As a general rule, the lower the sealing surface finish, the better the overall seal performance that can be expected. Lower finish value reduces wear and increases seal life. A 40 Rockwell C hardness or greater is recommended for slow to moderate reciprocating motion.

　　The ideal hardness is 55 to 65 Rockwell C. Hardness in this range is recommended for moderate- to high-speed linear or rotary motion. Hard anodized surface finishes must be polished after anodizing.

　　Testing has shown that grinding of the shaft is the best method of machining, providing lower friction and heat generation than polishing the surface with a polishing cloth. Spiral grinding marks may cause helical pumping, leading to leakage; therefore, plunge grinding is recommended. When plunge grinding, make sure to avoid even ratios between shaft and wheel speed.