: Mike,

: What is your basis for these two comments? What do you consider
: "proper" wet out? All of the micrographs and fiber
: descriptions I'm familiar with indicate that glass, carbon, and
: aramid fibers have the same shape - right circular cylinders.
: Therefore, if we take "proper" wet out to mean either
: an optimum fiber/resin volume ratio, or a common fiber/resin
: volume ratio, then the chemical composition of the fibers should
: be irrelevant.

While that's true in theory, it's somewhat different in practice. Carbon fiber tends to lay much thinner than Kevlar, probably because the stiff fibers stay in relatively tight contact as they weave around each other. Kevlar fibers are softer and more bulky, which creates more air spaces in the weave that will ultimately be filled with resin when laid up. Kevlar is also buoyant and will readily float on top of the resin. The upshot of this is that in order to keep the fiber-to-resin ratio near optimum, you need to compress Kevlar more than you do carbon fiber. Vacuum bagging, resin infusion, packing tape or some other compression method will compact the fibers and reduce the space in the weave for resin, reducing the weight and improving the strength of the layup.