ASTM D823 PDF

Akinoran If the coating thickness is too high, coat another panel using a smaller blade clearance. NOTE 13—The width of the spray pattern should be considerably wider than the width of the test panel to assure spray uniformity on the test panel. NOTE 3—Suitable traverse speeds for automative coatings usually range from If the coating thickness is too high, coat another panel with fewer passes of the spray pattern or, if this is not feasible, reduce the material further with thinner. If the coating thickness is too high, select an applicator blade with a smaller clearance and coat another panel. Place the auxiliary bar in front of the pool of material see Fig.

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A number in parentheses indicates the year of last reapproval. This standard has been approved for use by agencies of the U. Department of Defense. The values given in parentheses are mathematicalconversions to SI units that are provided for information onlyand are not considered standard.

It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.

Referenced Documents2. For the purpose of measuring specular gloss, thestandard surface is polished glass. Summary of Test Method4.

The geometry of angles and apertures is chosen so thatthese procedures may be used as follows Significance and Use5. Measurements by this test method correlate with visualobservations of surface shininess made at roughly the corre-sponding angles. Since specularreflectance depends also on the surface refractive index of thespecimen, the measured gloss ratings change as the surfacerefractive index changes. In obtaining the visual gloss ratings,however, it is customary to compare the specular reflectancesof two specimens having similar surface refractive indices.

Current edition approved Jan. Published January Originallyapproved in Last previous edition approved in as D — United States1both distinctness-of-image gloss and reflection haze. TestMethod D provides an alternative procedure for measur-ing reflection haze. However, in many applications the gloss scales of this testmethod have provided instrumental scaling of coated speci-mens that have agreed well with visual scaling The receptor shall be a photosensitive device responding tovisible radiation.

The axis of the receptor shall be at themirror reflection of the axis of the incident beam. The axis ofthe incident beam and the axis of the receptor shall be within0. With a flatpiece of polished black glass or other front-surface mirror inthe specimen position, an image of the source shall be formedat the center of the receptor field stop receptor window. Thelength of the illuminated area of the specimen shall be not morethan one third of the distance from the center of this area to thereceptor field stop.

The dimensions and tolerance of the sourceand receptor shall be as indicated in Table 1. The angulardimensions of the receptor field stop are measured from thereceptor lens in a collimated-beam-type instrument, as illus-trated in Fig. See Fig. Thetolerances are chosen so that errors in the source and receptorapertures do not produce an error of more than one gloss unitat any point on the scale 5. NOTE 1—The parallel-beam glossmeters possess the better uniformityof principle-ray angle of reflection, but the converging-beam glossmeterspossess the better uniformity in extent of angular divergence accepted formeasurement.

NOTE 2—Polarization—An evaluation of the impact of polarization ongloss measurement has been reported The magnitude of the polar-ization error depends on the difference between the refractive indices ofspecimen and standard, the angle of incidence, and the degree ofpolarization. Because the specimen and standard are generally quitesimilar optically, measured gloss values are little affected by polarization. Since specular reflection is, ingeneral, spectrally nonselective, spectral corrections need to beapplied only to highly chromatic, low-gloss specimens uponagreement of users of this test method.

Reference Standards7. Thegloss value for glass of any other refractive index can becomputed from the Fresnel equation 5. For small differencesin refractive index, however, the gloss value is a linear functionof index, but the rate of change of gloss with index is differentfor each geometry. Each 0. For example, glass of index 1. Such standards should bechecked periodically for constancy by comparing with primarystandards. Keep them clean and away from any dirt that might scratch ormar their surfaces.

Never place standards face down on asurface that may be dirty or abrasive. Always hold standards atthe side edges to avoid getting oil from the skin on the standardsurface. Clean the standards in warm water and a milddetergent solution brushing gently with a soft nylon brush.

Do not wipe standards. Thepolished black glass high-gloss standard may be dabbed gentlywith a lint-free paper towel or other lint-free absorbentmaterial. Place the rinsed standards in a warm oven to dry. Preparation and Selection of Test Specimens8. Whenever a test for gloss requires the preparation of testspecimens, use the procedures given in Practice D Instrument Calibration9.

If the reading is not within To calibrate, adjust the instru-ment to read correctly the gloss of a highly polished standard,properly positioned and oriented, and then read the gloss of aworking standard in the mid-gloss range.

If the instrumentreading for the second standard does not agree within one unitof its assigned values, check cleanliness and repeat. If theinstrument reading for the second standard still does not agreewithin one unit of its assigned value, repeat with anothermid-range standard. If the disparity is still more than one unit,do not use the instrument without readjustment, preferably bythe manufacturer. For specimens with brush marks or similar textureeffects, place them in such a way that the directions of themarks are parallel to the plane of the axes of the incident andreflected beams.

If the range is greater thantwo gloss units, take additional readings and calculate the meanafter discarding divergent results as in the section on Test forOutliers of Practice D For larger specimens, take aproportionately greater number of readings. For non-idealsamples, for example, weathered samples the parties involvedshall determine the acceptable range. Diffuse Correction To apply the correction,subtract it from the glossmeter reading.

To measure thecorrection, illuminate the specimen perpendicularly and viewat the incident angle with the receiver aperture specified in 6.

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ASTM D823:18

A number in parentheses indicates the year of last reapproval. This standard has been approved for use by agencies of the U. Department of Defense. The values given in parentheses are mathematicalconversions to SI units that are provided for information onlyand are not considered standard. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use. Referenced Documents2.

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BEVS 1818 ASTM D823 Automatic Film Applicator

A number in parentheses indicates the year of last reapproval. This standard has been approved for use by agencies of the U. Department of Defense. The values given in parentheses are for informationonly. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use. Referenced Documents2.

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Download: Astm D823 Pdf.pdf

Vudojora A mechanism shall be provided to stop the blade movement asttm at the end of the draw-down. The panel holder or the gun mount traverse speed shall be adjustable from 7. The viscosity range for normal? It is particularly important that it be used in the evaluation of metallic coatings for appearance properties, such as gloss and color. It is usually less reliable for producing uniform? Place the auxiliary bar in front of the pool of material see Fig.

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