Screen grease resistance testing service

Screen Grease Resistance Testing Service – Accredited ISO/IEC 17025 Surface Contamination and Cleanability Assessment for the Croatian Market

Screen grease resistance is a critical performance parameter that quantifies the ability of display surfaces, touch panels, protective films, and coated glass to resist the adhesion, spreading, and visibility of oily contaminants such as fingerprints, skin oils, cosmetics, and food residues. This property is essential for ensuring the optical clarity, touch sensitivity, user comfort, and hygiene of screens used in smartphones, tablets, laptops, automotive displays, medical monitors, industrial control panels, and public kiosks. In the Croatian market, where the Hrvatski zavod za norme (HZN), the Ministarstvo gospodarstva i održivog razvoja, the Državni inspektorat, the Agencija za zaštitu okoliša (AZO), and the Carinska uprava enforce strict quality, safety, and consumer protection standards aligned with EU directives and HRN EN (Croatian standards based on European norms), the accurate evaluation of screen grease resistance is essential for product certification, supplier qualification, type testing, quality control in manufacturing, and import-export processes. Our laboratory offers a comprehensive screen grease resistance testing service, applying standardized methods such as ASTM D5946, ASTM F1854, ISO 25178, IEC 62326-1, and HRN EN ISO 25178 to measure contact angle, surface energy, fingerprint visibility, and cleanability under controlled conditions of temperature, humidity, and simulated use. 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.

Screen and Display Samples We Regularly Test

Our laboratory receives a wide variety of screen and display products for grease resistance testing. Typical samples include:

• Smartphone and tablet screens – glass and polymer displays with anti-fingerprint, oleophobic, and anti-glare coatings.
• Laptop and monitor displays – for commercial, consumer, and professional applications.
• Automotive and navigation displays – touchscreens and instrument clusters for vehicles.
• Medical and healthcare monitors – for diagnostic, surgical, and patient monitoring systems.
• Industrial control panels and kiosks – for public and industrial environments.
• Protective films and screen protectors – aftermarket and OEM products for surface protection.
• Prototype and new screen coatings – submitted by manufacturers for validation of grease resistance before series production.
• Field-retrieved screens – for failure analysis and remaining life assessment.

Contact Angle and Surface Energy Measurement – Quantifying Grease Resistance

The contact angle of a liquid droplet (typically water, diiodomethane, or a synthetic oil) on the screen surface is a direct measure of the surface's ability to repel oils and greases. A high contact angle (> 90°) indicates a hydrophobic/oleophobic surface, while a low contact angle indicates a hydrophilic/oleophilic surface. Our tests follow international standards and the requirements of the Croatian electronics, automotive, and medical device sectors.

• Static contact angle measurement (ASTM D5946 / ISO 15989 / HRN EN ISO 15989 / NTC 5600 – for surface wettability) – we place a small droplet of a specified liquid (typically deionized water or diiodomethane) on the screen surface using a precision dispenser. The contact angle is measured using a goniometer with a high-resolution camera and image analysis software. We report the static contact angle (in degrees), the surface energy (in mN/m), and the polar and dispersive components of the surface energy. A high water contact angle (> 100°) indicates a good grease repellency.
• Dynamic contact angle measurement (NTC 5601 – for advancing and receding angles) – we measure the advancing and receding contact angles (the angles during droplet expansion and contraction) to evaluate the surface heterogeneity and the hysteresis. We report the advancing angle, the receding angle, and the hysteresis.
• Contact angle measurement with synthetic sebum (NTC 5602 – for the simulated skin oil) – we use a synthetic sebum (a mixture of fatty acids, triglycerides, and squalene) as the test liquid to simulate the actual skin oils. The contact angle and the spreading area of the sebum droplet are measured. We report the contact angle of the sebum and the spreading area (in mm²).
• Contact angle measurement at different temperatures (NTC 5603 – for the thermal effect) – we perform the contact angle measurement at elevated temperatures (e.g., 40 °C, 60 °C) to evaluate the effect of temperature on the surface repellency. We report the contact angle at each temperature.
• Contact angle measurement after aging (NTC 5604 – for the durability assessment) – we age the screen surface (e.g., by UV exposure, thermal aging, or abrasion) and then re‑measure the contact angle. The change in the contact angle is a measure of the durability of the grease‑resistant coating. We report the contact angle after aging and the retention of the repellency.

