3.3  LIGHT RESISTANCE 

3.3.1  Scope

This test measures the ability of laminate flooring to retain its color when exposed to a light source having a frequency range approximating sunlight through window glass.  It is not intended to show the resistance to continuous exposure to outdoor weathering conditions. 

3.3.2    Test Apparatus

3.3.2.1       Xenon-arc light source capable of providing electromagnetic energy approximating sunlight with a spectral bandpass of approximately 280 to 800 nm with filtering appropriate to simulate sunlight through a window.

3.3.2.2       Environmental Chamber maintained at 23^oC + 3^oC (73^oF + 5^oF) and relative humidity of 50% + 5%.

3.3.2.3       Overhead lighting consisting of cool white fluorescent light with the bulbs positioned parallel to the line of sight and providing an intensity of 800 to 1100 lux (75 to 100 foot-candles) at the specimen surface when examined. 

3.3.3  Specimens

3.3.3.1    The test specimen shall be of the size required by the sample holder of the Xenon-arc test apparatus. 

3.3.4  Procedure

3.3.4.1       Condition the specimen for at least 24 hours prior to the test at a temperature of 23^oC + 3^oC (73^oF + 5^oF) and relative humidity of 50% + 5%.

3.3.4.2       Mount the specimen in a masked holder such that approximately ½ of the sample face to be tested is covered and the other half is exposed to the light source.

3.3.4.3       Operating set points for the exposure shall be as follows:

3.3.4.3.1 Black Panel Temperature            70^oC + 3^oC (158^oF + 5^oF)

3.3.4.3.2 Dry Bulb Temperature*               50^oC + 3^oC (122^oF + 5^oF)

3.3.4.3.3Wet Bulb Temperature                39^oC + 1^oC (102^oF + 2^oF) to maintain 50% (+ 5%) Relative Humidity

3.3.4.3.4 Conditioning Water                     20^oC + 3^oC (68^oF + 5^oF)

3.3.4.3.5 Duration of Exposure                  72 hours + 0.5 hour

3.3.4.3.6 Calibration wavelength                420 nm

3.3.4.3.7 Rate of Irradiance                       1.10 W/m² + 0.03 W/m²

3.3.4.3.8 Total Irradiance                          285.12 kJ/m² + 2.00 kJ/m²

3.3.4.3.9 Automatic control of power to the light source to maintain a constant irradiance level and accommodate for aging effect of light sources and solarization of filters.

*Note:     The Black Panel Temperature is the primary controlled temperature and the Dry Bulb Temperature is secondary control.

3.3.4.4       Expose the specimen to the light source as outlined in 3.3.4.3.

3.3.4.5       At the conclusion of the exposure period, remove the specimen from the holder and allow to recover for 24 hours + 1 hour without exposure to light at a temperature of 23^oC + 3^oC (73^oF + 5^oF) and relative humidity of 50% + 5%.

3.3.4.6       At the conclusion of the recovery period examine the specimen by placing it, without preinspection, on a horizontal surface having the illumination as outlined in 3.3.2.3 and then viewing the specimen at an eye-to-specimen distance of approximately 750 to 900 mm (30 to 36 inches) and at an angle of approximately 45^o to 75^o from the horizontal plane.  The specimen shall be rotated in the horizontal plane and viewed from all directions.  Light sources other than that outlined in 3.3.2.3 which can accentuate or minimize effects, shall be avoided.

3.3.4.7       Grade the specimen as follows:

No effect - no change in color or surface finish.

Slight effect - a change in color or surface finish visible only at certain angles and directions.

Moderate effect - a change in color or surface finish visible at all angles and a direction but does not notably alter the original condition of the specimen.

Severe effect - a change in color or surface finish which markedly alters the original condition of the specimen. 

3.3.5  Report

3.3.5.1       Reference to this standard.

3.3.5.2       Description of the material under test.

3.3.5.3       The light resistance.

3.3.5.4       Any deviation from the specified test method.

3.3.5.5       Date of the test. 

3.3.6  Precision & Bias

3.3.6.1    Because the measurement outcome for this test is a discrete result and subjective in nature, precision and bias cannot be determined. 

Back to NALFA Table of Contents