Wet state anti-slip value testing service

Wet State Anti‑Slip Value Testing Service – Accredited ISO/IEC 17025 Slip Resistance and Safety Assessment for the Croatian Market

Wet state anti‑slip value is a critical safety parameter that quantifies the slip resistance of flooring surfaces, walkways, ramps, stair treads, and other pedestrian traffic areas when wet. This property is essential for preventing slip‑and‑fall accidents in commercial, industrial, residential, and public spaces, and is a key requirement for building safety certifications, occupational health and safety compliance, and product liability prevention. In the Croatian market, where the Hrvatski zavod za norme (HZN), the Ministarstvo gospodarstva i održivog razvoja, the Državni inspektorat, the Ministarstvo graditeljstva i prostornoga uređenja, and the Carinska uprava enforce strict quality, safety, and building standards aligned with EU directives and HRN EN (Croatian standards based on European norms), the accurate evaluation of wet state anti‑slip values is essential for product certification, building approval, supplier qualification, quality control in manufacturing, and import‑export processes. Our laboratory offers a comprehensive wet state anti‑slip value testing service, applying standardized methods such as EN 13036‑4, EN 13893, ASTM E303, ASTM F609, and HRN EN 13893 to measure the slip resistance of surfaces under controlled wet conditions. All tests are performed under our ISO/IEC 17025 (CNAS) accreditation, and the resulting reports are fully accepted by Croatian authorities and notified bodies, making them indispensable for regulatory compliance, product validation, and market access in Croatia and the European Union.

Surface and Material Samples We Regularly Test

Our laboratory receives a wide variety of surface materials and flooring products for wet state anti‑slip testing. Typical samples include:

• Floor tiles and ceramics – ceramic tiles, porcelain tiles, stone tiles, and quarry tiles for interior and exterior use.
• Resilient flooring – vinyl tiles, linoleum, rubber flooring, and cork flooring.
• Wood and wood‑based flooring – parquet, laminate, and engineered wood flooring.
• Concrete and cementitious surfaces – concrete pavements, screeds, and coatings.
• Metal surfaces – steel plates, gratings, and chequer plates for industrial and outdoor applications.
• Coated and painted surfaces – with anti‑slip coatings, paints, and surface textures.
• Stair treads and ramps – including safety stair treads with abrasive inserts.
• Prototype and new surface finishes – submitted by manufacturers for validation of slip resistance before series production.
• Field‑retrieved flooring samples – for failure analysis and condition assessment.

Pendulum Friction Testing (EN 13036‑4 / ASTM E303) – Standard Method for Measuring Slip Resistance

The pendulum friction test is the most widely used method for measuring the wet state anti‑slip value (coefficient of friction) of flooring surfaces. A pendulum‑type friction tester swings a rubber slider over the test surface, and the energy loss (converted to a friction value) is measured. Our procedures follow international standards and the requirements of the Croatian construction and safety sectors.

• Pendulum test – standard method (EN 13036‑4 / HRN EN 13036‑4 / NTC 5800 – for surface friction measurement) – we mount the pendulum tester on the test surface and condition the rubber slider (TRL or CEN slider) with water. The pendulum is released from a specified height, and the pointer indicates the friction value (the pendulum test value, PTV, or the British Pendulum Number, BPN). The test is performed with the slider wet and with the surface wet, at a specified temperature (typically 20 °C). We report the PTV or BPN value, the average of multiple measurements (at least 5), and the condition of the slider.
• Wet pendulum test with different contaminants (NTC 5801 – for simulating real‑world conditions) – we perform the pendulum test with the surface wetted with different liquids (e.g., water, soapy water, oil‑water mixtures, or a specific contaminant) to simulate the actual service conditions. We report the PTV for each contaminant.
• Pendulum test at different temperatures (NTC 5802 – for the temperature effect on slip resistance) – we perform the pendulum test at different surface temperatures (e.g., 5 °C, 20 °C, 40 °C) to evaluate the effect of temperature on the slip resistance. We report the PTV at each temperature.
• Pendulum test on textured and profiled surfaces (NTC 5803 – for the effect of the surface geometry) – for surfaces with a pronounced texture (e.g., grooves, studs, or embossing), we perform the pendulum test with the slider oriented in different directions (parallel and perpendicular to the texture) to evaluate the directional effect. We report the PTV for each orientation.
• Pendulum test on polished and worn surfaces (NTC 5804 – for the effect of wear) – we perform the pendulum test on new surfaces and on surfaces that have been artificially worn (by abrasion or by a specified number of cycles) to evaluate the durability of the slip resistance. We report the PTV for the new and the worn surfaces.

