Bottle decolorization experiment

Bottle Decolorization Experiment – Accredited ISO/IEC 17025 Testing Services for the Colombian Market

The bottle decolorization experiment is a critical quality control test used to evaluate the resistance of plastic, glass, and coated containers to color change, fading, or staining when exposed to light, heat, chemicals, and food simulants. This property is especially important for bottles used in the beverage, pharmaceutical, cosmetic, and food industries, where product appearance, consumer perception, and regulatory compliance depend on consistent color stability. In the Colombian market, the Instituto Nacional de Vigilancia de Medicamentos y Alimentos (INVIMA), the Superintendencia de Industria y Comercio (SIC), and the Dirección de Impuestos y Aduanas Nacionales (DIAN) enforce strict quality and safety standards for packaging materials, including colorfastness and migration limits. Our laboratory offers a comprehensive bottle decolorization testing service, applying standardized methods that simulate real-world exposure conditions (UV radiation, heat, humidity, and chemical contact) and measure the degree of color change using spectrophotometry, visual inspection, and color difference indices (ΔE*). All tests are performed under our ISO/IEC 17025 (CNAS) accreditation, and the resulting reports are fully accepted by Colombian authorities, making them essential for product certification, quality control, and import-export processes.

Bottle Samples We Regularly Test

Our laboratory receives a wide variety of bottles and containers for decolorization experiments. Typical samples include:

• PET bottles – for carbonated and non-carbonated beverages, water, and edible oils.
• Glass bottles – for alcoholic beverages, pharmaceuticals, and cosmetics.
• HDPE and PP bottles – for detergents, chemicals, and food products.
• Multilayer and coated bottles – with barrier layers or UV-protective coatings.
• Colored and tinted bottles – for light-sensitive products (e.g., beer, essential oils, medicines).
• Bottles with printed labels and decorations – to evaluate the color stability of the entire packaging.
• Prototype and new bottle designs – submitted by manufacturers for color stability validation before series production.
• Bottles retrieved from field storage – for assessment of color change after long-term exposure.

Accelerated Light Exposure and UV Aging – Simulating Sunlight and Fluorescent Light

Light exposure is one of the primary causes of color fading and yellowing in bottles, especially in clear or lightly tinted plastics. Our accelerated light exposure tests simulate the effects of sunlight and indoor lighting on bottle color, following international standards and the requirements of the INVIMA for packaging used in food and drug products.

• UV aging test with UVA-340 fluorescent lamps (ASTM G154 / ISO 4892-3 / NTC 5200) – bottle samples (flat sections or whole bottles, depending on the test setup) are placed in a UV exposure chamber equipped with UVA-340 lamps (which simulate the short-wavelength UV region of sunlight). The samples are subjected to cycles of UV exposure (at 60 °C) and condensation (at 50 °C) for specified durations: 100, 200, 500, and 1000 hours. After each exposure period, the color of the bottle is measured using a spectrophotometer (CIELAB color space). The total color difference (ΔE*) is calculated. We report the ΔE* values at each exposure time and the time to reach a ΔE* of 2 (the threshold for noticeable color change). This test is critical for bottles stored in outdoor or brightly lit environments.
• Xenon arc light exposure (ASTM G155 / ISO 4892-2 / NTC 5201 – for simulating full solar spectrum) – for a more realistic simulation of sunlight (including visible and infrared), we use a xenon arc lamp with appropriate filters. The test cycle includes light exposure, dark periods, and water spray (to simulate rain). The bottle samples are exposed for 200, 500, and 1000 hours, and the color difference (ΔE*) is measured. We report the ΔE* values and the visual appearance of the bottles.
• Accelerated UV aging with QUV weathering (NTC 5202 – for bottles with UV stabilizers) – this test is similar to ASTM G154 but performed with a QUV weathering tester, which provides a controlled and reproducible UV exposure. We report the color difference (ΔE*) and any surface cracking or chalking (visual inspection).
• Light exposure with fluorescent lamps (simulating indoor lighting) – NTC 5203 – bottles are exposed to cool white fluorescent lamps (1000 lux) at 23 °C for 500, 1000, and 2000 hours. This simulates the conditions of retail stores and warehouses. We report the ΔE* values and the visual appearance.
• Color stability after UV exposure with and without UV blockers (NTC 5204 – evaluation of UV stabilizer effectiveness) – for bottles with added UV blockers (e.g., in beer bottles or sunscreen containers), we compare the decolorization behavior of bottles with and without the UV stabilizer. We report the ΔE* values for both sets and the relative improvement (or degradation) provided by the stabilizer.

Heat and Thermal Aging Tests – Simulating Storage and Transportation Conditions

Elevated temperatures during storage, transportation, or hot-filling processes can accelerate color change in bottles, especially in plastics containing dyes, pigments, or additives. Our heat and thermal aging tests evaluate the color stability of bottles under thermal stress, following international standards and the requirements of the Colombian food and beverage industry.

