An emerald-green and sapphire-blue glass overlay snuff bottle
1730-1780 6.35cm high.
Treasury 5, no. 977
A two-colour glass overlay snuff bottle
Transparent brown-streaked emerald-green, sapphire blue, and colourless glass suffused with air bubbles of various sizes, many elongated; with a flat lip and flat foot; the single plane of overlay colours uncarved 1730-1780 Height: 6.35 cm Mouth/lip: 0.91/1.83 cm Stopper: tourmaline; vinyl collar
Condition: A few short grooves in the outer neck where bubbles are cut through, but not subsequent damage; workshop condition
Provenance: Sotheby's, London, 2 May 1985, lot 373
Exhibited: Sydney L. Moss Ltd., London, October 1987 Creditanstalt, Vienna, May-June 1993
This is a rare example in which the carving of the overlay was never completed. The bottle offers some intriguing insights into the production process. The colourless glass ground was finished by the lapidary before the overlay colours were applied. The finish of this ground is so perfect, even beneath the thin, drawn 'threads' of glass remaining when the tool was removed from the molten overlay, that it cannot have been done afterwards. Apart from the evidence of this immaculate ground plane, one or two air bubbles have been cut through at the surface. Each one of these has left a hemispherical depression, one of which is on the body of the bottle, as opposed to the lip. Cut air bubbles are most commonly found on the lip, because the lapidary has to cut right through the ground colour to flatten the lip, and if air bubbles are present in any quantity, the chance of cutting through one or two of them is high. A cut surface bubble would not occur naturally on a freely blown glass vessel, since the air would remain trapped beneath the surface or, if it did burst, the molten glass would naturally fill the space and render the surface smooth once more. Such cut air bubbles at the surface are thus a sure indication of surface grinding and polishing.
We can also see that the inner bottle was blown, while the outer colours were laid on like icing. Many air bubbles in the ground plane here are elongated, stretching away from the energy of the blow iron, whereas the orientation of the elongated air bubbles in the overlay colour is random, offering no evidence of the use of the blow iron. Any manipulation of molten, bubble-suffused glass may elongate the air bubbles, and as molten glass was applied to the surface of the polished colourless glass bottle, it was manipulated. This included being stretched in order to cover the required area and bond completely with the colourless glass beneath.
The difference between a natural fire polish and a lapidary polish is demonstrated here, since the overlay colours display the fire polish, while the ground is a lapidary polish. Signs indicating a fire polish include the natural undulations of the surface of the overlay colours and a pattern of swirls on the surface, visible under magnification.