ASTM C148-17 Standard Test Methods for Polariscopic Examination of Glass Containers.pdf

1、Designation: C148 17Standard Test Methods forPolariscopic Examination of Glass Containers1This standard is issued under the fixed designation C148; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A number

2、 in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the U.S. Department of Defense.1. Scope1.1 These test methods describe the determination of rela-t

3、ive optical retardation associated with the state of anneal ofglass containers. Two alternative test methods are covered asfollows:SectionsTest Method AComparison with Reference StandardsUsing a Polariscope69Test Method BDetermination with Polarimeter 10121.2 Test Method A is useful in determining r

4、etardations lessthan 150 nm, while Test Method B is useful in determiningretardations less than 565 nm.NOTE 1The apparent temper number as determined by these testmethods depends primarily on (1) the magnitude and distribution of theresidual stress in the glass, (2) the thickness of the glass (optic

5、al pathlength at the point of grading), and (3) the composition of the glass. Forall usual soda-lime silica bottle glass compositions, the effect of thecomposition is negligible. In an examination of the bottom of a container,the thickness of glass may be taken into account by use of the followingfo

6、rmula, which defines a real temper number, TR, in terms of the apparenttemper number, TA, and the bottom thickness, t:TR5 TA0.160 t!, where t is in inches, orTR5 TA4.06 t!, where t is in millimetres.This thickness should be measured at the location of the maximum ap-parent retardation. Interpretatio

7、n of either real or apparent temper num-ber requires practical experience with the particular ware being evalu-ated.1.3 The values stated in SI units are to be regarded as thestandard. The values given in parentheses are for informationonly.1.4 This standard does not purport to address all of thesaf

8、ety concerns, if any, associated with its use. 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.1.5 This international standard was developed in accor-dance with internat

9、ionally recognized principles on standard-ization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2C162 Ter

10、minology of Glass and Glass ProductsC224 Practice for Sampling Glass ContainersC1426 Practices for Verification and Calibration of Polarim-eters3. Terminology3.1 Definitions For definitions of terms used in these testmethods see Terminology C162.4. Significance and Use4.1 These two test methods are

11、provided for evaluating thequality of annealing. These test methods can be used in thequality control of glass containers or other products made ofsimilar glass compositions, where the degree of annealing mustbe verified to ensure quality products. These test methodsapply to glass containers manufac

12、tured from commercialsoda-lime-silica glass compositions.5. Sampling5.1 Methods of sampling a minimum lot from a group ofcontainers of a given type are given in Practice C224 for thevarious situations to which that method may apply.TEST METHOD ACOMPARISON WITHREFERENCE STANDARDS USING A POLARISCOPE6

13、. Apparatus6.1 Polariscope, conforming to the following requirements:1These test methods are under the jurisdiction of ASTM Committee C14 onGlass and Glass Products and are the direct responsibility of Subcommittee C14.07on Glass Containers.Current edition approved May 1, 2017. Published May 2017. O

14、riginallyapproved in 1939. Last previous edition approved in 2014 as C148 14. DOI:10.1520/C0148-17.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Doc

15、ument Summary page onthe ASTM website.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United StatesThis international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on

16、Principles for theDevelopment of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.16.1.1 The degree of polarization of the field at all pointsshall not be less than 99 %.6.1.2 The field shall be a minimum of 51 mm

17、(2 in.) indiameter greater than the diameter of the container to bemeasured. The distance between the polarizing and analyzingelements shall be sufficient to allow the inside bottle bottomsurface to be viewed through the open container finish.6.1.3 A sensitive tint plate, having a nominal optical re

18、tar-dation of 565 nm, with a variation across the field of view ofless than 5 nm and with its slow axis at 45 to the plane ofpolarization, shall be used. Such an orientation will produce amagenta background in the field of view. The brightness of thepolarized field illuminating the sample shall be a

19、 minimum of300 cd/m2.NOTE 2Color discrimination remains satisfactory with retardationsbetween 510 and 580 nm, but optimum conditions are attained at 565 nm.6.1.4 Samples must be allowed to equilibrate until the entirethickness of glass is at room temperature.7. Calibration and Standardization7.1 A s

