Mineral Wool and Glass Wool Information
Mineral wool and glass wool are fiber materials made from slag, rock, glass, and minerals that have been melted and spun into filaments. The fibers that comprise mineral wool, rock wool, slag wool, and glass wool are collectively known by a variety of terms, including synthetic vitreous fibers (SVF), man-made mineral fibers (MMMF), and man-made vitreous fibers (MMVF).
Despite differences in exact fiber types, the wool types above share common applications based on the characteristics listed below. These qualities are often combined into a single product; for example, mineral wool batt insulation may be installed in a building to provide thermal insulation, acoustic protection, and fire protection.
Thermal insulation—Mineral wool, slag wool, and glass wool make excellent thermal insulators due to their intertwined fibers that form low-density air cells within the material. Insulation may be produced as loose-fill material for insulating flat surfaces, or batts for ceilings, attics, and ducting.
Types of Mineral Wool and Glass Wool
A wool's type is determined by the fibers or filament used during manufacturing. The table below compares the characteristics of stone wool (a type of mineral wool) and glass wool.
|
Type |
Description |
Fiber length |
Pressure resistance |
Maximum working temperature |
Elasticity |
Melting temperature |
Fire resistance |
Tensile strength |
Image |
|
Stone wool |
Made of volcanic basalt or dolomite, or sometimes slag |
Short |
High |
~750° C |
Low |
Over 1000° C |
Superior |
Low |
|
|
Glass wool |
Made of sand, limestone, and soda ash |
Long |
Lower |
~230° C |
High |
~700° C |
High |
High |
|
Production
Production of mineral and glass wool is nearly identical save for the difference in raw materials.
- Raw materials (stone, glass, slag, or sand) are first sent through a furnace and melted at very high temperatures.
- Melted droplets drop through the furnace and are spun into fibers. Depending on the materials, spinning is accomplished by rotating flywheels or spinners.
- Binders are then added to the fibers, and a curing oven heats them at moderately high temperatures. The binder reacts to the heat, forming the fibers into wool.
- Cutters shape the material into rolls, batts, or boards, with cut scraps recycled back into the production process.
The video below illustrates a typical mineral wool manufacturing process.
Video credit: ROXUL Inc.
Standards
Mineral wool insulation may conform to production specifications laid out in published standards, including ASTM C726 and BS EN 13162. Additional standards can be found at the Engineering360 Standards Library.
Resources
Eurima—Mineral/Glass Wool Production Process
Image credits:
Technical Glass Products, Inc. | Knauf Insulation (both images in table)