Historically, slip testing floors was done by a person walking across the floor with a weighted shoe and then dragging the heel of the shoe to measure how much friction was created. The resulting Coefficient of Friction (CoF) was then used to classify the floor’s slip resistance in either dry or wet conditions. This was not a particularly reliable method of slip testing floors, and tended to produce results that were skewed by many factors.
More recently, it was common to see experts use a specialized tribometer called the James Machine to perform the same test. This device measures the static CoF of polished and waxed floors – it is not designed for measuring the slip potential of actual floors. Unfortunately this device is widely promoted by flooring manufacturers, floor polishing associations and “tile institutes” in the USA. This is because these entities have a financial interest in selling slippery flooring to unsuspecting Americans. Using the James Machine to perform wet floor slip tests can give a false passing grade to virtually any surface, even ones that are dangerously slippery when they are wet.
In the UK, the HSE prefers to use a wet pendulum test that simulates how the heel of a pedestrian makes contact with a surface and produces a valid result for assessing a floor’s slip potential in both dry and wet conditions. In fact, a wet pendulum test is the only test that provides a true indication of how a floor will behave under realistic real-world conditions.
This is why it is important to seek a valid slip resistance test for floors, particularly those that are likely to be contaminated and wet in use. Pendulum tests can be performed in Stonhard’s laboratory or on site around the world with our specialist regularly-calibrated machines.
In general, for a low slip potential to be achieved, the floor must have sufficient micro-roughness to make solid contact with a pedestrian’s heel and break through any contaminant that might be present on the shoe sole. The tribometers that Stonhard uses, including the BOT-3000E and the English XL VIT, provide data which is comparable to the pendulum test, but are more accurate for measuring wet surfaces.
Having valid slip resistance results in both wet and dry conditions is essential because most floors are slippery when they are wet. It is also necessary to understand how a floor’s slip resistance can vary based on the environment and cleaning regime, in order to design safe floors that will last under normal use. This is why we encourage all of our customers to consider a wet PTV slip resistance test as part of their floor specification process. The PTV test gives a more realistic indication of the safety performance of any given floor surface and is supported by 50 years of internationally-accepted slip resistance research. Unlike wet ramp tests, PTV’s are a good indicator of sustained slip resistance and can be monitored over time to assess the effectiveness of a cleaning regime.