• Thermal aging test at elevated temperature (ASTM D3045 / ISO 4577 / NTC 5210) – bottle samples are placed in an oven at a specified temperature (e.g., 60 °C, 70 °C, or 80 °C) for periods of 7, 14, and 28 days. The color is measured before and after the thermal exposure. We report the ΔE* values and the time to reach a ΔE* of 2 at each temperature. This test is particularly relevant for bottles that are hot-filled or stored in warm climates (e.g., coastal areas of Colombia).
• Thermal cycling test (NTC 5211 – repeated temperature changes) – the bottles are subjected to thermal cycles (e.g., 20 °C to 60 °C and back to 20 °C) with a dwell time of 2 hours at each temperature, for 10, 25, or 50 cycles. The color is measured before and after cycling. We report the ΔE* values and the visual appearance.
• Hot-fill simulation test (NTC 5212 – exposure to hot liquid) – the bottle is filled with water at 85 °C (or the specified filling temperature), held for 30 minutes, and then cooled to room temperature. This process is repeated for 5 cycles. The color is measured before and after the cycles. We report the ΔE* values and the presence of any deformation or surface cracking.
• Accelerated aging in a steam environment (NTC 5213 – for bottles used in sterilizable applications) – bottles are exposed to steam at 121 °C for 15 minutes in an autoclave (simulating the sterilization process for pharmaceutical and medical bottles). The color difference is measured before and after exposure. We report the ΔE* values and the visual condition.
• Humidity and heat combined test (ASTM D570 / NTC 5214 – 70 °C, 95 % RH) – bottles are placed in a temperature/humidity chamber at 70 °C and 95 % relative humidity for 7, 14, and 28 days. This simulates tropical conditions (common in many parts of Colombia). The color is measured, and we report the ΔE* values and the visual appearance.

Chemical Resistance and Contact with Food Simulants – Evaluating Migration and Discoloration

Bottles used for food, beverages, and cosmetics may come into contact with acidic, basic, oily, or alcoholic contents, which can cause color migration or chemical degradation of the bottle material. Our tests evaluate the color stability of bottles when exposed to food simulants, following the European and Colombian regulations for food contact materials.

• Migration test with food simulants (ASTM D4754 / EU 10/2011 / NTC 5220 – for food contact bottles) – bottle samples are immersed in food simulants: 3 % acetic acid (simulating acidic foods), 10 % ethanol (simulating aqueous alcohol), and vegetable oil (simulating fatty foods) at 40 °C, 60 °C, or 100 °C for 10 days. The color of the bottle sample and the color of the simulant are measured before and after immersion. We report the ΔE* of the bottle, the change in color of the simulant, and the overall migration of colorants.
• Resistance to acidic and alkaline solutions (NTC 5221 – for cosmetic and chemical bottles) – bottles are immersed in 10 % HCl, 10 % NaOH, and a 5 % NaCl solution for 7 days at 23 °C. The color difference (ΔE*) of the bottle is measured, and the surface is visually inspected for discoloration, cracking, or leaching. We report the ΔE* values and the visual condition.
• Resistance to oils and solvents (ASTM D471 / NTC 5222 – for bottles containing oils, essential oils, or solvents) – bottles are immersed in mineral oil, olive oil, and isopropanol at 23 °C for 7 days. The color difference is measured. We report the ΔE* values and the compatibility of the bottle material with these substances.
• Chemical spotting test (NTC 5223 – spot test for localized chemical attack) – a few drops of the test chemical (e.g., acetic acid, ethanol, NaOH) are placed on the bottle surface and left for 24 hours. The spot area is inspected for discoloration or staining. We report the result (pass/fail) for each chemical.
• Combined chemical and UV exposure test (NTC 5224 – for outdoor use bottles) – bottles are exposed to UV radiation while being immersed in water or a chemical solution, to evaluate the synergistic effect of light and chemicals. We report the ΔE* values and the surface condition.

Visual Assessment and Spectrophotometric Measurement – Quantifying Color Change

Objective color measurement is essential for determining the degree of decolorization and for classifying the bottle's performance. We use both visual and instrumental methods to assess color change, following international standards and the requirements of the Colombian packaging industry.

