Stone that flows: Illuminating the world of pate de verre

The French kiln glass technique pate de verre is among my personal favourite categories of Art Nouveau glass. With its distinctive malleable aesthetic and soft colouring, often processing a subtle luminous glow, it most certainly conveys the epithet coined by the Egyptians, ‘stone that flows’.

I remember holding a Gabriel Argy Rousseau pate de verre vase for the first time and marvelling at his mastery over this seemingly unmalleable and unforgiving material. His work along with that of his peers suggests the contrary and so prompting my curiosity into this obscure art form.

Since the Art Nouveau movement of the late 19^th Century, artists have incorporated pate de verre into everything from simple platter-like forms to vessels, interiors including windows, mosaics, chandeliers and lamps, and sculpture, objet, and jewellery.

Pate de verre, meaning ‘glass paste’ is a highly valued and revered category of art glass not only because of its arduous, time consuming processes, but the expertise and artistry required to master it. Throughout history it has been associated with the elite, as a symbol of wealth, taste, and luxury.

Like most forms of art glass there is a mystique that enshrouds the pate de verre technique; most of the time we see its finished outcome without fully understanding the creative process. Thus, in the following I have tried my best to explain and break down the journey from glass paste to object.

1. Pate de verre incorporates the technique ‘cire perdue’ or lost wax method. The technique uses a mould taken from a wax model.
2. The completed wax model is firstly cast in a non-flammable material such as plaster to create a negative mould before being destroyed and melted away.
3. Ground glass (known as frit) is mixed with gum Arabic and water, and often pigments and enamels to form a paste. Sections of the mould that eventually stand out in relief are filled in first, then the background of different colours is added to a thickness of several millimetres.
4. The centre of the mould is filled in some way to prevent the paste from slumping (back in the day Argy Rousseau used powdered asbestos!). The kiln firing fuses the glass together under a very high temperature (approx. 800 C).
5. The piece takes numerous days to cool before it can be removed from the mould.
6. It is then carefully cleaned and polished, or further work can be done such as engraving or etching.

Kiln glass production is ancient; it dates to 3500 BCE when Mesopotamians were found to have documented their techniques in cuneiform texts, the Egyptians and the Romans were known for practicing kiln glass too. After this period in history it appears to have languished in obscurity until its renaissance in the late 19^th Century.

It was the masters of the French Art Nouveau movement who resurrected these techniques and coined the expression pate de verre. They also revived other ancient forms of art glass like cameo glass. With the help of technologies from the industrial revolution, artists were able to develop their practices to a high level of artistry and volume of production. There are many artists to acknowledge including the Gabriel Argy-Rousseau, Henry and Jean Cros, Albert Dammouse, Francois Decorchemont, Amalric Walter, Emile Galle and Georges Despret.

The large-scale production of pate de verre lost its momentum again after the second World War and since then transitioned to the studio movement of the second half of the 20^th Century. To this day, original Art Nouveau pate de verre remains highly distinctive and coveted for its quality and artistry. It serves as a testament to how Art Nouveau reignited the world’s adoration for the forgotten practice of kiln glass, fusing the ancient with modernity and reminding us of the creative potential and versatility of glass.

Dominic Kavanagh, Decorative Arts Specialist
30 September, 2020