Forgefix twist nails sheradised forgefix 500nlt30sb these forgefix twist nails are a unique twisted shank nail for attaching metal work joists hangers straps etc the twisted shank assists in absorbing movement that may occur in construction they have a sheradised finish for corrosion resistance this finish is a thermal diffusion process in which zinc powder is vaporised and diffuses to the surface of the twist nail to form a sacrificial corrosion protective zinciron alloy coating thus