Fiberglas is the trade name of a product of Owens-Corning Fiberglas Corporation and is defined in their literature as follows:
"Basically, fiberglas is glass. Matter of fact, it is made in much the same manner as most glass. A number of finely pulverized ingredients, including sand, lime, and metallic oxides, are mixed in appropriate proportions and melted in a giant furnace. When the melting is completed, the mass is fused into a substance, glass, which is a complicated mixture of silicates, with no free silica present. The specific gravity is approximately 2.54. The molten glass is drawn out into slender, thread-like fibers. These flexible textile fibers look and feel like silk; the finest of them are almost invisible."
In a personal communication from the corporation's technical consultant it is stated: "The filaments are formed... for textile yarns by drawing slender filaments mechanically by means of rapidly revolving drums upon which
GAINES TR. Fiberglas in the Eye. AMA Arch Ophthalmol. 1958;60(5):941-944. doi:10.1001/archopht.1958.00940080961014