Preface

Like the 2016 electronic resource The Techniques of Renaissance Venetian Glassworking, this e-book presents my thoughts about how a selection of historical glass objects may have been made some 300 to 500 years ago. In this second publication, I consider glass of a similar style and period that was made in a wide variety of European locations other than Venice (Fig. 1). The craftsmen may have been itinerant Venetians or perhaps local craftsmen who had been trained by skilled Venetians, or a combination of the two.

The videos that are the centerpiece of this publication represent one highly personalized way of re-creating the original blown glass objects—or, more correctly, re-creating the processes by which I think they were made. Here, as in all of my historical re-creative work, my intention is to focus on generating information rather than simply making objects.

My working methodology is straightforward.³ First, I closely examine the original piece in question. If possible, this is done with the object “in hand.” I seek parallel objects to look for common features and differences within the type or genre. Any specific evidence of the manufacturing process is noted. This would include such things as toolmarks, the distortion of bubbles trapped in the walls, and patterns of variation in the wall thickness of the glass. In short, I look for anything that can shed light on the order of operations and subtle manipulations that the glassblower employed hundreds of years ago.

Next, I offer several hypotheses as to how the object could have been made. The many options are narrowed by my accumulated experience of working with molten glass and by my curiosity about historical glass for well over 50 years (Fig. 7). I try to consider any reasonable possibilities.

By contrast, my equipment setup, together with my strictly adhered-to choreography (as can be seen in the videos), allows me to comfortably execute all of the required procedures entirely without assistance. While I make no claim that this approach is true to the period, I am confident that the action that takes place at the ends of the blowpipes and punties is very much like what took place in a Renaissance Venetian or Venetian-style glasshouse.

Similarly, the glass that I use is not formulated to closely replicate old Venetian glass, but it is nevertheless a long-working soda-lime glass that is probably not terribly different in temperature/viscosity characteristics from the glass that was employed by those earlier artisans.

The furnace seen in the videos (the original version of which I built with a colleague in 1981) is of the type known as a pot furnace, fired with forced air and natural gas (methane). During the manufacturing process, like the workers depicted in the Butteri painting, I reheat the object directly over a ceramic crucible filled with molten glass contained within the furnace. Thanks to its great thermal mass, this promotes a uniform source of radiant heat in addition to the voluminous hot gases that, swirling about, also heat the object by conduction—that is, by direct contact. In sharp contrast, a wood-fired furnace creates a much smaller volume of gaseous products of combustion: here, the gentler heat source necessitates reheating durations that are up to twice as long as those required for the same processes in a modern, gas-fired furnace (Figs. 9 and 10). Lastly, working directly over the glass facilitates the frequent gathering of additional glass for the many parts of complex objects, such as dragon-stem goblets: the molten glass is always just an arm’s reach away.