Light degradation performance testing service

Light Degradation Performance Testing Service – Accredited ISO/IEC 17025 Weathering and Durability Assessment for the Croatian Market

Light degradation is a critical failure mechanism that affects the performance, appearance, and service life of materials exposed to solar radiation, artificial light, and ultraviolet (UV) energy. Polymers, coatings, textiles, composites, adhesives, and packaging materials can undergo photo‑oxidation, chain scission, cross‑linking, discoloration, loss of gloss, embrittlement, and mechanical property deterioration when subjected to prolonged light exposure. In the Croatian market, where the Hrvatski zavod za norme (HZN), the Ministarstvo gospodarstva i održivog razvoja, the Državni inspektorat, and the Carinska uprava enforce strict quality, durability, and safety standards aligned with EU directives and HRN EN (Croatian standards based on European norms), the accurate evaluation of light degradation resistance is essential for product certification, supplier qualification, type testing, quality control in manufacturing, and import‑export processes. Our laboratory offers a comprehensive light degradation performance testing service, applying standardized methods such as ASTM G154, ISO 4892-3, ASTM G155, ISO 4892-2, IEC 60068-2-5, and HRN EN ISO 4892-3 to simulate the effects of sunlight, UV radiation, and artificial light on materials under controlled temperature, humidity, and irradiance conditions. We measure changes in color, gloss, tensile strength, elongation, impact resistance, and other key properties to quantify the extent of degradation and predict the service life of products. 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.

Materials and Products We Regularly Test for Light Degradation

Our laboratory receives a wide variety of materials and components for light degradation performance testing. Typical samples include:

• Plastics and polymers – polyethylene (PE), polypropylene (PP), PVC, polycarbonate (PC), polymethyl methacrylate (PMMA), polyamide (PA), and their composites for automotive, construction, and consumer goods.
• Coatings and paints – automotive clearcoats, architectural paints, powder coatings, and varnishes.
• Textiles and upholstery – synthetic and natural fabrics, automotive interior textiles, outdoor furniture fabrics, and awnings.
• Composites and laminates – fiber‑reinforced polymers for aerospace, marine, and wind energy applications.
• Adhesives and sealants – structural adhesives, sealants, and tapes for building and automotive applications.
• Packaging materials – films, foils, and containers for food, beverage, and pharmaceutical products.
• Automotive and transportation components – exterior trim, interior panels, headlight lenses, and dashboard materials.
• Prototype and new material formulations – submitted by manufacturers for validation of light stability before series production.
• Field‑retrieved components – for failure analysis and remaining life assessment.

UV Fluorescent Lamp Testing – Standard Method for Accelerated UV Exposure

UV fluorescent lamp testing is one of the most widely used methods for simulating the damaging effects of long‑wave UV radiation and condensation on materials. The test uses UVA‑340 or UVB‑313 lamps to replicate the UV spectrum of sunlight, with cycles of UV exposure and condensation to simulate dew formation. Our procedures follow international standards and the requirements of the Croatian construction, automotive, and coatings industries.

• UV aging test with UVA‑340 lamps (ASTM G154 / ISO 4892-3 / HRN EN ISO 4892-3 / NTC 5800 – for general materials) – we place the test specimens in a UV weathering chamber equipped with UVA‑340 lamps (which simulate the short‑wavelength UV region of sunlight). The specimens are exposed to cycles of UV light at a specified irradiance (typically 0.35 to 0.89 W/m² at 340 nm) and temperature (typically 60 °C during UV and 50 °C during condensation), and alternating condensation (water vapour) periods. The test is performed for durations of 100, 250, 500, 1000, or 2000 hours, depending on the specification. After exposure, we measure the changes in color (ΔE*), gloss, tensile strength, elongation, and impact resistance. We report the retention of mechanical properties and the colour change, and we classify the material according to its UV resistance.
• UVB‑313 lamp test for enhanced severity (NTC 5801 – for high‑severity screening) – for materials that require a more aggressive test (e.g., for outdoor applications in high‑intensity sunlight regions), we use UVB‑313 lamps with a higher UV output and shorter wavelengths. The test is performed under similar cycle conditions. We report the degradation results and the severity class.
• Alternating UV and condensation cycles (NTC 5802 – for simulating diurnal weathering) – we program the chamber to alternate between UV exposure (with controlled irradiance and temperature) and condensation (with high humidity) to simulate the daily cycle of sunlight and dew. Typical cycles include 8 hours of UV at 60 °C followed by 4 hours of condensation at 50 °C, repeated for the specified total exposure time. We report the cycle parameters and the test results.
• UV aging at different irradiance levels (NTC 5803 – for accelerated and natural correlation) – we adjust the irradiance level (e.g., 0.35, 0.55, or 0.89 W/m² at 340 nm) to accelerate the aging process or to match a specific natural exposure site. The acceleration factor is calculated based on the irradiance ratio. We report the acceleration factor and the predicted service life under natural conditions.
• UV aging with water spray (NTC 5804 – for simulated rain effect) – for materials that are also subjected to rain or wash‑off, we incorporate a water spray cycle (e.g., 18 minutes of spray per 2 hours of UV light) to simulate the thermal shock and leaching effects. We report the results with and without water spray.