20、et of not less than five standardized glass disks ofknown retardation stress shall be used to cover the range ofcommercial container annealing. Such disks shall be circularplates of glass not less than 76 mm (3 in.) nor more than 102mm (4 in.) in diameter. Each disk shall have a nominalretardation a

21、t the calibration point, 6.4 mm (0.25 in.) from theouter circumference of the disk, corresponding to not less than21.8 nm nor more than 23.8 nm of optical retardation. Eachdisk shall have a nominal retardation at the calibration point,6.4 mm (0.25 in.) from the PHYSICAL EDGE of the GLASSdisk, corres

22、ponding to not less than 21.8 nm nor more than23.8 nm of optical retardation. If the disk is mounted in a framethat covers the glass edge, refer to the instructions provided bythe supplier of the strain disk set with regard to the distance tothe calibration point from the frame ID. If unknown, the d

23、isksmay be removed from the frame, the calibration point markedaccordingly, and the disks placed back into their frames.8. Procedure8.1 Examination of the Bottom of Cylindrical FlintContainersView the inside bottom of the container throughthe open container finish. Rotate the container to determine

24、thelocation of the highest order of retardation color at the insideknuckle position. Compare the highest order retardation colorobserved at the bottom of the container to the retardation colorseen at the calibration point in various numbers of the standarddisks stacked one on top of the other and he

25、ld parallel to thesurface of the polarizer. Determine whether the maximumorder of retardation color in the container bottom is less thanthat in one disk, less than that in two and greater than one, lessthan that in three and greater than two, and so forth. It isseldom possible to obtain an exact mat

26、ch of the order ofretardation color scheme in the container with the referencestandards. Accordingly, record the temper number of thecontainer using the following procedure:8.1.1 Temper Number DeterminationWhen a maximumorder retardation color observed in the container bottom isgreater than that of

27、N disks but less than N + 1 disks, theapparent temper grade is judged to be that of N + 1 disks. Theapparent temper number is always determined to be the nextintegral temper number greater in value than the actualobserved value as seen in the following table:Apparent Temper Number Observed Temper1 l

28、ess than 1 disk2 less than 2, greater than 1 disk3 less than 3, greater than 2 disks4 less than 4, greater than 3 disks5 less than 5, greater than 4 disks6 less than 6, greater than 5 disks7AAEvaluation by polarimeter (Test Method B) should be used for apparent tempernumbers greater than six.8.2 Exa

29、mination of Square, Oval, and Irregular ShapesMake the polariscopic examination of that container curve orcorner that shows the maximum order of retardation color andrecord the temper number in accordance with the procedureoutlined in 8.1.8.3 Examination of the Container SidewallsMatch themaximum re

30、tardation color observed in the container sidewallwith the maximum retardation color at the calibration point ofthe standard reference disks, and record the apparent tempernumber in accordance with the procedure outlined in 8.1.1.8.4 Examination of Colored WareUsing the polariscopewith the tint plat

31、e in the field of view, rotate the container todetermine the location of the highest order retardation color atthe inside knuckle position. View the bottom of the containerthrough the open container finish and select as a reference areathe darkest appearing area of the container bottom havingminimum

32、 retardation, usually found at the center of thecontainer bottom. Then, with the tint plate in position, hold astandard reference disk under the reference area in the bottomof the container such that the calibration point on the disk isdirectly under the reference area in the center bottom of thecon

33、tainer. Compare the retardation color of the reference areain the container center bottom as modified by the standardreference disk with the maximum retardation color as normallyobserved at the inside knuckle of the container bottom. If thiscolor is greater than the modified color of the reference a

34、rea,use two or more disks and grade the annealing in accordancewith the procedure outlined in 8.1.1.9. Report9.1 Report the temper number (real or apparent) obtainedfor each container.TEST METHOD BDETERMINATION WITHPOLARIMETER10. Apparatus10.1 Polarimeter, conforming to the following require-ments:1

