How to Distinguish Between Different Types of Fiberglass Yarn

Classification by Alkali Metal Oxide Content
This is the primary classification criterion, as it directly determines the yarn's performance:

Alkali-free yarn (E-glass): Alkali content <0.5%. It offers high strength and excellent electrical insulation; it is resistant to breaking under tension and has virtually no surface fuzz. It is primarily used for electronic insulation and high-end fiberglass-reinforced applications.
Medium-alkali yarn (C-glass): Alkali content 8%–12%. It offers good acid resistance and low cost. While its toughness under tension is lower than that of alkali-free yarn and it exhibits slight surface fuzz, it is widely used for anti-corrosion filtration and the production of standard fiberglass fabrics.
High-alkali yarn: Alkali content >12%. It has extremely low strength and breaks easily under slight tension; the surface is covered with protruding fuzz. Considered an inferior product subject to national usage restrictions, it is suitable only for simple waterproofing or wrapping materials.

 

Classification by Filament Diameter
Different thicknesses suit different applications:

3–10 μm (Textile grade): Fine and soft yarn; used for weaving fiberglass fabrics, insect screens, and protective textiles.
10–14 μm: Relatively coarse and stiff yarn; primarily used to produce rovings and chopped strand mats, suitable for composite material reinforcement.
Above 14 μm: Coarse fibers; used only for low-end thermal insulation and filler products.

 

Classification by Physical Form
Distinguishable by the naked eye:

Continuous yarn: Long filaments of indefinite length tightly wound onto a bobbin; the surface is smooth. Used in textile weaving and filament winding processes.
Chopped yarn: Short fibers (3–50 mm in length) with a fluffy, flocculent appearance; used for modified plastics and cement reinforcement.
Bulked yarn: Yarn that has been expanded by airflow to create a fluffy volume with exposed fibers; primarily used for thermal insulation and sealing materials.