Among man's inanimate servants, glass occupies one of the highest ranks: it is everywhere: in the cellar, in the garden, in the kitchen, in the living room, in the toilet; it is used for everything: for drinking, for lighting, for sheltering, for enlarging objects, for reproducing them; it renders almost every service to us, not counting those that we do not admit.
It is easy to understand how varied its display can be.
It goes, in fact, from the vulgar green or black bottle, of which the Richarme factories showed a curious and very complete collection, to the diamond, imitated to a fault, which is exhibited by a factory of fine glasses, used especially for optics. Let's talk about the latter.
Depending on the instrument, optics requires very dense or, on the contrary, very light lenses of a particular manufacture. These special lenses, made of the finest materials, are called crown glass or flint glass. They have all the appearance and qualities of natural crystal, known as rock crystal, combined with dimensions that the latter cannot achieve. Thus, we are shown here a crown glass lens, lm,05 in diameter. It is the largest ever made, and is intended for the Spence Observatory telescope, built at the expense of the University of Southern California.
Flint is used mainly for plane mirrors, or prisms.
There is not much to be said for window glass, as nothing resembles a window so much as a window like it. Stained glass windows are nowadays in great favour and are consumed to a considerable extent, only as they are expensive, they are quite generally replaced by simple panes of enamelled glass with designs. This arrangement, which is obtained by the application of an enamel on the white glass, gives pretty results.
It is known that, despite the progress of glassmaking, thin glass has not yet been cast and, above all, not cheaply. We shall see that Saint-Gobain is moving in this direction. In the meantime, we are still at the blowing stage, which is currently done either by mouth or by compressed air. It is to blowing that we owe, not only the bottles, but also the glass and the sleeves which are either kept in sleeves called cylinders, for clocks and other objects to be sheltered, or split, extended and annealed for the manufacture of glass.
Watch glasses are also blown. This means that a huge ball, such as the one shown in the middle of the gallery, is blown and watch glasses are cut out of the ball, giving them a slight convexity.
The mirrors are technically cast glass, which distinguishes them from blown glass. Commercial mirrors, in the low price range, are usually only made of double tinned or silvered glass, although they are decorated with the name of mirrors.
The leading organisation in the world for the manufacture of mirrors is the Société des manufactures des glaces et produits chimiques de Saint-Gobain, Chauny et Cirey.
It is a national industry, although it is owned by a limited company. Founded in 1665, on a report from Colbert, to whom we must almost always trace the creation of our great industries, it inaugurated, in 1691, the casting of ice invented by Louis Lucas de Nehou. It is clear that the company has been in existence for 224 years.
In the middle of the gallery, the exhibition includes a magnificent mirror, i.e. one that is intended to be silvered, measuring 7.63m by 4.10m and weighing 938 kilograms. This mirror comes from Chauny. It is accompanied by a series of silvered and non-silvered mirrors and glazed mirrors that exceed the largest dimensions achieved to date. But the most important piece is a window of 8m,14 by 4m,20 which closes a window of class 21. A piece this large has never been produced before.
Saint-Gobain sent one measuring 8.10m by 4.14m, but this one is raw, i.e. it has not yet undergone any of the operations which should give it a polished finish and make it either a window or a mirror. These operations are shown to us in a series of small mirrors which are :
The first, rough, that is to say such as it is provided by the cast iron, in this state, it is grooved and as if sandblasted on one of its faces.
The second is roughened by rubbing with sand.
Then it is soaped with emery, and in this state it resembles what Ton calls frosted glass.
Finally, polished with iron peroxide, it is ready to be silvered by the reaction of tartaric acid with nitrate of
tartaric acid on the silver nitrate. Silver plating replaced mercury plating, which was deadly for the workers.
Saint-Gobain has sought and found many applications for molten glass over the years. For example, the company's factories manufacture polished slabs that can be used as a front for money changers, jewellers and goldsmiths, and, thanks to their resistance, can be used without another closure. There are also headlight and optical parts, represented by a mirror that weighs 600 kilograms.
In the thin glasses mentioned above, we have not yet managed to obtain a polished finish, and we have to be content with replacing the frosted glasses with granulated, fluted or diamond-shaped glasses. They are much more resistant than frosted glass and are less expensive.
For paving, which must allow light to pass through, either tiles with reliefs or simply rough tiles are made. Finally, when a passageway needs to be covered so that cars can drive through and yet light is required, glass blocks can be used, which are 15 centimetres thick and which, when placed on an iron in 1, can withstand any pressure.
Finally, Saint-Gobain glass is used to make wall coverings for hospitals, guttering, communal seats, urinals, and tiles which have the advantage of stopping air and rain while letting light through.
With Saint-Gobain, we have seen just about every industrial application for glass. Now it is being used as a tableware. It is still the beautiful white crystal, cut or engraved, which holds the first rank, and it is not ready to be abandoned, however successful the fancy services imitating either the Venice or the Bohemian may be.
The Middle Ages disease from which French taste suffered some time ago, has left its traces in enamelled glasses which are, my faith, charming in their forms and decorations.
Add to this a large number of goblets, candelabras and chandeliers and you will have a general idea of the glass exhibition.
But what you won't find anywhere is the reason why there is no Baccarat exhibition. I asked everyone about it and no one answered me.
It is, it seems, the secret of the gods.
©Livre d'Or de l'Exposition - Paul Le Jeinisel.