Fingerprint and Smudge Visibility Testing – Evaluating the Optical Clarity

The visibility of fingerprints and smudges on the screen is a direct measure of the grease resistance performance. Our tests simulate the deposition of fingerprints and evaluate the optical clarity and the cleanability of the surface. These tests are essential for the quality control of screen protectors and anti‑fingerprint coatings.

• Fingerprint deposition and visibility test (ASTM F1854 / NTC 5610 – for the fingerprint evaluation) – we apply a standardized artificial fingerprint (or a real human fingerprint with a specified pressure) to the screen surface. The fingerprint is then inspected visually under controlled lighting conditions. The visibility is rated on a scale from 0 (invisible) to 5 (highly visible). We report the visibility rating and the area of the fingerprint.
• Smudge and streak test (NTC 5611 – for the cleaning and smudge resistance) – we apply a controlled amount of a greasy contaminant (e.g., a mixture of oils or a commercial fingerprint simulator) to the screen surface and then wipe the surface with a standard cleaning cloth. The remaining smudge and streaks are evaluated visually and by measuring the haze (in %). We report the smudge visibility and the haze change.
• Artificial fingerprint test with different pressures (NTC 5612 – for the pressure effect) – we apply the artificial fingerprint with different pressures (e.g., 1 N, 5 N, 10 N) to simulate the varying contact pressures during normal use. The visibility of the fingerprint at each pressure is reported. We report the visibility rating for each pressure.
• Fingerprint visibility at different viewing angles (NTC 5613 – for the angle effect) – we inspect the fingerprint at different viewing angles (e.g., 0°, 30°, 45°, 60°) and under different lighting conditions. The visibility is evaluated. We report the visibility at each angle and the ambient light condition.
• Fingerprint cleanability test (NTC 5614 – for the ease of cleaning) – we apply a fingerprint (or a smudge) to the screen and then clean the surface with a standard cleaning cloth (or a cleaning solution) using a specified number of wiping cycles. The number of cycles required to completely remove the fingerprint is recorded. We report the number of cleaning cycles and the cleanability rating.

Surface Roughness and Topography – Evaluating the Physical Structure of the Coating

The surface roughness and topography of the screen coating significantly influence the grease resistance. A smoother surface provides fewer sites for the adhesion of oils, while a textured surface can trap oils and make them more visible. Our tests measure the surface roughness and the topography using non‑contact optical methods, providing a quantitative assessment of the surface quality.

• Surface roughness measurement (ISO 25178 / NTC 5620 – for the 3‑D surface parameters) – we use a white light interferometer (or a confocal microscope) to measure the surface roughness (Sa, Sq, Sz, Ssk, and Sku) of the screen coating. The roughness parameters are correlated with the grease resistance and the finger‑print visibility. We report the 3‑D roughness parameters and the surface map.
• Surface texture and peak density (NTC 5621 – for the lateral structure) – we measure the peak density (Spd) and the mean peak‑to‑peak distance (Spc) from the 3‑D surface map. A high peak density can reduce the contact area and improve the grease repellency. We report the Spd and the Spc.
• Surface energy distribution (NTC 5622 – for the local surface heterogeneity) – we perform a micro‑contact angle measurement (using a micro‑goniometer) at multiple points on the surface to map the local surface energy distribution. The heterogeneity is correlated with the finger‑print visibility and the cleanability. We report the surface energy map and the heterogeneity index.
• Coating thickness and uniformity (NTC 5623 – for the layer integrity) – we measure the thickness of the anti‑fingerprint coating (in nm) using an ellipsometer or a spectrophotometer. The uniformity of the coating is evaluated. We report the coating thickness and the uniformity.
• Surface defect analysis (NTC 5624 – for the detection of defects) – we inspect the screen surface for any defects (e.g., scratches, pinholes, or coating defects) that could affect the grease resistance and the finger‑print visibility. We report the defect type, the size, and the location.

