Two-part adhesive

The proportion of resin to hardener, by weight or by volume, specified by the manufacturer for a two-part system. Because the components react stoichiometrically, deviating from the stated ratio leaves unreacted material in the joint and permanently degrades the cure; it must never be used as a way to speed or slow curing.

The length of time a mixed, reactive resin or adhesive remains usable in the mixing vessel before it thickens beyond application. Pot life shortens as temperature and mixed quantity increase, because the curing reaction generates its own heat.

The component of a two-part resin or adhesive system that reacts chemically with the base resin to build the cured polymer network. Unlike a catalyst it is consumed in the reaction and must be dosed at the manufacturer's stated mix ratio; amines and anhydrides are common hardeners for epoxies.

An adhesive designed to carry significant service loads as part of an engineered joint, transferring stress between substrates over the whole bonded area rather than at discrete fasteners. Epoxies, polyurethanes and methacrylates are the main chemistries, used in applications from aircraft assemblies to wind turbine blade bonding.