ASTM D2457 PDF

A number in parentheses indicates the year of last reapproval. It contains four separate gloss angles Note 1 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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A number in parentheses indicates the year of last reapproval. It contains four separate gloss angles Note 1 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. Significance and Use4. Precise comparisons ofgloss values are meaningful only when they refer to the samemeasurement procedure and same general type of material. Inparticular, gloss values for transparent films should not becompared with those for opaque films, and vice versa.

Gloss isa complex attribute of a surface which cannot be completelymeasured by any single number. It is sometimes used for comparative measure-ments of these surface properties. The receptor shall be a photosensi-tive device responding to visible radiation.

The axis of the receptor shall be at themirror reflection of the axis of the incident beam. With a flatpiece of polished black glass or other front-surface mirror inspecimen position, an image of the source shall be formed atthe center of the receptor field stop receptor window. Thelength of the illuminated area of the specimen shall be equal tonot more than one third of the distance from the center of thisarea to the receptor field stop.

The angular dimensions andtolerances of the geometry of the source and receptor shall beas indicated in Table 1. The angular dimensions of the receptorfield stop are measured from the center of the test surface. Current edition approved April 1, Published April Originallyapproved in United States1angular dimensions of the source field stop are mostly easilymeasured by the specimen-to-window angular size of themirror image of the source formed in the receptor field stop.

See Fig. The tolerances are chosen so that errors of no more than onegloss unit at any point on the scale will result from errors in thesource and receptor aperture. Since specular reflection is, ingeneral, spectrally nonselective, spectral corrections need beapplied only to highly chromatic, low-gloss specimens uponagreement of users of this test method. Reference Standards6. Multiply the computed Rsat each angle by the scale factorsshown in Table 2.

Preparation and Selection of Test Specimens7. Whenever a test for gloss requires the preparation of a testspecimen, report the technique of specimen preparation. Ensure that specimensurfaces have good planarity. Perform tests with the directionsof machine marks, or similar texture effects, both parallel andperpendicular to the plane of the axes of the incident andreflected beams, unless otherwise specified. Note that thisdoes not avoid the second-surface reflection.

Gloss is due chiefly to reflection at the surface; therefore,anything that changes the surface physically or chemically islikely to affect gloss. Mounting Films for Measurement8. Three different filmholding devices have each proved satisfac-tory for at least some types of films Connect the vacuum plate by rubber tube to a vacuum pump orvacuum line.

With thin, soft films it is sometimes necessary touse a valve and pressure gage and to limit the vacuum so as tokeep from collapsing the soft film into the pores of the groundplate. Make sure each specimen is pulled smooth, but notstretched before holding it by the two strips of adhesive tape. Replace the tape whenever it loses its adhesiveness. Push downcarefully, taking care to pull the test film taut without stretchingit. Measure the taut area. Erroneous measurements willoccur without a suitable trap or backing.

If at any time an instrumentfails to repeat readings of the standard to within 2 percent ofthe prior setting, the intervening results should be rejected. Tocalibrate, adjust the instrument to read correctly the gloss of ahighly polished standard, and then read the gloss of a standardhaving poorer image-forming characteristics.

If the instrumentreading for the second standard does not agree within 1 percentof its assigned value, do not use the instrument withoutreadjustment, preferably by the manufacturer.

NOTE 5—Correct readings on black-glass and intermediate standards donot guarantee instrument conformity to specification requirements. Inaddition to measurements with gloss standards, dimensional checks forconformity to the geometric requirements of 4.

Clear plastic films have two specularly reflect-ing surfaces. Even though they are less than perfectly smoothand less than 1. For specimenswith extrusion lines or other direction texture effects, orient themarks both parallel and perpendicular to the plane of the axesof the incident and reflected beams.

Measure at least threeportions of the specimen surface in each direction to obtain anindication of uniformity. If no directionality is detected in thespecimen, then the test may be performed only in the parallelor perpendicular orientation. NOTE 6—In the case of films, it is often desirable to compare thesereadings with readings taken across the machine direction. Difference inthe readings will relate to the prominence of the machine marks.

NOTE 7—Diffuse Correction—It can be said that the light reflected bya specimen may be divided into one part reflected specularly in thedirection of mirror reflection associated with gloss and another partreflected diffusely in all directions associated with lightness on thewhite-gray-black scale. According to this picture, a gloss reading alwaysneeds to be diminished to compensate for that amount of the measuredlight attributable to diffuse reflectance.

Ifdiffuse corrections are desired as additional information, measure deg,0-deg luminous directional reflectances of specimens in accordance withTest Methods E or E Multiply reflectance values in percentageby the following factors3for diffuse corrections in gloss unitsdeg 0. Precision and Bias The test results in Table 3 were from 13 labs;Table 4 from seven labs and Table 5 from five labs.

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ASTM D2457 PDF

Vimuro It contains four separate gloss angles Note 1: Connect with us for your business enquiries. The ASTM D standard test method is used to measure the gloss of solid plastics and plastic films opaque satm transparent both. Through our network of over 43, people in 1, laboratories and offices in countries, Intertek provides quality and safety solutions to a wide range of industries around the world. Specular Gloss is a measure of the light reflected by the surface of a material.

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Glossmeter

Vujinn Assurance Enabling you to identify and mitigate the intrinsic risk in your operations, supply chains and business processes. Thus Gloss can be useful in product development, process development, and end use performance testing. Evaluating how your asrm and services meet and exceed quality, safety, sustainability and performance standards. Specular Gloss is a measure of the light reflected by the surface of a material. Auditing Consulting Sourcing Training. Certification Formally confirming that your products and services meet all trusted external and internal standards.

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Connect with us for your business enquiries. Certification Formally confirming that your products and services meet all trusted external and internal standards. It is sometimes used for comparative measurements of these surface properties. Thus Gloss can be useful in product development, process development, and end use performance testing. Auditing Consulting Sourcing Training. Evaluating how your products and services meet and exceed quality, safety, sustainability and performance standards. Inspection Validating the specifications, value and safety of your raw materials, products asgm assets.

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