Sample Preparation for Pendulum Testing

In-service testing — minimal preparation

For routine periodic and post-incident testing, the principle is to test the surface in the condition the public actually walks on. Heavy preparation that produces a 'clean' result not representative of the surface in normal use is misleading.

Standard practice is to:

• Sweep the test area to remove loose dust, grit and debris that would interfere with the slider
• Note the cleaning state of the surface (post-deep-clean, mid-cycle, end-of-day)
• Photograph the surface as found, before any disturbance
• Test wet using clean tap water at ambient temperature
• For surfaces with operational contamination (oil, soap), test under that contamination only where this is the specifically asked question

Slider conditioning before each test set

The rubber slider edge is conditioned to standard roughness before each set of recorded swings. This is part of the test method, not part of surface preparation, but it interacts:

• The slider is abraded on prescribed lapping paper for a specified number of strokes
• Without conditioning, the slider becomes glassy and PTV readings drift downward over the test session
• Over-conditioning (too many strokes or too coarse paper) makes the slider edge inconsistent

Documenting the conditioning protocol is part of the UKAS-accredited record.

Laboratory sample preparation

For laboratory or factory testing on flooring samples (research, manufacturer datasheet generation, dispute investigation of retained samples), preparation is more controlled:

• Sample is cleaned to a defined protocol and dried
• Sample is conditioned at the laboratory's ambient temperature and humidity for a defined period
• Sample is fixed to the test rig in the same orientation expected in service
• Test contaminant (water, oil, soap solution) is applied per the relevant method

The point is reproducibility — different laboratories testing the same product should produce the same result.

Forensic sample preparation

For forensic work — testing a retained sample or section of original flooring as part of slip-claim investigation — preparation is documented in detail because it directly affects the evidential value:

• The sample's chain of custody from removal through testing
• The state of the sample as received vs the state at the time of the incident
• Any cleaning or conditioning done before testing, and why
• Comparison with photographs of the sample's appearance at the time of the incident

The aim is to produce test data that can be confidently traced back to the incident-time surface — or, where the chain has been broken, to identify exactly where and how.

What not to do

• Don't deep-clean the surface immediately before testing if the test is supposed to capture in-service conditions
• Don't apply a polish or treatment before testing unless this is the specific question being asked
• Don't test wet with anything other than clean tap water unless the report specifies the contaminant
• Don't test a surface that has been recently mopped without allowing the standing water to be displaced or applied as a clean wet film
• Don't test through standing puddles — the slider must contact the surface, not a fluid film thicker than the texture