“There are several advantages to using a prepreg rather than using traditional hand layup…
Maximum strength properties. In a hand layup, it is difficult to achieve 50% resin content. This means that the finished laminate weight is 50% fabric and 50% resin. Typical hand laminates, even when vacuum bagged, end up with a significant amount of excess resin. Excess resin increases brittleness and reduces overall properties. On the other hand, most prepregs contain around 35% resin. This is ideal for maximum cured properties and generally impossible to achieve in normal hand lamination.
Part uniformity and repeatability. Without the pitfalls of human lamination techniques, there will be neither resin-rich areas nor dry spots. Thickness will be uniform and every part that comes out of the mold has a theoretical likelihood of being identical. There is still a margin for error in vacuum bagging techniques, handling, etc., but prepregs reduce these problems significantly.
Less mess and less waste. Prepregs will bleed excess resin during the curing process but all of the excesses of hand layup – cups of resin, messy rollers, drips – are no longer a problem. Plus Fibre Carbon prepregs are handled at room temperature so you are not fighting a clock trying to avoid your resin setting up before you are ready.
Less curing time. After the heat curing cycle is completed, the part is ready for service. You do not have to wait the standard 48 hours to allow a full cure as in a typical hand lamination.
Better cosmetics. Mold preparation and mold release is still required and will directly affect the cosmetics of the part just like a hand laminate. However, Fibre Carbon prepregs virtually eliminate air bubbles and a smooth, glossy surface is more easily attainable.