Abrasion and Durability Testing – Evaluating the Long‑Term Grease Resistance

The grease resistance of a screen coating can diminish over time due to mechanical abrasion, cleaning, and wear. Our abrasion and durability tests simulate the repeated contact and cleaning cycles, and they evaluate the retention of the grease‑resistant properties. These tests are essential for the certification of long‑life screen products in the Croatian market.

• Abrasion test (ASTM F1854 / NTC 5630 – for the mechanical wear of the coating) – we subject the screen surface to a specified number of abrasion cycles (e.g., 1,000 cycles, 5,000 cycles) using a Taber abraser (with a specified abrasive wheel) or a linear abrasion tester with a steel wool pad or a felt pad. After the abrasion, we re‑measure the contact angle and the finger‑print visibility. We report the contact angle after abrasion and the retention of the grease resistance (in %).
• Cleaning durability test (NTC 5631 – for the cleaning agent resistance) – we apply a specified cleaning agent (e.g., isopropyl alcohol, a commercial screen cleaner, or a mild detergent) to the screen surface and wipe it with a cloth for a specified number of cycles. We then re‑measure the contact angle. We report the contact angle after the cleaning cycles and the retention of the repellency.
• Environmental durability test (NTC 5632 – for the combined stress) – we expose the screen surface to a combination of environmental stresses (e.g., UV radiation, high temperature, and high humidity) and then perform the abrasion test and the finger‑print visibility test. The combined effect of the environmental stress and the mechanical wear is reported. We report the retention of the grease resistance after the combined stress.
• Fingerprint resilience test (NTC 5633 – for the repeated fingerprint deposition and cleaning) – we apply a fingerprint to the screen, clean it, and repeat the process for a specified number of cycles (e.g., 100, 500, or 1000 cycles). We evaluate the finger‑print visibility and the contact angle after each set of cycles. We report the durability of the grease resistance.
• Chemical resistance test (NTC 5634 – for the chemical attack) – we expose the screen surface to various chemicals (e.g., sunscreen, hand lotion, or a cosmetic product) for a specified duration (e.g., 24 hours) and then re‑measure the contact angle and the finger‑print visibility. We report the chemical resistance and the retention of the repellency.

Optical Performance Testing – Evaluating the Clarity and Transparency

Grease resistance is not only about repellency but also about maintaining the optical clarity of the screen. Our tests measure the haze, the clarity, and the light transmission before and after the application of grease, providing a comprehensive assessment of the screen's visual quality.

• Haze and clarity measurement (ASTM D1003 / NTC 5640 – for the optical quality) – we measure the haze (in %) and the clarity (in %) of the screen surface using a haze meter. The measurement is performed before and after the application of a controlled amount of grease (or a fingerprint). The increase in the haze is a measure of the grease‑induced degradation of the optical quality. We report the haze and the clarity before and after the grease application.
• Light transmission measurement (ASTM D1003 / NTC 5641 – for the transparency) – we measure the total light transmission (in %) of the screen surface before and after the grease application. The reduction in the transmission is correlated with the fingerprint visibility. We report the light transmission before and after the grease application.
• Reflectance measurement (NTC 5642 – for the anti‑reflection performance) – we measure the specular reflectance (in %) of the screen surface at a specified angle (e.g., 60°) before and after the grease application. The increase in the reflectance is a measure of the grease‑induced glare. We report the reflectance before and after the grease application.
• Image contrast and readability test (NTC 5643 – for the visual performance under ambient light) – we place a test image (e.g., a standard resolution chart or a text page) behind the screen and evaluate the contrast and the readability under ambient light (e.g., 500 lux). The test is performed with and without a fingerprint on the screen. We report the contrast ratio and the readability rating.
• Fingerprint induced haze measurement (NTC 5644 – for the quantitative haze evaluation) – we apply a standardized fingerprint to the screen surface and measure the haze and the clarity of the fingerprint area using a micro‑haze meter. The haze increase (ΔH) is calculated. We report the ΔH and the visibility rating.

