Slider 55 and 57 for Pool Pendulum Testing

The slider problem in plain terms

Imagine a polished tile pool surround. Tested with Slider 96 (a Four-S rubber heel compound, hard) you might get a wet PTV of 32 — moderate slip potential. Tested with Slider 55 (a softer compound simulating bare wet skin) you might get a wet PTV of 18 — high slip potential. Same surround, same water, same pendulum — different sliders give different results because they're answering different questions about a different user.

For a pool, the user is barefoot, so the relevant question is the bare-skin one. Slider 55 is the correct slider. A pool report based on Slider 96 alone is a report about a hypothetical shod user who doesn't actually exist on the pool surround.

Slider 55 — wet barefoot environments

Slider 55 is a softer rubber compound (55 IRHD on the International Rubber Hardness Degrees scale) that simulates the friction of bare wet skin on a wet floor. It is the principal slider for:

• Pool surrounds (the main flat tile surface around the pool)
• Pool steps and ladder approach zones
• Hydrotherapy pool surrounds and ramps
• Wet shower cubicles
• Communal shower floors
• Wet changing room main floors where users are barefoot
• Spa pool and Jacuzzi surrounds
• Outdoor lido and natural swimming wet zones

Slider 57 — sock and soft-sole environments

Slider 57 simulates a soft-sole footwear contact (slipper, swim shoe, sock). It is appropriate for:

• Changing room transition zones where users may be in socks or pool shoes
• Hydrotherapy approach zones where patients are often in soft pool shoes for safety
• Care-home pool changing rooms where residents are often in slippers
• Some learner-pool environments where children are in pool shoes

Where both barefoot and soft-sole users are foreseeable in the same zone, both Slider 55 and Slider 57 should be used and reported separately.

Slider 96 — limited pool role

Slider 96 (the standard shod environment slider) has limited pool relevance. It is used at:

• Pool reception and dry approach zones
• Lifeguard chair access and circulation routes
• Plant room and back-of-house areas
• External pool deck zones used in shoes (some hotel rooftop pools)

Why mis-selection invalidates a pool test

A pool surround tested with Slider 96 will produce PTV results that may meet the 36+ threshold — and an inexperienced reviewer might conclude the surface is compliant. But the surface as tested is not the surface as walked on. The barefoot pool user on the same surround experiences materially different friction, and the test result is therefore not evidence about that user's actual slip risk.

For litigation, this is a fatal weakness. A defendant whose periodic testing programme used Slider 96 throughout a pool environment will see their evidence dismissed by the claimant's expert with a single line: 'The wrong slider was used.' Periodic data with the right slider, by contrast, is unimpeachable on this point.

Mixed environments — the changing room boundary

The changing room/pool surround boundary is the most common mixed environment. Users transition shoe → bare foot → wet bare foot. Best practice is to test the changing-room main floor with Slider 57 (soft sole) and Slider 96 (any shod entry), then test the surround threshold and beyond with Slider 55 (wet barefoot). Reports for these zones quote multiple PTVs at the same point, one per slider, so the reviewer sees the full friction picture for each likely user mode.

Slider conditioning

Whichever slider is fitted, the slider edge must be conditioned to standard roughness before each set of recorded swings — typically by abrading on prescribed lapping paper. Insufficient or incorrect conditioning produces unreliable results regardless of slider selection. The conditioning protocol is part of the BS EN 16165 Annex C method and is one of the items UKAS assessors verify during accreditation surveillance.