incalmo vessels by Tapio Wirkkala for Venini.

In this post, we will explore one of the classical techniques of glass art. Along with filigrana, latticino, reticello and pezzato, incalmo is a classical Venetian technique well established in the art, even if poorly understood by many outsiders.

‘Incalmo’, in Venetian dialect literally means “graft” as in joining two plants. That is a pretty good description of how this effect is achieved; think of a vase whose bottom-half is one color and top is another. The glass artist blows two separate bubbles of glass, opens them and joins them together to form a single bubble. It is a difficult operation because the two open lips must be exactly the same size to join properly. The process can be continued to add more colors; virtuoso pieces may include several sections, each a different color. In addition, the position of the iron rod that the artist uses to hold the bubble can be changed while the piece is under construction, leading to asymmetrical effects.

16th century incalmo plate,
unknown artist.

The above description is the classical way of achieving incalmo, but modern materials and equipment allow artists to achieve a similar effect with considerably less skill. For instance, precise diameter glass tubing is now available in a wide variety of colors. This can be cut into rings with a saw, then stacked in a kiln and fused together. From there, this “prefabricated incalmo tube can be worked by traditional methods. Whether or not this meets the definition of true incalmo depends entirely on whether one focuses on the method or on the end result.

9-10th century incalmo vase,
Syria or Iraq.

The name ‘incalmo’, was applied to glass in the first half of the twentieth century by the Venini factory on Murano, in Venice. [1] However, both the word and the method are much older. The Venini artisans revived the technique to great acclaim, but Venetian examples date from the sixteenth century and Islamic examples from ninth century Syria have also survived. It is not hard to imagine that this joining technique was experimented with shortly after glassblowing became common around the first century BCE. However, what is truly amazing is that any of these early examples survived to be sold to customers without breaking in the cooling process. The reason for this is a technical issue that we have not discussed yet.

All glass expands a little when it is heated and shrinks when it cools. Different formulations of glass generally expand by differing amounts. When a single piece incorporates more than one type of glass, and the thermal expansions differ significantly, the result is disaster. After the piece is finished it is placed in a kiln where it slowly cools back to room temperature. Because of the mismatch, one area wants to shrink more than the adjacent area and the glass cracks along the join. The expansion and contraction is microscopic, but it is enough to ruin hours and hours of work, leading to much gnashing of teeth the morning after, when the finished work is inspected. 

The Venini glass masters had the benefit of this knowledge, but for earlier artisans, trial and error must have played a big role in determining which formulas were compatible. Different colors mean different metallic additives and to match expansion other ingredients would need to be adjusted. Today, manufacturers produce glass in a series based on expansion; artists can be relatively sure that two different colors from the same series can be “grafted” and not self-destruct when cooled.

[1] I have not absolutely confirmed this, but authoritative secondary references credit Venini, and I can find no mention to "incalmo" as a glass technique prior to the twentieth century.

A Matter of Plagiarism

Francesco Lana Terzi (1631-1687)

Conciatore is pleased to reprise the guest-post of independent researcher Maria Grazzini. Maria studied Antonio Neri under the late Professor Paolo Rossi, philosopher and historian of science at the University of Florence. In 2012, Dr. Grazzini published an annotated English translation of Neri's manuscript in the journal Nuncias. [1] In the course of her research, she discovered a plagiarized version of the manuscript, published by 
a famous Jesuit professor in Brescia. His version matches Neri's handwritten manuscript of 1614 word for word. Here is what Maria had to say on the subject:

The seventeenth century Jesuit scientist Francesco Lana Terzi (1631-1687) is famous for his design of a "flying boat"; he has been immortalized as the father of aeronautical engineering. What is not generally known is that he plagiarized the entire text of Antonio Neri's manuscript Discorso.

The original was never published by Neri, perhaps due to his premature death, but even as a manuscript, it must have circulated widely. It would be interesting to know the history of its diffusion, in order to understand how it became the subject of plagiarism. Lana Terzi, well known in the Italian Academia of the late seventeenth century, published his  in 1670. [2] The entire chapter 20 of his Prodromo is an exact reproduction of Neri's. Lana Terzi was fascinated by experimentation and manual arts. The Jesuit order refused their members permission to write about magic and alchemy; Jesuits with such esoteric interests could never write books directly devoted to these subjects, however, they could write works on the different aspects of natural philosophy. In this broader context chemical philosophy could be admitted.

Title page of Lana Terzi's Prodromo

Neri was popular in his own time for his glassmaking knowledge. His L'Arte Vetraria  was widely read and its reprints and translations appeared over the centuries. [3] Nevertheless, Neri enjoyed a considerable reputation among his contemporaries also for his 'chemical philosophy'. Discorso is a complete treatise on the subjects of chemistry and philosophy, to all appearance not different from many others written during the sixteenth century. It holds a similar structure, with an introduction defining the subject and the description of procedures. The final part lists possible objections raised against the validity of chemistry and gives Neri's timely responses. In this sense Discorso belongs to the alchemical traditions and Neri shows his deep knowledge of the Paracelsian doctrine and literature. Even so, the main features of the new 'scientific' mindset are present in Neri's treatise: the study of "the great book of nature" and the value of experimental practice. The traditional reliance on the authority of ancient wisdom loses its legitimacy. "We should not so easily give credence to all the histories," Neri claims, but we should "prove the possibility of this art of transmutation with certain […] experiences". Knowledge is acquired "with the practice of many experiences." It does not come from a divine revelation or from the study of many books.
There is no contradiction between the alchemist Neri and the glass-conciatore Neri; the will of gaining a deep knowledge of nature, based on the observation and experimentation, is common to both. Neri is always 'the technician' and never 'the philosopher'. Alchemy, the "Great Art," is the result of a deep study of nature and its aim is not to give an imitation of nature, but to make it perfect.

The 'modernity' of Neri can also be understood in his way of talking about chemical philosophy. He does not pretend to teach eternal truths, but only to indicate the way to achieve greater knowledge, by "understanding the modus operandi of nature." Consequently, the writer does not use the form of a dogmatic essay, but that of a conversational chat, or 'discourse'.

It would be interesting to discover how Lana Terzi came into possession of Neri's manuscript. Perhaps he was attracted by the mixture of old and new which was also a predominant theme of his time, when different models of knowledge coexisted and intertwined. Discorso offered him the chance of introducing the topic of alchemy without being accused of magism.

-M. G. Grazzini

[1] Grazzini 2012.
[2] Lana Terzi 1670.
[3] Neri 1612, 1613.
* this post first appeared here on 20 November 2013.