The origins
Manufacturing
Forming
Sizing
Characteristics
Glass filament product identification (iso-standards)
The general advantage
of Glass strands
The general advantage
of composites reinforcemend with
Glass strands
Soon after the Egyptians mastered the manufacture of glass, resistant to wear through centuries but fragile in the mass, they discovered the virtues of glass filament. Strong enough to "reinforce" the vases and amphorae found in the tombs of the Pharaohs. A product of human intelligence, the first artificial filament was born.
Tiberius and the Roman Empire, Murano and the Italian Renaissance, Réaumur and the Siècle des Lumières, then Napoleon and the pre-industrial era : from one age to another, glass strand has spanned the millennia, to occupy at last its rightful place in our high-tech century. Thanks to the Saint-Gobain group of companies -heir of the famous Manufacture Royale des Glaces created by Colbert in 1665 and bearer of three centuries of glass-making tradition- Europe began to set up its own production facilities in 1938.





The manufacture of glass is carried out in a special furnace at about 1550°C (E glass) using finely ground raw materials from carefully selected quarries.
The glass leaving the furnace at a very high temperature is used to feed bushings (blocks pierced with hundreds of holes) of platinum alloy.
The majority of Saint-Gobain Vetrotex products are based on E glass. Other glasses are also used, for example R glass (high mechanical performance), D glass (high dielectric performance), AR glass (Alkali and corrosion resistant glass).

The basic strand is made by forming. Forming is achieved by drawing the molten glass flowing from the holes of the bushing at high speed. This forms to between 50 and several hundred filaments. These filaments are defined by their diameters: from 5 to 13 microns (1µm = 1/1000 mm).

The individual filaments of Saint-Gobain Vetrotex reinforcements receive a coating of size at the forming stage, immediately after they leave the bushing. This size, made up of organic products dispersed in water, is designed to give the glass strand certain characteristics necessary for the end application. For textile applications, sizes are generally starch/oil based. For some applications, special sizes can usually contain other film formers than starch and a silane type chemical "coupling agent" which contributes to enhancing the mechanical and ageing properties of the end product.
Saint-Gobain Vetrotex products are either manufactured immediately after they leave the bushing (direct roving) or made up of basic strands subjected to finishing operations which are more or less complicated (twisting for yarns, plying, texturizing, assembly of rovings, chopping of strands and warping).