1、Designation: C148 12Standard 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 Department of Defense.1. Scope1.1 These test methods describe the determination of rela-tive o
3、ptical retardation associated with the state of anneal ofglass containers. Two alternative test methods are covered asfollows:SectionsTest Method AComparison with ReferenceStandards Using a Polariscope6 to 9Test Method BDetermination with Polarimeter 10 to 121.2 Test Method A is useful in determinin
4、g retardations 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 (op
5、tical 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 followi
6、ngformula, which defines a real temper number, TR, in terms of the apparenttemper number, TA, and the bottom thickness, t:TR= TA(0.160/t)where t is in inches, orTR= TA(4.06/t)where t is in millimetres.This thickness should be measured at the location of the maximumapparent retardation. Interpretatio
7、n of either real or apparent tempernumber requires practical experience with the particular ware beingevaluated.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 thesafety
8、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.2. Referenced Documents2.1 ASTM Standards:2C162 Terminology of Glass and Glass
9、 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 provided for evaluating the
10、quality 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 manufactured from commercialsoda-l
11、ime-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. Apparatus6.1 Polariscope,
12、 conforming to the following requirements:6.1.1 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 (2 in.) indiameter greater than the diameter of the container to bemeasured. The distance between the polarizing and analyzinge
13、lements 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 retar-dation of 565 nm, with a variation across the field of view of1These test methods are under the jurisdiction of ASTM Commit
14、tee C14 onGlass and Glass Products and are the direct responsibility of Subcommittee C14.07on Glass Containers.Current edition approved April 1, 2012. Published April 2012. Originallyapproved in 1939. Last previous edition approved in 2011 as C148 00 (2011).DOI: 10.1520/C0148-12.2For referenced ASTM
15、 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 Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohoc
16、ken, PA 19428-2959, United States.less 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 minimum of300 cd/m2.NOTE 2Color
17、 discrimination remains satisfactory with retardationsbetween 510 and 580 nm, but optimum conditions are attained at 565 nm.7. Calibration and Standardization7.1 A set of not less than five standardized glass disks ofknown retardation stress shall be used to cover the range ofcommercial container an
18、nealing. 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 at 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
19、 23.8 nm of optical retardation.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 thelocation of the highest order of retardation color at the insideknuckle position. Com
20、pare 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 held parallel to thesurface of the polarizer. Determine whether the maximumorder of retard
21、ation 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 match of the order ofretardation color scheme in the container with the referencestandards.
22、 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 N disks but less than N + 1 disks, theapparent temper grade is judged to be that of N +
23、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 less than 1 disk2 less than 2, greater than 1 disk3 less than 3, greater than 2 disks4 le
24、ss than 4, greater than 3 disks5 less than 5, greater than 4 disks6 less than 6, greater than 5 disks7A_AEvaluation by polarimeter (Test Method B) should be used for apparent tempernumbers greater than six.8.2 Examination of Square, Oval, and Irregular ShapesMake the polariscopic examination of that
25、 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 retardation color observed in the container sidewallwith the maximum retardation color at
26、 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 plate in the field of view, rotate the container todetermine the location of the highest or
27、der 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 retardation, usually found at the center of thecontainer bottom. Then, with the tint p
28、late 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 thecontainer. Compare the retardation color of the reference areain the container center bott
29、om 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 area,use two or more disks and grade the annealing in accordancewith the procedure outli
30、ned 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:10.1.1 The degree of polarization of the field shall be at allpoints not less than 99 %.
31、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 analyzingelements shall be sufficient to allow the container to bepositioned to permit the inside bottle bottom surface to beviewed throug
32、h 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-tion of the polarimeter. The brightness of the polarized fieldilluminating the sample shall be
33、 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 of the measured stressdirection from its ideal position of 45 to the polarizer axis.A 14-nm de
34、viation 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 polarizer and the quarterwave plateand the angle of rotation determined.10.1.5 The polarimeter/polari
35、scope should be calibrated orverified according to Practices C1426.11. Procedure11.1 Examination of Bottom of Cylindrical FlintContainersRotate the analyzer initially so as to have theC148 122analyzer plane of polarization perpendicular to the polarizingplane of polarization. This is the zero positi
36、on in which thefield of view should be at maximum darkness or extinction.Introduce the container to be evaluated 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
37、plate. View the insidecontainer bottom through the open container finish.Adarkenedextinction cross will appear in 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 haz
38、y and indistinct. Theextinction cross would appear to be colored magenta ratherthan appear darkened if the tint 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 darken
39、ed arcs which move outwardin opposite directions toward the inside knuckle of the con-tainer, each arc paralleling the same diameter in the containerbottom. As the two arcs move outward, they develop ablue-gray color on the concave side and a brownish color onthe convex side of each arc. When determ
40、ining the retardationat a selected point in a container, rotate the analyzer until theblue-gray color is just displaced 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 reta
41、rdation. If another area ofhigher retardation is revealed by the reappearance of theblue-gray color, rotate the analyzer 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
42、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 65.572.6_AOne 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
43、equivalent value is taken to be approximately7.26 rotation per disk as used in Test Method A.12. Examination of Square, 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 Exami
44、nation of Bottle SidewallsInsert the containerin the polarimeter with the longitudinal axis of the container ata 45 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 an
45、ddarkness, 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 displ
46、aces thebrightened area in the container sidewall at the selected pointof grading. Convert the degrees of rotation of the analyzer to anapparent temper number in accordance with the tabulations in11.1.12.3 Examination of Colored WareUse the same proce-dure as in flint ware. The point of extinction i
47、s usually moredifficult to determine in colored ware because of the absence ofthe blue-gray and brownish colors, as well as the reduced lightintensity caused by preferential absorption of light in thecolored ware. First, rotate the analyzer until the darkened crossseparates and the darkened area jus
48、t extinguishes the lightenedarea of the selected point of grading. Record the degrees ofrotation. Then continue rotating the analyzer in the samedirection until well past the extinction point. Now reverse therotation of the analyzer and redetermine the extinction point byjust making the lightened ar
49、ea reappear. Record the degree ofrotation. Average the degrees of rotation achieved in bothmeasurements.13. Report13.1 Report the temper number (real or apparent) or ana-lyzer rotation obtained for each container examined.14. Precision and Bias14.1 PrecisionThe precision of both of these test methodshas been determined by round-robin testing to be within onestandard temper disk.14.2 BiasThe bias of these test methods cannot be estab-lished in that the test methods contained herein are comparativeand yield a result rel