35、0.1.1 The degree of polarization of the field shall be at allpoints not less than 99 %.10.1.2 The field shall be a minimum of 51 mm (2 in.) indiameter greater than the diameter of the container to bemeasured. The distance between the polarizing and analyzingC148 172elements shall be sufficient to al

36、low the container to bepositioned to permit the inside bottle bottom surface to beviewed through the open container finish.10.1.3 A quarterwave plate with an optical retardation of141 6 14 nm shall be inserted between the specimen and theanalyzer with the slow axis aligned with the plane of polariza

37、-tion of the polarimeter. The brightness of the polarized fieldilluminating the sample shall be a minimum of 300 cd/m2.NOTE 3The retardation measurement will be affected by the com-bined effect of the quarterwave-plate deviation from its nominal value of141 nm and by the deviation of the orientation

38、 of the measured stressdirection from its ideal position of 45 to the polarizer axis.A 14-nm deviation of the quarterwave plate and a stress-directiondeviation of 10 will introduce an error not greater than 8 nm.10.1.4 The analyzer shall be mounted so that it can berotated with respect to the polari

39、zer and the quarterwave plateand the angle of rotation determined.10.1.5 The polarimeter/polariscope should be calibrated orverified according to Practices C1426.10.1.6 Samples must be allowed to cool until the entirethickness of the glass is at room temperature.11. Procedure11.1 Examination of Bott

40、om of Cylindrical FlintContainersRotate the analyzer initially so as to have theanalyzer plane of polarization perpendicular to the polarizingplane of polarization. This is the zero position in which thefield of view should be at maximum darkness or extinction.Introduce the container to be evaluated

41、 into the field of viewwith the tint plate in position. Rotate the container to determinethe location of the highest order retardation color at the insideknuckle position. Remove the tint plate. View the insidecontainer bottom through the open container finish.Adarkenedextinction cross will appear i

42、n the container bottom, withlightened areas between the mutually perpendicular, darkenedlegs of the cross. In containers having a low retardation, theextinction cross will appear to be hazy and indistinct. Theextinction cross would appear to be colored magenta ratherthan appear darkened if the tint

43、plate were in position, or if thecontainer were being observed in a sensitive tint plate polari-scope. Rotating the analyzer causes the darkened extinctioncross to separate into two darkened arcs which move outwardin opposite directions toward the inside knuckle of thecontainer, each arc paralleling

44、 the same diameter in thecontainer bottom. As the two arcs move outward, they developa blue-gray color on the concave side and a brownish color onthe convex side of each arc. When determining the retardationat a selected point in a container, rotate the analyzer until theblue-gray color is just disp

45、laced by the brownish color at theselected point of grading. Rotate the container about itslongitudinal axis to confirm that the selected point correspondsto the location of maximum retardation. If another area ofhigher retardation is revealed by the reappearance of theblue-gray color, rotate the an

46、alyzer further to displace theblue-gray color by the brownish color. Convert the angle ofrotation of the analyzer to the apparent temper number asfollows:Apparent Temper Number Analyzer Rotation, A1 0.07.32 7.414.53 14.621.84 21.929.05 29.136.36 36.443.67 43.750.88 50.958.19 58.265.410 65.572.6AOne

47、degree of rotation of the analyzer is equivalent to about 3.14nm opticalretardation when using a tungsten filament white light source having an effectivewavelength of 565 nm. Thus, the equivalent value is taken to be approximately7.26 rotation per disk as used in Test Method A.12. Examination of Squ

48、are, Oval, and Irregular Shapes12.1 Make the examination at the curve or corner thatreveals the most birefringence when examined in accordancewith the procedure given in 11.1.12.2 Examination of Bottle SidewallsInsert the containerin the polarimeter with the longitudinal axis of the container ata 45

49、 angle to the plane of the polarization. No dark extinctioncross should be visible in the field of view. Rather, broad areasof varying extinction, corresponding to areas of lightness anddarkness, will be visible in the sidewall of the container. Rotatethe container until the point of maximum retardation is locatedin the container sidewall, as evidenced by an area of maximumbrightness in the field of view. Rotate the analyzer until adarkened extinction region converges on and displaces thebrightened area in the container sidewall at t