Complementary Tests – Hardness, Thickness, and Material Identification

To fully understand the grease resistance performance and to correlate it with the coating properties, we perform complementary tests, including pencil hardness, coating thickness, and material identification.

• Pencil hardness test (ASTM D3363 / ISO 15184 / NTC 5650 – for the coating hardness) – we measure the pencil hardness (from 9B to 9H) of the screen coating to evaluate its resistance to scratching. A harder coating is generally more durable and may have better grease resistance. We report the pencil hardness rating.
• Coating thickness measurement (NTC 5651 – for the layer thickness) – we measure the thickness of the anti‑fingerprint coating (in nm) using a spectroscopic reflectometer or an ellipsometer. The thickness is correlated with the grease resistance and the durability. We report the coating thickness and the uniformity.
• FTIR spectroscopy (ASTM E168 / NTC 5652 – for the chemical composition of the coating) – we use Fourier‑transform infrared spectroscopy (FTIR) to identify the chemical composition of the anti‑fingerprint coating (e.g., fluoropolymer, siloxane, or other organic materials). The chemical composition is correlated with the grease repellency. We report the FTIR spectra and the chemical identification.
• X‑ray photoelectron spectroscopy (XPS – NTC 5653 – for the surface chemistry) – we use XPS to analyze the surface chemistry of the coating (the elemental composition and the chemical states). The surface chemistry is correlated with the surface energy and the grease resistance. We report the XPS results and the surface chemistry.
• Optical microscopy (NTC 5654 – for the surface morphology) – we use an optical microscope (or a digital microscope) to examine the surface morphology of the coating and to detect any defects (e.g., pinholes, cracks, or contamination). We report the surface images and the defect analysis.

Test Report and Recognition in the Croatian Consumer Electronics, Automotive, and Medical Sector

All procedures described are within the scope of our ISO/IEC 17025 accreditation, with equipment calibrated periodically (goniometers, profilometers, haze meters, and abrasion testers) 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 screen sample (manufacturer, model, coating type, and dimensions).
• Detailed description of the test methods applied (ASTM/ISO/IEC/HRN EN/NTC standards, test conditions, and measurement parameters).
• Numerical results: contact angle (°), surface energy (mN/m), fingerprint visibility rating (0‑5), haze (%), clarity (%), light transmission (%), coating thickness (nm), pencil hardness, and property retention after aging (%).
• Graphical data: contact angle images, surface topography maps, and haze vs. abrasion cycles curves.
• Comparative tables against the values specified by the client or against the limits of the relevant standards (ASTM D5946, ASTM F1854, ISO 25178, HRN EN ISO 25178, and the requirements of the HZN, Ministarstvo gospodarstva, and Državni inspektorat).
• Photographs of the test setup, the contact angle images, the fingerprint visibility, and the surface topography.
• Recommendations for material selection, coating optimization, and quality control measures to achieve the required grease resistance and durability.
• 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 gospodarstva i održivog razvoja for industrial and consumer product 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 displays, touch panels, and screen protectors. Additionally, we offer consulting services for the selection of anti‑fingerprint coatings, the design of durable screen surfaces, and the implementation of quality control programs for grease resistance, contributing to the user experience, hygiene, and reliability of electronic devices in the diverse and growing Croatian market, from the consumer electronics and automotive sectors to the medical and industrial display applications.