Glasstrekk

Glasstrekk is the industrial process of drawing molten glass into continuous filaments or fibers. The term covers methods used to create thin glass strands for a range of applications, including reinforcement in composites, thermal and acoustic insulation, filtration media, and specialty fibers. The process relies on forming molten glass and pulling or drawing it through small orifices to achieve controlled diameters and mechanical properties.

In typical glasstrekk operations, glass is heated in a furnace to a viscous state and extruded through bushings or orifices. The incoming stream is drawn by mechanical rollers or by air-jet forces, with draw speed, viscosity, and temperature carefully controlled. The resulting fibers may be collected as rovings, wound onto spools, or further processed into yarns or mats. For optical fibers, even stricter control of composition, refractive index, and diameter is required, often involving high-purity silica and specialized drawing towers.

Materials used include soda-lime and borosilicate glasses for general fiberglass products, as well as high-purity silica for optical and specialty fibers. The resulting products range from fiberglass for composites and insulation to fine optical fibers and other high-strength glass filaments. The process emphasizes uniform diameter and surface quality to ensure predictable strength and performance.

Quality considerations include monitoring viscosity, temperature, and draw tension to avoid beads, breaks, or diameter nonuniformities. Safety concerns involve inhalation of fiberglass dust and skin or eye irritation; appropriate protective equipment and containment are standard in glasstrekk facilities. The technique is central to modern glass-fiber technology and related industries.