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AATCC . Purpose and Scope energy for which the wavelengths of the 6. NOTE: The limits of the spectral range of ultraviolet radiation are not well defined and may vary according to the user. Committee E Instrument Verification and Calibration 7. Calibrate the spectrophotometer or spectroradiometer according to manufacturer instructions. The use of physical standards are recommended for validating the measurement of spec- 2. Principle Calibrate the wavelength scale of the spectrophotome- intervals.
Safety Precautions 2. The wavelength erythemally weighted ultraviolet radiation UV-R irradiance at the detector for information purposes only. Reference wavelengths for both mercury arc emission and holmium oxide absorption are 2. All OSHA standards and rules 7. Set the tive spectral effectiveness for the relevant must also be consulted and followed. Vali- irradiance at the detector with a specimen be followed.
Wear prescribed safety date the linearity of the transmittance present is equal to the summation be- glasses in all laboratory areas. Uses and Limitations tive spectral effectiveness for the relevant screens supplied by the instrument manufacturer or standardizing laboratories.
Specimens times the wavelength interval. Terminology 3. However, the techniques for stretching the specimens are not part of this method and are addressed in a separate test procedure. It must be noted that stretching the specimens could change the UPF properties. Avoid distorting the specimen during preparation and han- of the skin sunburn due to capillary 6. Apparatus and Materials congestion as in inflammation. UPF , n. Conditioning 9.
Procedure Record the individual measurements. Thoroughly wet out the specimen in distilled water by placing it flat in the bottom of a beaker and then pour distilled water into the beaker until the specimen is covered.
Allow the specimen to remain submerged for 30 minutes. Press and move the specimen from time to time to ensure a good and uniform penetration. Prepare only one specimen at a time. If the fabric has low moisture absorption, repeat the soaking and wringing steps. Note, some samples may not be capable of achieving the specified wet pick-up such as tightly woven synthetic fabrics. Avoid evaporative reduction of the moisture content below the specified level before the actual UV transmission measurements are made.
Calculations Report Precision and Bias The average UPF was Between-laboratory precision has not been established for this test method. Until such precision information is available, users of the method should use standard statistical techniques in making any comparison of test results for betweenlaboratory averages. Transmittance or blocking of erythemally weighted ultraviolet radiation through fabrics can be defined only in terms of a test method.
There is no independent method for determining the true value. As a means of estimating this property, the method has no known bias.
References Notes The integrating sphere surface is internally coated or constructed using a material that is both diffuse and highly reflecting in the ultraviolet region.
Illumination and viewing geometries. In this geometry the specimen is illuminated with an unidirectional beam whose axis is not greater than 0. Any ray of this beam shall not exceed 0. The cross-sectional area of the illuminating beam shall be at least 10 times the dimension of the largest hole in the test material.
The total flux transmitted by the specimen is collected by the integrating sphere. In this geometry the specimen is illuminated by an internally illuminated integrating sphere. The specimen is viewed unidirectionally with an axis not greater than 0.
The cross-sectional area of the viewing beam shall be at least 10 times the dimension of the largest hole in the test material. The error can be eliminated in either geometry by use of a separate reference beam that traverses its own port opening in the sphere.
The reference beam impinges on either a portion of the sphere wall or a reference material mounted at a diametrically opposed port opening.
Spectral requirements. The spectrophotometer or spectroradiometer shall have a spectral bandpass of 5 nm or less over the spectral range of nm or less to nm or more. The measured wavelength interval over this spectral range should not be greater than 5 nm. Stray radiation. The contribution of stray radiation within the instrument, including that due to sample fluorescence, shall produce an error of less than 0.
Sample fluorescence. The contribution of sample fluorescence on spectral transmittance measurements on certain dyes and whitening agents present in fabrics that may fluoresce could result in artificially high values of spectral transmittance. This includes nearly all wavelengths in the UVR spectral region. The error due to the fluorescence can be removed by placing a UV transmitting, visible blocking filter after the sample.
A Schott Glass UG11 filter has been found to be satisfactory. However, the decrease in transmission of the filter with increasing wavelength may reduce the usefulness of the long wavelength UVA measurement.
In spectrophotometers and spectroradiometers where the illumination is polychromatic and the monochromator follows the specimen in the optical path, the artificially high values of transmittance appear at the emission wavelengths of the fluorescing agent.
The effects of fluorescence are, therefore, eliminated at most UVR wavelengths. The use of an illuminating light source that conforms to the spectral distribution requirements for solar simulators will most accurately include the contribution of sample fluorescence to the long wavelength UVA measurement.
However, because the fluorescent component does not contribute to the UPF, the spectral distribution of the source is irrelevant, so long as it provides sufficient energy to cover the spectral range of interest to acceptable signal to noise ratios in the spectral data.
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American Standards for UV-Protective Textiles
UV Resistance / Protection Test: AATCC 183 , ASTM D655, ASTM D6603