Horizontal Dynamic Coefficient of Friction Testing (ASTM F609 / EN 13893) – Standard Method for Walking Surfaces

The horizontal dynamic coefficient of friction (COF) test measures the slip resistance of a surface using a horizontally loaded sled, which is pulled across the test surface at a specified speed. This method is widely used for resilient flooring and for products that are tested in accordance with the European standard EN 13893.

• Horizontal dynamic COF test (ASTM F609 / EN 13893 / HRN EN 13893 / NTC 5810 – for flooring materials) – we mount the test sample on a horizontal platform and place a standard test sled (with a rubber or leather sole) on the sample. A specified vertical load (typically 500 N) is applied, and the sled is pulled horizontally at a constant speed (typically 0.5 m/s). The horizontal force required to maintain the motion is measured. The dynamic coefficient of friction (μ_d) is calculated as the ratio of the horizontal force to the vertical force. We report the μ_d value, the average of multiple measurements, and the test conditions.
• Wet dynamic COF test (NTC 5811 – for the wet condition) – we perform the dynamic COF test with the test sample wetted with water (or with a specified lubricant) to evaluate the slip resistance under wet conditions. The water is applied to the surface (or the sled) just before the test. We report the wet COF and the percentage of the dry COF that is retained.
• COF test at different speeds (NTC 5812 – for the speed effect on slip resistance) – we perform the dynamic COF test at different pulling speeds (e.g., 0.1 m/s, 0.5 m/s, 1.0 m/s) to evaluate the effect of the speed on the friction. We report the COF vs. speed curve.
• COF test with different sole materials (NTC 5813 – for the effect of the footwear) – we perform the dynamic COF test with different slider materials (e.g., standard rubber, leather, or a specific shoe sole material) to evaluate the effect of the footwear on the slip resistance. We report the COF for each slider type.
• COF test on curved and inclined surfaces (NTC 5814 – for the effect of the surface geometry) – we perform the dynamic COF test on curved or inclined surfaces (using a specially adapted fixture) to evaluate the slip resistance on ramps and curved walkways. We report the COF for the curved or inclined geometry.

Ramp and Inclined Surface Testing – Evaluating the Slip Resistance on Slopes

For ramps, stairways, and inclined surfaces, the slip resistance is often evaluated by measuring the angle at which a person begins to slip. Our ramp tests simulate these conditions and provide a direct measure of the slip resistance on slopes, which is essential for the design of accessible and safe public spaces in Croatia.

• Ramp slip test (NTC 5820 – for the critical angle of slip) – we mount the test surface on a ramp that can be inclined at a controlled angle. A test person (or a standard test sled) walks on the ramp with the surface wetted, and the angle at which slipping occurs is measured. We report the critical angle (in degrees) and the corresponding coefficient of friction.
• Inclined surface friction test (NTC 5821 – for the static friction measurement) – we place a test block (with a rubber base) on the inclined surface and gradually increase the inclination angle until the block begins to slide. The static coefficient of friction is calculated from the angle of inclination. We report the static coefficient of friction and the angle of inclination.
• Ramp test with different contaminant conditions (NTC 5822 – for the effect of contaminants) – we perform the ramp test with water, soapy water, oil, or other contaminants on the surface. The critical angle is measured for each contaminant. We report the critical angle and the contaminant effect.
• Ramp test with different footwear (NTC 5823 – for the effect of the shoe type) – we perform the ramp test with different types of footwear (e.g., work boots, sports shoes, and dress shoes) to evaluate the effect of the shoe sole on the slip resistance. We report the critical angle for each footwear type.
• Ramp test at different temperatures (NTC 5824 – for the effect of the temperature) – we perform the ramp test at different surface temperatures (e.g., 5 °C, 20 °C, 40 °C) to evaluate the effect of the temperature on the slip resistance. We report the critical angle at each temperature.

Surface Roughness and Texture Analysis – Correlation with Slip Resistance

The slip resistance of a surface is strongly influenced by its roughness and texture. Our surface roughness and texture analysis tests provide a fundamental characterization of the surface, which can be correlated with the measured slip resistance. This helps to understand the mechanism of slip resistance and to optimize the surface design.

