To overcome this problem, glass reinforcements are treated with 'coupling agents' which combine chemically with both glass and resin, and hence result in good adhesion at the glass-resin interface. These coupling agents are called either 'sizes' or 'finishes' according to whether they are applied as the fibers are drawn or after the fabric has been woven. The high-performance sizes and finishes are optimized to the chemistry of a particular family of resins. Hence, a fabric, once finished with a given coupling agent, will be compatible with only a restricted class of resins. Kevlar fabrics are ordinarily furnished 'scoured' rather than finished with a coupling agent.
Scoured fabrics are compatible with all resin systems.
The Kevlars we sell are classified as industrial grade. The frequency of defects tends to be very low but erratic. To minimize the likelihood that defects will be of concern to you, we fully inspect these materials, and, in the process, remove defective segments of the fabric or send this fabric to you as extra at no charge. In most cases the industrial grade Kevlar is typically much like first-quality material, but at a lower cost to you.