How tight are the bond line tolerances for assuring effective adhesive bonding?

Gap filling, solventless adhesive systems such as epoxies, polyurethanes and silicone materials are very tolerant of variations in bond line thickness. Master Bond formulations based on these and other polymer systems can produce high performance bonds with assemblies whose bonding surfaces have tolerances up to 20 mils and even more. Highest strengths are usually achieved when adhesive bonds range from 2-5 mils in thickness.