An explanation of the different fiberglass types used in surfboard construction
4 oz. E fiberglass cloth is the most common cloth used to glass a surfboard. E-glass is easy to wet our with polyester or epoxy resin and laps around the rails easily. If you want the lightest weight surfboard the common layup is 2 layers 4 oz. E cloth on the deck and 1 layer 4 oz. E cloth on the bottom. Surfboards made with all 4 oz. fiberglass cloth are light but not the strongest...
6 oz. fiberglass cloth is typically used in Longboards, eggs, and fish type surfboards. 6 oz. fiberglass cloth is stonger than 4 oz. cloth but of course heavier... It is common to glass a surfboard with a combination of 4 oz and 6 oz. fiberglass. A good, strong glassing schedule is 6/4 deck and a 6 oz. bottom for fish and eggs. Longboards are usually laminated entirely with 6 oz. fiberglass cloth.
4 oz. S-2 fiberglass cloth is rated 20% stronger than standard E glass. S-glass strands are produced at higher temperatures and require more expensive machinery therefore the cost is a bit more. S-glass is a bit "stiffer" than E glass or WARP glass but laps around rails fairly easily. Laminating a surfboard with S-2 fiberglass cloth will greatly decrease heel dents and dings if glassed on the deck wrapping the rails.
WARP glass has more fiberglass strands running lengthwise (parallel to the stringer) providing more break and buckle strength in the board. WARP glass also holds color laminations very well due to the increased amount of glass managing the pigment or tint spread.
Volan cloth is primarily used for old school longboards for it's greenish "Coke Bottle" Volan tint and heavier weight. It's also used in making Volan fins - great flex properties