When carbon-fiber composites are cut, fibers are exposed. These fibers can absorb water, which both weakens the material and adds weight to the structure. Sealants can prevent moisture absorption, but this both complicates the process and adds cost. It also defeats any effort made to maintain electrical continuity between the composite fibers and the fasteners. Sleeved fasteners can provide fits that reduce water absorption, as well as provide fuel tightness.