• Spectrophotometric measurement of color (ASTM D2244 / ISO 11664 / NTC 5230) – we measure the color of the bottle sample (in the CIELAB color space) using a spectrophotometer with a D65 illuminant and a 10° observer. The measurements are taken at multiple points on the bottle surface. Before and after the exposure test, the L*, a*, and b* coordinates are recorded. We calculate the total color difference ΔE* = √[(ΔL*)² + (Δa*)² + (Δb*)²]. We report the ΔE* values and the individual L*, a*, b* changes.
• Yellowness index measurement (ASTM D1925 / NTC 5231 – for transparent and translucent bottles) – for clear or lightly tinted bottles, we measure the yellowness index (YI) before and after exposure. The YI is a measure of the shift toward yellow, which is a common degradation mode in plastics. We report the ΔYI (change in yellowness index).
• Visual inspection under standardized lighting (ASTM D1729 / NTC 5232 – color matching under controlled light) – the exposed and unexposed bottle samples are placed side by side in a light booth with D65 (daylight) and A (incandescent) illuminants. A panel of trained evaluators (at least 3) visually assesses the color difference and assigns a rating using the Gray Scale for color change (ISO 105-A02: 1 to 5, where 5 = no change). We report the average Gray Scale rating and the visual notes.
• Opacity and haze measurement (ASTM D1003 / NTC 5233 – for translucent bottles) – for bottles that may become hazy or cloudy after exposure, we measure the haze (%) and the clarity before and after the test. We report the Δhaze and the visual appearance.
• Gloss measurement (ASTM D523 / NTC 5234 – for printed or coated bottles) – for bottles with external coatings or decorative prints, we measure the gloss (in GU) before and after exposure, and we report the change in gloss.

Complementary Analyses – Material Identification and Failure Analysis

For a complete understanding of the decolorization mechanism and to identify the root cause of color change, we complement the color tests with material characterization analyses, which are essential for quality improvement and for meeting the requirements of the INVIMA and SIC for packaging materials.

• FTIR spectroscopy for polymer identification (ASTM E168 / NTC 5240) – we analyze the bottle material (PET, HDPE, PP, glass, etc.) to confirm its identity and to detect the presence of additives, plasticizers, or stabilizers that may affect color stability.
• UV-Vis spectrophotometry of the bottle material (NTC 5241 – for detecting colorants and UV stabilizers) – we measure the UV-Vis absorbance spectrum of the bottle material to detect the presence of colorants and UV stabilizers, and to evaluate their degradation after exposure.
• Thermogravimetric analysis (TGA) – ASTM E1131 / NTC 5242 – we measure the thermal stability and the content of fillers and additives (e.g., titanium dioxide, carbon black) that can influence the color stability.
• Differential scanning calorimetry (DSC) – ASTM D3418 / NTC 5243 – we measure the glass transition temperature (Tg) and the melting point of the polymer to detect any degradation or crosslinking that may affect color.
• Microscopic examination of the surface (SEM – ASTM E1508 / NTC 5244) – we inspect the bottle surface before and after exposure to detect surface cracks, crazing, or phase separation, which can enhance color fading or yellowing.

Test Report and Recognition in the Colombian Packaging and Consumer Goods Sector

All procedures described are within the scope of our ISO/IEC 17025 accreditation, with equipment calibrated periodically (UV chambers, spectrophotometers, ovens, and glossmeters) and traceability to international standards (NIST, PTB). Our test reports are issued in Spanish and include:

• Full identification of the bottle sample (material, manufacturer, lot number, color, thickness, and intended use).
• Detailed description of the test methods applied (ASTM/ISO/NTC standards, exposure conditions, temperature, duration, and test parameters).
• Numerical results: ΔE* values, YI, ΔYI, Gray Scale rating, Δhaze, and Δgloss for each exposure condition and time point.
• Graphical data: ΔE* vs. exposure time, YI vs. exposure time, and color space plots (L*a*b*).
• Comparative tables against the values specified by the client or against the limits of the NTC 5200 (UV aging), NTC 5210 (Thermal aging), NTC 5220 (Food simulant migration), and the requirements of the INVIMA, SIC, and DIAN for packaging certification.
• Photographs of the bottles before and after the tests, showing the visible color differences.
• Recommendations for improving color stability (e.g., adding UV stabilizers, using higher-quality colorants, optimizing molding parameters, or changing the bottle material).
• Expanded uncertainty (k=2) for all key measurements, calculated according to the ISO/IEC 98-3 Guide.

These reports are fully accepted by the Instituto Nacional de Vigilancia de Medicamentos y Alimentos (INVIMA) for the registration and certification of packaging materials for food, beverages, and pharmaceuticals, by the Superintendencia de Industria y Comercio (SIC) for product quality and safety compliance, and by the Dirección de Impuestos y Aduanas Nacionales (DIAN) for tariff classification and quality verification in the import of bottles and packaging materials. Additionally, we offer consulting services for the selection of color-stable materials, the design of packaging with high UV resistance, and the implementation of quality control programs to ensure consistent color performance, contributing to the quality, safety, and brand reputation of products in the diverse and demanding Colombian market, from the high-end cosmetic bottles to the everyday beverage containers.