From the earliest times in the history of glass (Mesopotamia, third millennium BC) there are evidence of opaque or opaque glasses, that is, Shower Enclosure dubai partially transparent or practically non-transparent glasses. Despite the beauty or excellence that such glasses could present, the lack of transparency was not a property neither sought nor intentionally caused by glass craftsmen but was the simple consequence of the lack of technical knowledge, which made it impossible to have furnaces. and glass-making processes that reached the temperature necessary for the raw materials to completely melt and give rise to a transparent glass [1]. For this reason, it can be said that opaque and opaque glasses have existed since ancient times, although they were only the result of an imperfect production procedure, as well as their characteristic greenish tones, mainly caused by the iron impurities of the sands that provide water. silica, since they did not have purification methods for these raw materials. Although the greenish tones were not intended, ancient glassmakers soon added metallic salts or other components to the glass mass in order to obtain colored glasses.
Later, Egyptian culture was a great promoter of glass and the production of objects, generally small, mostly blue and green, which was very abundant. Almost all Egyptian glass is opaque, regardless of the functionality of the object: tableware, jewelry, ornaments, etc., and they also constituted luxury items that imitated the shapes of other containers made with other materials. Around 1100 BC, some creamy white pieces appear, imitating exactly objects made of alabaster. The great variety of colors confirms that the Egyptians already mastered the coloring techniques and that, although they were capable of making somewhat translucent glasses, most of them were still opaque.
In the year 31 before our era, after the rise to power of Augustus and the establishment of the Empire in Rome, the greatest innovation to date took place in the world of glass: the invention of the blowing reed and the glass technique blown. With it, the productive rhythms accelerated. The great variety of colors that can be observed in the objects of this time and the purity that Roman glasses came to reach suggest that glassmakers dominated the techniques of staining, bleaching, and pacification of glass [2]. The composition of Roman glass and those of later periods remained unchanged until the 11th century. . The change in composition arose because soda, aluminium and glass work dubai a flux component of the vitreous mass, became scarce in Central Europe, and glassmakers in these areas replaced this alkali with potash, which they extracted from the ashes of ferns and other forest plants. . Hence, the glass of this time is called forest glass.
In the Renaissance, the supremacy of Muranese glassmakers spread, as did the new classical style for all the arts. In Murano, the quality of the glass was perfected and Cristallo was created, which imitated rock crystal (quartz). The Cristallo was a glass of high purity and very moldable. At the same time, they began to produce a glass, called lattimo or milk-white glass, which emerged as an imitation of the delicate and fine oriental porcelains. The term milk-white derives from the French expression blanc de lait; in England, it was called milk glass, in Germany Milchglas, and in Italy lattimo . The term white glass was used for transparent colorless glass and not for opaque or opaque glasses. Traditionally, these opal glasses were made by adding calcined bone ashes to the composition, although the Venetians obtained them by adding tin oxide [3]. Murano’s influence on European glass lasted until the 18th century when glassmakers in other areas began to be more creative and technically advanced. These were the cases of England, with the invention of lead glass, and of Bohemia, with potassium-based glass [2].
In Spain, the production of milk-white glass decorative objects in the Royal Glass Factory of La Granja began in the last two decades of the 18th century, as a result of the preference shown for this type of glass in Bohemia. At that time the milk-white glass was invariably decorated with enamels depicting gallant scenes, landscapes, or bouquets of flowers, trying to imitate Chinese and German porcelain from Meissen. Generally, this enameled decoration of opal glass used to be combined with fire-gilded motifs [4].
The arrival at La Granja in 1747 of the French master Dionisio Sibert determined the beginning of the production of milky glass, as opal glass was particularly called in the Royal Site, and initially, aluminium maintenance in dubai this white glass was used for the elaboration of objects that were to be decorated. In the Royal Glass Factory, different opacifiers were used to obtain milk-white glass. In 1799 Facundo Diaz de Vargas y Argús explained the two procedures extracted from the recipes in the book Arte Vitraria [5] :
1.
According to the Venetian formulas, by adding tin lime and lead.
2.
By mixing calcined deer bones or horns (calcium phosphate).
