All glass fiber products require some form of sizing, or finish, to be applied to the glass. The finish serves two purposes: 1) to lubricate and protect the fibers from fracture during processing, and 2) to interface with the end use application providing good chemical compatibility with the resin or chemical coating that is subsequently applied.

In conventional fabrics, fibers are drawn from molten glass and a starch-oil sizing is applied. This sizing provides mechanical integrity and lubrication for subsequent processing. Warp yarns, corresponding to the grain direction in the laminate, are then coated with an second sizing for additional protection. The sizing applied to the glass fibers is subsequently removed by a thermal decomposition process and the fabric is coated with a silane finish to provide a chemical coupling between the glass surface and the resin matrix.

Therefore, the traditional sizing and finish application requires the following steps:

1. Starch-oil sizing is applied when glass fibers are formed;

2. A second protective finish is applied to the warp yarns;

3. After weaving, both finishes are removed via a thermal decomposition process (700°F for ~3 days);

4. A silane coupling agent is applied that is compatible with the laminate resin material.