• Surface roughness measurement (ASTM D7127 / NTC 5830 – for the roughness parameters) – we measure the surface roughness (Ra, Rz, and Rmax) of the test surface using a contact profilometer or an optical profiler. The roughness parameters are correlated with the slip resistance. We report the roughness parameters and the correlation.
• Surface texture analysis (NTC 5831 – for the 2‑D and 3‑D topography) – we perform a 2‑D and 3‑D surface texture analysis (using an optical profilometer) to determine the surface topography, the peak density, and the mean slope of the surface asperities. The texture parameters are correlated with the slip resistance. We report the texture maps and the correlation.
• Water film thickness and drainage analysis (NTC 5832 – for the effect of water on the slip resistance) – we measure the thickness of the water film on the surface (using a thin‑film sensor) and evaluate the drainage characteristics of the surface texture. The water film thickness is correlated with the slip resistance. We report the water film thickness and the drainage efficiency.
• Surface porosity and micro‑texture (NTC 5833 – for the effect of the surface micro‑structure) – we use scanning electron microscopy (SEM) to examine the micro‑texture and the porosity of the surface. The micro‑texture is correlated with the slip resistance and the ability to maintain the slip resistance under wear. We report the SEM images and the correlation.
• Wear and aging effect on the surface roughness (NTC 5834 – for the durability of the slip resistance) – we measure the surface roughness before and after a specified number of wear cycles (e.g., 10,000 cycles using a Taber abraser) to evaluate the durability of the slip resistance. We report the change in the roughness and the effect on the slip resistance.

Environmental and Aging Effects on Wet Anti‑Slip Performance – Evaluating Durability

The wet state anti‑slip value can change over time due to aging, wear, and exposure to environmental factors. Our environmental and aging tests evaluate the long‑term stability of the slip resistance, which is essential for ensuring the safety of the flooring over its service life in the diverse Croatian climate (coastal, continental, and mountainous).

• UV and weathering effect (ASTM G154 / NTC 5840 – for the outdoor exposure) – we expose the test surface to UV radiation (UVA‑340) and condensation cycles for a specified duration (e.g., 500 hours). We then re‑measure the wet anti‑slip value. We report the change in the anti‑slip value and the visual condition.
• Thermal aging and humidity effect (NTC 5841 – for the high‑temperature and humidity exposure) – we expose the test surface to a high‑temperature (e.g., 60 °C) and high‑humidity (e.g., 90 % RH) environment for a specified duration (e.g., 7 days). We then re‑measure the wet anti‑slip value. We report the change in the anti‑slip value and the effect on the surface.
• Chemical and cleaning agent exposure (NTC 5842 – for the effect of cleaning on the slip resistance) – we expose the test surface to common cleaning agents (e.g., alkaline cleaners, acidic cleaners, or disinfectants) and then re‑measure the wet anti‑slip value. We report the change in the anti‑slip value and the compatibility with the cleaning agents.
• Abrasion and wear effect (NTC 5843 – for the effect of foot traffic on the slip resistance) – we subject the test surface to a specified number of abrasion cycles (e.g., using a floor abrasion tester or a Taber abraser) and then re‑measure the wet anti‑slip value. We report the change in the anti‑slip value and the wear condition.
• Freeze‑thaw effect (NTC 5844 – for the outdoor surfaces in cold climates) – we subject the test surface to cycles of freezing (e.g., -20 °C) and thawing (e.g., 20 °C) and then re‑measure the wet anti‑slip value. We report the change in the anti‑slip value and the freeze‑thaw resistance.

Compliance with Safety Standards and Classification – Pass/Fail Criteria

The measured wet state anti‑slip value is compared with the requirements of the relevant safety standards and building codes to determine the classification and the suitability of the flooring for its intended use. Our tests provide a clear pass/fail result and a classification (e.g., R‑class for ramps, B‑class for walkways).

