Slip ratings aren’t fixed—they reflect the condition of the actual surface tested.

A surface that achieves a P4 rating in its raw form may perform very differently once it’s sealed, polished, or coated. And that difference can shift your product from compliant to non-compliant without anyone noticing—until it’s too late.

Why P-Ratings Change

The wet pendulum test under AS 4586-2013 measures how much grip a surface offers when wet. That grip is heavily influenced by:

• Micro-texture and surface profile
• Coatings, sealers, or polishes applied after manufacture
• Changes to gloss, absorption, or roughness

Even invisible treatments—like a clear anti-slip coating or matte sealer—can alter test results by one or more full classifications.

When Coatings Reduce Slip Resistance

We’ve seen products shift from P4 to P2 after sealing—particularly when the coating increases gloss or reduces surface roughness. That shift could take a compliant bathroom or entry tile and render it unsuitable for wet areas under HB198-2014 guidelines.

When Coatings Improve Performance

Some anti-slip treatments are designed to increase micro-friction. These may improve the P-rating—but only if the treated surface is tested and certified. Applying a coating and assuming it works is not defensible.

Key Compliance Requirement

Under AS 4586:2013, you should test the final, treated surface as supplied or installed.

If you modify the surface after manufacture—whether by coating, sealing, or finishing—you are obligated to:

• Retest the product
• Update the slip classification
• Ensure marketing and certification reflect the treated condition

Failure to do this can invalidate the slip rating and create liability under product compliance laws.

Best Practice for Suppliers and Builders

• Test both coated and uncoated versions if finishes vary
• Label all test results clearly (“as sealed”, “as installed”, etc.)
• Submit the actual installation configuration for certification
• Don’t assume ratings are transferable between finishes

Zerofal provides lab testing under AS 4586-2013 for all finish conditions—sealed, coated, untreated, or otherwise. We help manufacturers and specifiers certify what actually gets installed.