Abstract: A contacting mechanical end face seal for use in applications having slow shaft rotational speeds, such as mixers, agitators and reactors, includes at least one seal ring having a face with spiral grooves. Both hydrostatic and hydrodynamic lift characteristics in the seal are utilized to generate and maintain a seal gap having sufficient stiffness to prevent contact of the seal ring faces during operation. Specific characteristics, or combinations of them, include a land to groove ratio between 0.2-0.9, tapered groove surfaces which are inclined from the O.D. toward the dam, groove area to land area ratios greater than 1.5, a stepped groove having a greater depth at the O.D. relative to the depth adjacent the dam, alternating deep and shallow grooves, and groove area to dam area ratio in the interface greater than 1.2.