Fiberglass reinforcement materials are a pretty complicated subject and hopefully we can keep it clear. There has been all sorts of nomenclature developed over the years to describe the different weights and styles.

When we talk about fiberglass we are really talking about fibers of glass. For the reinforcements we are discussing, they are bundled together to form larger, more workable bundles.

Roving is a ball of continuous filaments wound into a 40 to 5o pound ball. This is commonly used in the fabrication shop with chopper guns and filament winding equipment.

Chopped Strand Mat is the most basic reinforcing materials that comes as a sheet good on a roll. It is fiberglass that is chopped into small pieces and mixed with a binding material to hold it together, before being randomly oriented into a continuous mat.

Continuous Filament Mat uses a continuous fiber nonwoven to itself and contains some sort of binder material. I have also worked with some continuous filament mat that is stitched together to omit the binder.

Surfacing Veils are a non stitched mat product that use very fine glass fibers in random orientation to assist with achieving an improved surface finish. They are intended to keep the coarse fibers away from the gelcoated surface to prevent print-thru.

Woven Roving (Knytex) is a very diverse product that is widely used throughout many applications and processes. It consists of continuous rovings woven in specific directions to each other and then sewn to a Chopped Strand Mat with thread. They come in hundreds of different combinations of directions; including unidirectional, bidirectional, triaxial, and quadriaxial. The Chopped Strand Mat also comes in different weights and sometimes may be substituted with Continuous Filament Mat.