Slip Resistance Characteristics of Footwear Solings Assessed Using the SATRA Friction Tester

Abstract The development of the SATRA Friction Tester was described in ASTM STP 1103-1990. Since then the tester has been used in regular service and research work, testing and evaluating a wide range of footwear types and soling materials. This paper reviews some of the experience gained and presents data on the ranges of friction values associated with different types of commercially used soling materials. The data presented correlate well with industry experience, validating the test method. The findings of some additional complementary research is also reported including results of studies on the relationship between soling material hardness and measured friction. For example, on a dry surface, smooth PVC soling friction decreases with increasing hardness and wet friction increases up to a certain hardness level. A tread pattern, however, reverses the hardness effect on the wet surface, giving results comparable with smooth PVC in the dry. Other results show the significant effects of abrasion of solings and floor surfaces on slip resistance and the key contribution of surface roughness to wet friction. Finally, some of the problems surrounding standards development and the setting of pass levels are discussed. A number of areas for future research are identified and it is suggested that future studies look at the shoe, floor, and surface contamination as interactive components of a single system in which solings and floorings need to have complementary properties to optimize slip resistance.