Flooring that gets high foot traffic and can get wet or greasy in use needs slip resistance (or skid resistance) that stands up well under wear rather than losing its wet slip resistance after a few weeks. McDonalds Restaurants spent years in research and devised a laboratory slip test that assesses how well the wet slip resistance persists under simulated foot traffic. Flooring with slip resistance that successfully survives 500 cycles of abrasion with a standard 3-inch square abrasive pad loaded with one kilogram is said to have Sustainable Slip Resistance (SSR).
Lots of ceramic tiles are known to have SSR. Barbara Cohen, along with her team from Miller Druck Specialty Contracting (New York), and Miller Druck International Stone (London & Italy), wanted to offer her clients natural stone with SSR. (Her company is a trend‐setter in stone for high‐end properties and large-scale public works.) We slip tested 35 selected proprietary samples, using a soft TRL rubber slider to simulate shoe bottoms, and found that 26 of the samples qualified as having SSR. With Ms. Cohen’s permission we show the results in the table below, with the samples that have Sustainable Slip Resistance shown in blue. Click on the table to see it at legible size.
“Wet PTV” indicates wet Pendulum Test Value. McDonalds’ specification for their customer areas requires a wet PTV of at least 35 after abrasion to qualify a sample as having SSR.
Table 1. Miller Druck SSR data from Safety Direct America
At the bottom of the table are “batting averages” showing which finishing techniques yielded SSR. Miller Druck’s flamed finish did in 19 of 20 samples, for a batting average of .950. Three sand-sprayed samples all had SSR. Miller Druck along with Sotter Engineering’s Safety Direct America will prepare and skid test samples for your project to achieve SSR for the desired appearance and functionality.
The table shows PTV after abrasion ranging from the minimum of 35 (for the samples that have SSR) to a maximum of 63. Situation-specific safety standards indicate that the latter is suitable, for instance, for external ramps with slopes greater than 1 in 14, and for swimming pool ramps and stairs leading to water. These are the most demanding slippery situations that are defined at present by the standards. For many wet areas, including private bathrooms, public restrooms, and undercover concourse areas of stadiums, a wet PTV of 35 is adequate.
Miller Druck’s unpublished catalog of natural stone with Sustainable Slip Resistance is the world’s largest. The products are available worldwide through Miller Druck’s several offices.