• Classification according to EN 13893 (NTC 5850 – for resilient flooring) – we classify the flooring material according to the EN 13893 standard (Classes A, B, C, or D) based on the measured wet COF. The classification indicates the slip resistance (A = high resistance, D = low resistance). We report the class and the corresponding COF range.
• Classification according to DIN 51130 (NTC 5851 – for ramps and inclined surfaces) – we classify the flooring material according to the DIN 51130 standard (R‑classes: R9, R10, R11, R12, R13) based on the pendulum test value (PTV) or the ramp test result. The R‑class indicates the resistance to slipping on an inclined surface (R9 = lowest resistance, R13 = highest resistance). We report the R‑class and the test result.
• Compliance with the Croatian building regulations (NTC 5852 – for the building safety) – we compare the measured wet anti‑slip value with the minimum requirements of the Croatian building regulations (based on the HRN EN standards) for different types of pedestrian areas (e.g., for public buildings, stairways, and ramps). We report the compliance and the pass/fail status.
• Guarantee verification (NTC 5853 – for the contractual purposes) – we test the flooring material to verify that the wet anti‑slip value is within the guaranteed value specified in the purchase order or the design specification. We report the measured value and the margin relative to the guarantee.
• Comparative testing for material selection (NTC 5854 – for the product comparison) – we perform comparative tests on multiple floor coverings (or different surface treatments) to select the material with the best slip resistance for the intended application. We report the comparative results and the recommendation.

Complementary Tests – Visual Inspection, Gloss, and Color for Surface Quality Assessment

To provide a comprehensive assessment of the flooring quality and to correlate the slip resistance with the surface appearance, we perform complementary tests, including visual inspection, gloss measurement, and color measurement.

• Visual inspection for surface defects (NTC 5860 – for the detection of cracks, stains, and other defects) – we inspect the test surface for any visible defects (cracks, chips, stains, or unevenness) that could affect the slip resistance. We report the visual condition and any defects.
• Gloss measurement (ASTM D523 / NTC 5861 – for the gloss level of the surface) – we measure the gloss (in GU) of the test surface at a specified angle (e.g., 60°). The gloss is correlated with the slip resistance (a high‑gloss surface is generally more slippery). We report the gloss value and the correlation with the slip resistance.
• Color measurement (ASTM D2244 / NTC 5862 – for the surface color and the uniformity) – we measure the color (L*, a*, b*) of the test surface using a spectrophotometer, to verify the color uniformity and to detect any discoloration. We report the color values and the ΔE*.
• Water absorption and porosity (ASTM C642 / NTC 5863 – for the surface porosity) – we measure the water absorption (in %) and the porosity (in %) of the test surface, which can affect the slip resistance and the durability. We report the water absorption and the porosity.
• Surface hardness (ASTM D2240 / NTC 5864 – for resilient flooring) – we measure the Shore A or Shore D hardness of the surface (for resilient flooring and coatings), which can affect the slip resistance and the wear resistance. We report the hardness and the correlation with the slip resistance.

Test Report and Recognition in the Croatian Construction, Safety, and Building Sector

All procedures described are within the scope of our ISO/IEC 17025 accreditation, with equipment calibrated periodically (pendulum testers, slip resistance testers, profilometers, etc.) and traceability to international standards (NIST, PTB). Our test reports are issued in English (with a Croatian summary available on request) and include:

• Full identification of the sample (flooring type, manufacturer, product name, lot number, and surface finish).
• Detailed description of the test methods applied (ASTM/ISO/EN/HRN EN/NTC standards, test conditions, and measurement parameters).
• Numerical results: pendulum test value (PTV or BPN), dynamic coefficient of friction (μ_d), critical angle (°), R‑class, EN 13893 class, surface roughness (Ra, μm), and gloss (GU).
• Graphical data: friction vs. time curves, roughness profiles, and surface texture maps.
• Comparative tables against the values specified by the client or against the limits of the relevant standards (EN 13036‑4, EN 13893, ASTM E303, DIN 51130, HRN EN 13893, and the requirements of the HZN, Ministarstvo graditeljstva, and Državni inspektorat).
• Classification of the flooring material according to the safety standards (R‑class, EN 13893 class).
• Photographs of the test surface and the test setup.
• Recommendations for material selection, surface treatment, and maintenance to achieve the required slip resistance and safety.
• Expanded uncertainty (k=2) for all key measurements, calculated according to the ISO/IEC 98‑3 Guide.

These reports are fully accepted by the Hrvatski zavod za norme (HZN) for the verification of product conformity, by the Ministarstvo graditeljstva i prostornoga uređenja for building approval and safety compliance, by the Državni inspektorat for market surveillance, and by the Carinska uprava (Croatian Customs) for tariff classification and quality verification in the import of flooring materials. Additionally, we offer consulting services for the selection of anti‑slip floor coverings, the design of safety‑compliant walkways, and the implementation of slip resistance monitoring programs, contributing to the safety, accessibility, and quality of public and private spaces in the diverse and growing Croatian market, from the coastal tourist facilities to the commercial and industrial buildings of the continental regions.