The ASTM C 1028-07 has several weaknesses that make it an unreliable safety test for measuring floor friction. Here are just a few:
- Stiction: when testing wet surfaces that are polished (or very flat or glossy), the test rubber used in the C 1028 test will stick (or suction itself) to the test surface and provide safe readings to floors that are very unsafe when wet. In other words, the C1028 test on very flat surfaces measures the amount of suction the surface provides to a large piece of rubber, which has absolutely nothing to do with human traction.
- The C 1028 test method calls for the tester to pull on a test slider loaded with a 50-pound weight. Each individual tester, of course, will pull on the test assembly differently, leading to different results for each individual tester. Each individual tester will also obtain different results at different times and on different days based on whether the tester is tired, just drank coffee, is on medication, hung over, angry, wants the floor to pass or not pass, etc.
- The C 1028 measures "Static Coefficient of Friction" (SCOF), which gives a measurement of how slippery a floor is when someone is standing still on it. Slips, of course, usually happen when people are in motion over the floor surface. So the ASTM C 1028-07 isn't measuring anything that will tell us if people will slip or not while in motion over the floor, making turns on the floor, or hurrying to get to an elevator or train on the floor. It simply tells us if someone will slip while standing still on the floor.
- Table 2 of the ASTM C 1028-07 method states that the reproducibility limit of the test is up to 0.1023. This means that if one lab gets a result of 0.50 for Static Coefficient of Friction and another lab gets 0.60, then either reading is considered equally valid. So if you buy a tile that is rated as having a SCOF using C 1028 of 0.60, it could have been tested at 0.50 by one laboratory as well as 0.60 by another lab. Is it really 0.60 and "safe?" You'll never know until someone slips on your floor. For more detail on the precision of this method, click here.
- The ASTM committee that formulated the C 1028 test documented many times in their meeting minutes that it is not intended to assess slip safety. For highlighted excerpts from the minutes of that meeting, including a record of the near-unanimous voting on relevant issues, click here.
ASTM C1028-07 SCOF test in progress on a floor
ASTM C1028-07 has officially been withdrawn, with no replacement
, in 2014. There are no plans to resurrect this poor wet static of coefficient test method in the future.