Lot 1108
Treasury 5, no.722 (‘Biotite Sandwiched’)
HK$27,500

Flakes of biotite sandwiched between two layers of transparent sapphire-blue glass suffused with small air bubbles, with much larger irregular air bubbles trapped in the sandwiched layer; with a concave lip and flat foot
1720-1840
Height: 4.92 cm
Mouth/lip: 0.66/1.34 cm
Stopper: jadeite; vinyl collar

Provenance:
Robert Hall (1988)

Published:
Treasury 5, no.722

This is an example of the so-called ‘sandwiched-glass’ group, in which a decoratively prominent and usually predominant layer of colour is contained between two other layers of glass, the upper one transparent to enable the middle layer to be seen. They represent an additional level of complexity in the production process when compared with single-colour glass or glass with fragments rolled into the surface of another colour. They are created by taking a gather of glass of the inner colour on the blow-iron, decorating its surface in some way (here with the addition of rolled-on tiny flakes of biotite) and then adding an outer layer of transparent glass. This further complication of the process made possible a variety of new and intriguing decorative possibilities.

The inclusions here have been identified for us by Heiner Schaefer as biotite - a form of mica that can be ground into tiny flakes and trapped between two layers of glass. If the mica is of coppery or golden colour it is known as biotite, while the silver variety is muscovite. Since biotite was found in the Bavarian forests, the process may have been familiar to Kilian Stumpf, although we cannot be sure that it was used so early in Bavaria. It is also found elsewhere, however, and European glassmakers are the most likely to have been responsible for its introduction to China. In this example, the colour resembles aventurine-glass, but under magnification it becomes evident that the inclusions are a series of discreet flakes. The irregular, rough-edged biotite has created an intriguing effect by trapping large, irregularly shaped air bubbles. If irregular solid flakes of some sort are sprinkled or in some other way introduced onto the surface of a piece of glass that is then cased with another layer of glass, some trapped air is inevitable. The surface tension of the air bubbles has become attracted by the biotite flakes and stretched the air into unusual, jagged shapes, making them even more prominent as the light is reflected from their irregular surfaces.

We believe that cased or overlaid glass of this sort, whether containing a sandwiched layer or not, originated during the Kangxi period. A set of twelve cups presented to the throne in 1708 by Ding Zaobao 丁皂寶 (probably a high-ranking eunuch) appears to have consisted of at least two layers of glass. The carver, a man from Guangzhou named Cheng Xianggui 程向貴, may have been working either at the imperial glassworks or in a separate facility run by Ding Zaobao—the latter possibility is suggested by the facts that 1) Ding had an uncarved set made by another Guangdong craftsman that he didn’t present to the throne until 1724, and 2) when a query came down in late 1725 as to the particulars of the production of the two sets of cups, only Ding Zaobao knew that the two glassworkers had returned to Guangdong in 1715. On a glassworks run by a contemporary prince, see Sale 3, lot 100.

It is possible that bottles of this type were made throughout the dynasty and into the Republican period, although the vast majority are likely to be eighteenth century or early nineteenth, if for no other reason than this was the time of greatest demand for snuff bottles and the greatest extent of their manufacture.

This lovely, simply shaped and elegant bottle is probably of the eighteenth century, and possibly from the first half, although we have allowed a broader possible dating range in view of our uncertainty regarding when the use of biotite was incorporated into Chinese glass technology. As with so many fine glass bottles, the imperial glassworks remains a likely source, since this type of sandwiched glass was apparently a staple there, but without a clearer picture of what was produced elsewhere as well, we have resisted making an attribution.

This is not the Sotheby’s sale catalogue. This is a product of Hugh Moss for the purposes of this website. For the catalogue details please refer to Sotheby’s website or request a copy of a printed sale catalogue from Sotheby’s.