Xenon Arc Lamp Testing – Full‑Spectrum Sunlight Simulation

Xenon arc lamp weathering provides the most realistic simulation of natural sunlight, including UV, visible, and infrared radiation. The test uses filters to match the spectral power distribution of sunlight at the earth's surface. Our procedures follow international standards and the requirements of the Croatian automotive, aerospace, and building materials sectors.

• Xenon arc weathering test (ASTM G155 / ISO 4892-2 / HRN EN ISO 4892-2 / NTC 5810 – for full‑spectrum light exposure) – we expose the test specimens to a xenon arc lamp with appropriate filters (e.g., daylight, window glass, or extended UV filters) to simulate sunlight (through glass or direct). The test chamber controls irradiance, temperature, and humidity. We use cycles of light exposure (at a specified irradiance, e.g., 0.35 to 0.55 W/m² at 340 nm), dark periods, and water spray to simulate rain. The test duration is typically 100, 500, 1000, or 2000 hours. After exposure, we measure the changes in color, gloss, mechanical properties, and surface morphology. We report the property retention and the degradation progression.
• Xenon arc with daylight filters (NTC 5811 – for outdoor applications) – we use daylight filters (borosilicate glass) to simulate sunlight at the earth's surface, including UVB and UVA. This is the standard configuration for materials used in outdoor applications. We report the test conditions and the degradation results.
• Xenon arc with window glass filters (NTC 5812 – for indoor and automotive interior applications) – we use window glass filters to simulate sunlight that has passed through window glass (which filters out UVB). This is used for materials used in indoor or automotive interior applications. We report the results for window glass filtered light.
• Xenon arc testing with controlled humidity (NTC 5813 – for moisture‑sensitive materials) – we adjust the relative humidity during the light and dark cycles to simulate the conditions of tropical or coastal environments. The test is performed at a specified humidity level (e.g., 50 %, 70 %, or 90 % RH). We report the degradation results under humid conditions.
• Xenon arc testing with color and gloss measurement at intervals (NTC 5814 – for tracking degradation kinetics) – we remove the specimens at intermediate intervals (e.g., every 100 or 200 hours) and measure the color (ΔE*) and gloss to construct degradation curves. The degradation kinetics (rate of colour change or gloss loss) are calculated. We report the degradation curves and the kinetics parameters.

Evaluation of Degradation – Mechanical, Physical, and Visual Properties

After light exposure, we perform a comprehensive evaluation of the degraded specimens to quantify the extent of damage and to verify the retention of key functional properties. Our tests follow international standards and the requirements of the Croatian automotive, construction, and consumer goods industries.

• Color measurement (ASTM D2244 / NTC 5820 – for colour change assessment) – we measure the colour coordinates (L*, a*, b*) of the specimens before and after exposure using a spectrophotometer and calculate the total colour difference (ΔE*). We also measure the yellowness index (YI) for transparent and white materials. We report the ΔE*, ΔYI, and the colour change rating.
• Gloss measurement (ASTM D523 / NTC 5821 – for surface gloss retention) – we measure the gloss (in GU) of the specimens at a specified angle (typically 60°) before and after exposure. The gloss retention (in %) is calculated. We report the gloss retention and the gloss loss.
• Tensile strength and elongation test (ASTM D638 / ISO 527 / NTC 5822 – for plastics; ASTM D412 / ISO 37 / NTC 5823 – for elastomers) – we test the tensile strength (in MPa) and elongation at break (in %) of the exposed and unexposed specimens. The retention of tensile strength and elongation is calculated. We report the tensile properties and the retention values.
• Impact resistance test (ASTM D256 / ISO 180 / NTC 5824 – for Izod impact; ASTM D5628 / NTC 5825 – for drop impact) – we measure the impact resistance (in J/m or J) of the exposed and unexposed specimens. The retention of impact resistance is reported. We report the impact energy and the retention percentage.
• Flexural and modulus test (ASTM D790 / ISO 178 / NTC 5826 – for flexural properties) – we measure the flexural strength (in MPa) and flexural modulus (in MPa) before and after exposure. The retention of flexural properties is reported. We report the flexural strength, modulus, and retention.
• Surface morphology and cracking assessment (NTC 5827 – for visual and microscopic inspection) – we inspect the surface of the specimens for cracks, crazing, blistering, chalking, or other degradation features using a magnifying glass or a microscope. We report the surface condition and the severity of any defects.

Life Prediction and Performance Classification – Correlation with Natural Exposure

Using the degradation data, we predict the service life of the material under natural outdoor conditions and classify the material according to its light stability. Our tests provide a pass/fail result and a classification based on the specified performance criteria.

