Check out the picture above.
First, from the left, fiberglass in the form of continuous roving filaments, or fiber bundles, is drawn though the liquid resin, which saturates the glass reinforcement. Next, this combination of resin and glass is then pulled through a special die using a continuous pulling device (hence the name pultrusion for pulling through, rather than extrusion which is pushed through).
The resulting high-strength profile is cut to length -- ready for use when it leaves the pultrusion machine.
Pultruded products provide manufacturers and designers with the benefits of high strength-to-weight ratios, corrosion resistance, heat resistance, dielectric properties, dimensional stability and weatherability. In the end, pultruded products are a cost effective and versatile alternative to traditional materials.
Here is 48" wide sheet being pultruded...
The fiberglass material is typically produced in 3 grades:
1. Standard with isopthalic polyester resin and various layers of fiberglass roving and mat.
2. Fire Retardant and UV resistant chemicals added to the Standard Grade
3. Vinyl Ester Resin, FR and UV additives - for extreme chemical resistance.
Standard colors are Green, Gray, and Beige respectively. Any color can be run if the quantity is high enough.
A short list of pultruded products in the marketplace: Tool handles, ladder sides, skateboard decks, fiberglass stairs and platform systems, fiberglass grating, fiberglass decking, u-channel, I-Beams, structural profiles of all sorts. Photos: (courtesy of Liberty Pultrusions)