Moisture from the environment or recent cleaning can affect footwear/flooring resistance measurements. ANSI/ESD STM97.1-2025 distinguishes controlled conditioning before installation from testing at ambient conditions on installed flooring.
Which conditioning requirements apply?
Pre-installation and installed-floor procedures
| Testing situation | STM97.1-2025 procedure | Required conditions |
|---|---|---|
| Evaluating a flooring system before installation | Section 6.1 | After cleaning, precondition the footwear and flooring samples for at least 72 hours at 12% ± 3% relative humidity and 23 °C ± 3 °C. Keep them in that environment until testing is complete. |
| Evaluating a new footwear type on a previously installed floor | Section 6.2 | Perform all tests at ambient temperature and humidity. |
| Evaluating a newly installed floor not previously evaluated under section 6.1, or an installed floor of unknown history or manufacturer | Section 6.3 | Perform all tests at ambient temperature and humidity. |
The requirements appear in sections 6.1.3.6, 6.2.2.6 and 6.3.2.6, with the controlled environment defined in section 5.6. The STM97.1 procedure-selection guide explains which procedure applies to each situation.
How can moisture affect resistance results?
Recent cleaning
Informative Annex B warns that water or moisture introduced by cleaning or the environment may produce misleading resistance values when testing occurs immediately after cleaning.
The requirement to test an installed floor at ambient conditions does not remove that concern. Sections 6.2 and 6.3 both refer to Annex B.
Hygroscopic materials
Some materials absorb moisture and can show widely varying resistance as relative humidity changes or cleaning introduces moisture. Annex B identifies leather as one example of a material whose results may fluctuate outside a specified resistance range as environmental conditions change.
For moisture-sensitive materials, Annex B advises discussing specifications under different humidity conditions and cleaning processes with the manufacturer.
Does 72 hours guarantee moisture equilibrium?
A minimum duration does not establish equilibrium for every material
No. Section 6.1 requires at least 72 hours of preconditioning, but informative Annex B notes that the surface of a hygroscopic material may take longer to equilibrate.
Annex B supplies no universal replacement duration. The section 6.1 minimum and the requirement to maintain the specified environment through testing remain applicable.
The pre-installation testing guide explains where conditioning fits within preparation, measurement and reporting.
Frequently Asked Questions
Yes. Informative Annex B of STM97.1-2025 warns that moisture introduced by cleaning or the environment can make readings taken immediately afterward misleading.
No. Sections 6.2 and 6.3 require ambient temperature and humidity, but both refer to Annex B’s guidance on moisture and cleaning. Ambient testing does not establish that moisture-sensitive materials have reached equilibrium.
No. It notes that some surfaces may need more than 72 hours to equilibrate but does not prescribe a universal longer duration. It is informative and does not replace section 6.1’s conditioning requirements.