• Life prediction using the Arrhenius or acceleration factor (NTC 5830 – for service life estimation) – we use the accelerated test data (the degradation rate as a function of the irradiance and temperature) to extrapolate the service life under natural conditions. The acceleration factor (the ratio of the accelerated test time to the natural exposure time) is calculated. We report the predicted service life (in years) and the acceleration factor.
• Performance classification according to the standard (NTC 5831 – for the UV resistance rating) – we classify the material according to the retention of key properties (e.g., colour retention, tensile retention) and the specified limits. For example, a material with a colour change of ΔE* < 2 and a tensile retention > 80 % after 1000 hours of UV exposure may be classified as "high UV resistance". We report the classification and the rating.
• Compliance with automotive and building standards (NTC 5832 – for the sector‑specific requirements) – we compare the measured degradation (colour, gloss, and mechanical retention) with the minimum requirements of the automotive (e.g., SAE J2527) or building (e.g., EN 927‑6) standards. We report the compliance and the pass/fail status.
• Guarantee verification (NTC 5833 – for contractual purposes) – we test the material to verify that its light degradation resistance is within the guaranteed values specified in the purchase order or the design specification. We report the measured degradation and the margin relative to the guarantee.
• Extended test report for CE marking and EU compliance (NTC 5834 – for the declaration of conformity) – we provide a comprehensive test report that includes all the measured degradation parameters, the test methods, the acceleration factor, and the compliance statement. The report is suitable for the CE marking and the declaration of conformity, as required by the EU directives. We report the compliance and the certification status.

Complementary Tests – Material Identification, Hardness, and Microstructure for Degradation Correlation

To fully understand the degradation mechanisms and to correlate them with the material properties, we perform complementary tests, including material identification, hardness testing, and microstructural examination.

• Material identification (FTIR, DSC – NTC 5840 – for polymer identification and additive analysis) – we use Fourier‑transform infrared spectroscopy (FTIR) to identify the chemical composition of the material (the polymer type, the stabilizers, and the pigments) and differential scanning calorimetry (DSC) to measure the glass transition temperature (Tg) and the melting temperature. The presence of UV stabilizers and the Tg are correlated with the light degradation resistance. We report the material identification, the stabilizer content, and the Tg.
• Hardness testing (ASTM D2240 / NTC 5841 – Shore A or Shore D for plastics and elastomers) – we measure the Shore A or Shore D hardness of the material before and after exposure. The change in hardness is correlated with the degree of cross‑linking or chain scission. We report the hardness change and the interpretation.
• Microstructural examination (SEM – ASTM E1508 / NTC 5842 – for surface and cross‑section analysis) – we use scanning electron microscopy (SEM) to examine the surface and the cross‑section of the exposed specimen to detect micro‑cracks, voids, or degradation of the filler‑matrix interface. The microstructural changes are correlated with the mechanical property loss. We report the SEM images and the microstructural changes.
• FTIR spectroscopy of the exposed surface (NTC 5843 – for chemical degradation analysis) – we use FTIR in attenuated total reflectance (ATR) mode to analyze the chemical changes (e.g., the formation of carbonyl or hydroxyl groups) on the exposed surface. The chemical changes are correlated with the colour change and the mechanical degradation. We report the FTIR spectra and the chemical changes.
• Thermogravimetric analysis (TGA) – ASTM E1131 / NTC 5844 – for thermal stability after degradation) – we use TGA to measure the thermal stability and the decomposition temperature of the material before and after exposure. The change in the thermal stability is correlated with the degree of degradation. We report the decomposition temperature and the mass loss.

Test Report and Recognition in the Croatian Industrial, Automotive, and Construction Sector

All procedures described are within the scope of our ISO/IEC 17025 accreditation, with equipment calibrated periodically (weathering chambers, colorimeters, glossmeters, universal testing machines, and analytical instruments) 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 material (manufacturer, product name, material type, and intended application).
• Detailed description of the test methods applied (ASTM/ISO/IEC/HRN EN/NTC standards, test conditions, irradiance, temperature, and duration).
• Numerical results: colour change (ΔE*), gloss retention (%), tensile strength retention (%), elongation retention (%), impact resistance retention (%), flexural property retention, and hardness change.
• Graphical data: degradation curves (colour, gloss, and mechanical properties vs. exposure time), and FTIR spectra.
• Comparative tables against the values specified by the client or against the limits of the relevant standards (ASTM G154, ISO 4892-3, ASTM G155, HRN EN ISO 4892-3, and the requirements of the HZN, Ministarstvo gospodarstva, and Državni inspektorat).
• Life prediction and performance classification (UV resistance rating, predicted service life).
• Statement of compliance and pass/fail status.
• Photographs of the specimens before and after exposure, and SEM images of the surface degradation.
• Recommendations for material selection, UV stabilizer optimization, and design improvements to enhance light stability.
• 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 energy 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 polymers, coatings, textiles, and automotive components. Additionally, we offer consulting services for the selection of light‑stable materials, the design of UV‑resistant products, and the implementation of quality control programs for light degradation resistance, contributing to the durability, safety, and reliability of products in the diverse and growing Croatian market, from the automotive and construction sectors to the consumer goods and energy industries.