Knowing and understanding the glass techniques employed by Murano glassmakers is vital to successful collecting and dealing, as well as learning the related terminology in both Italian and your native language, as many Murano glass resources are only published in Italian. My goal with this series of articles is to showcase numerous glass techniques that were used on Murano, with a focus on the twentieth century. Sometimes, certain glass techniques were only used by a single glassblower, or a very small number, because they were so difficult to execute, so being able to recognize them can help with identification. More commonly, the talent of individual glassblowers on Murano was very, very high, so most glass techniques were replicated at all or most glass furnaces on the Island. With that, quality of execution can vary widely between individual glassblowers and houses, so understanding what attributes contribute to a more successful execution is also important and, once again, can help you in identification. In this article, I will discuss the techniques of Incamiciato and Sommerso, how they relate, and how they are different, as well as to offer comments regarding the research of these two glass décor types.
Incamiciato, translating to jacketed, encased, and layered, refers to the thin layering of glass onto a base layer. In American glass terminology, it is referred to as glass casing or cased glass. During the pre-war time period on Murano, to obtain the look of opaque colored glass, it was common for the glassblower to overlay a thin layer of colored transparent glass atop lattimo (milky white) glass. This general décor type is also referred to as doublé. The alternative of thin casing transparent over opaque glass was to use pasta vitrea glass, which is non-cased opaque glass that contains a large quantity of opacifies and pitments. These additives made the glass type incredibly difficult to work with, particularly on the back end with the very long cooling times it required. During this period, very few glass furnaces on Murano had the technical skill to execute with pasta vitrea glass, so many simply opted for thin casing method described above, as it still provided the opaque look and the results were more predictable. Additionally, an object can be cased in a very thin layer of transparent glass to smooth the surface or to protect any internal decoration, such as the application of metal foils.
Sommerso, translating to submerged, is where a thick layer of glass is overlaid atop another layer of glass, generally of a differing color or glass décor type. The technique can employ two layers of glass or numerous layers, but one single layer of thick glass does not meet the criteria of the sommerso technique. You will also hear individuals use the term thick casing, which is the same as sommerso. When people hear the term sommerso, they generally think of the even, symmetrical execution of one transparent color over another transparent color. This variant of the sommerso technique was made very popular during the Mid-Century time period by Flavio Poli at Seguso Vetri d’Arte, but was offered in numerous glass-producing regions at the time, and today is produced the world over.
A related term is induto, which is interchangeable with sommerso and, again, is where any glass décor type is covered with another thick layer of glass. For posterity, one would not use the term induto when discussing a piece with multiple layers of transparent glass, like the above example. For that, you would simply use the term sommerso. Examples of induto include pulegoso induto, which is where pulegoso (frothy irregular bubbles) glass is submerged in another layer of thick glass, often clear. Continually, gold leaf is frequently incorporated, making the descriptor pulegoso oro induto. This indicates the object utilizes pulegoso glass with gold leaf added to the surface and then the entire mass is submerged in a thick layer of glass. Sometimes, the furnace will indicate cristallo for crystal, but if it simply states induto it can be assumed that a thick layer of clear glass is intended. An interchangeable term for pulegoso is bollicine. Common use of these terms includes sommerso a bollicine, or bollicine induto, but both mean the same thing, a layer of pulegoso/bollicine glass submerged in another layer of glass. Sommerso glass objects can also have a purposeful uneven surface and feature undulations, ribbing, and any sort of molded or hand-tooled surface texture.
Continually, in a furnace’s documentation, there may only be a singular note of bollicine paired with a drawing of a piece with irregular bubbles inside of what appears to be a thick layer of presumably clear glass. The glassblower knows that the desire is to submerge pulegoso glass in a thick layer of clear glass, because of the glass series they are working on. When researching, the reader should use all available context clues, such as the décor types popular at the time, historical information about the furnace, the designer’s preferences, and so on, to determine what exactly is meant by the notations and the illustration. To continue, many furnaces offered various décor types in the same model number. The drawing could picture irregular bubbles cased in clear glass, but you could reasonably see multiple layers of bullicante glass cased in thick green glass, with one or both variations internally decorated with gold leaf. Being able to recognize glass décor types, colors, and shapes produced by each furnace will enable you to identify objects more readily and with greater confidence. Researching glass can be very difficult and oftentimes the answer is not in clear black and white in front of you, but rather a mixture of resources and experience.
It should be mentioned that glass term usage varies by furnace and by glassblower. Some furnaces did not use particular terms and opted for a different one with the same meaning. When describing a piece, it would be more correct in your description to use the particular terms that were utilized by that particular furnace.
In summary, incamiciato refers to the thin layering of glass and the term sommerso refers to the thick layering of glass. There are numerous variations of each, and the terms associated can vary widely depending on the original source, or the collector and dealer today.
