1、Designation: C148 12C148 14Standard 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
2、 number 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
3、 relative optical retardation associated with the state of anneal of glasscontainers. Two alternative test methods are covered as follows:SectionsTest Method AComparison with ReferenceStandards Using a Polariscope6 to 9Test Method BDetermination with Polarimeter 10 to 121.2 Test Method A is useful i
4、n determining retardations less than 150 nm, while Test Method B is useful in determiningretardations less than 565 nm.NOTE 1The apparent temper number as determined by these test methods depends primarily on (1) the magnitude and distribution of the residualstress in the glass, (2) the thickness of
5、 the glass (optical path length at the point of grading), and (3) the composition of the glass. For all usual soda-limesilica bottle glass compositions, the effect of the composition is negligible. In an examination of the bottom of a container, the thickness of glass maybe taken into account by use
6、 of the following formula, which defines a real temper number, TR, in terms of the apparent temper number, TA, and the bottomthickness, 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 maximum apparent retar
7、dation. Interpretation of either real or apparent temper number requirespractical experience with the particular ware being evaluated.1.3 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.1.4 This standard does not purport to a
8、ddress all of the safety concerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatorylimitations prior to use.2. Referenced Documents2.1 ASTM Standards:2C162 Terminol
9、ogy of Glass and Glass ProductsC224 Practice for Sampling Glass ContainersC1426 Practices for Verification and Calibration of Polarimeters3. Terminology3.1 Definitions For definitions of terms used in these test methods see Terminology C162.4. Significance and Use4.1 These two test methods are provi
10、ded for evaluating the quality of annealing. These test methods can be used in the qualitycontrol of glass containers or other products made of similar glass compositions, where the degree of annealing must be verifiedto ensure quality products. These test methods apply to glass containers manufactu
11、red from commercial soda-lime-silica glasscompositions.1 These test methods are under the jurisdiction of ASTM Committee C14 on Glass and Glass Products and are the direct responsibility of Subcommittee C14.07 on GlassContainers.Current edition approved April 1, 2012May 1, 2014. Published April 2012
12、May 2014. Originally approved in 1939. Last previous edition approved in 20112012 asC148 00C148 12. (2011). DOI: 10.1520/C0148-12.10.1520/C0148-14.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standard
13、svolume information, refer to the standards Document Summary page on the ASTM website.This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may not be technically possible to
14、adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Consh
15、ohocken, PA 19428-2959. United States15. Sampling5.1 Methods of sampling a minimum lot from a group of containers of a given type are given in Practice C224 for the varioussituations to which that method may apply.TEST METHOD ACOMPARISON WITH REFERENCE STANDARDS USING A POLARISCOPE6. Apparatus6.1 Po
16、lariscope, conforming to the following requirements:6.1.1 The degree of polarization of the field at all points shall not be less than 99 %.6.1.2 The field shall be a minimum of 51 mm (2 in.) in diameter greater than the diameter of the container to be measured. Thedistance between the polarizing an
17、d analyzing elements shall be sufficient to allow the inside bottle bottom surface to be viewedthrough the open container finish.6.1.3 Asensitive tint plate, having a nominal optical retardation of 565 nm, with a variation across the field of view of less than5 nm and with its slow axis at 45 to the
18、 plane of polarization, shall be used. Such an orientation will produce a magentabackground in the field of view. The brightness of the polarized field illuminating the sample shall be a minimum of 300 cd/m2.NOTE 2Color discrimination remains satisfactory with retardations between 510 and 580 nm, bu
19、t optimum conditions are attained at 565 nm.7. Calibration and Standardization7.1 Aset of not less than five standardized glass disks of known retardation stress shall be used to cover the range of commercialcontainer annealing. Such disks shall be circular plates of glass not less than 76 mm (3 in.
20、) nor more than 102 mm (4 in.) indiameter. Each disk shall have a nominal retardation at the calibration point, 6.4 mm (0.25 in.) from the outer circumference ofthe disk, corresponding to not less than 21.8 nm nor more than 23.8 nm of optical retardation. Each disk shall have a nominalretardation at
21、 the calibration point, 6.4 mm (0.25 in.) from the PHYSICAL EDGE of the GLASS disk, corresponding to not lessthan 21.8 nm nor more than 23.8 nm of optical retardation. If the disk is mounted in a frame that covers the glass edge, refer tothe instructions provided by the supplier of the strain disk s
22、et with regard to the distance to the calibration point from the frameID. If unknown, the disks may be removed from the frame, the calibration point marked accordingly, and the disks placed backinto their frames.8. Procedure8.1 Examination of the Bottom of Cylindrical Flint ContainersView the inside
23、 bottom of the container through the opencontainer finish. Rotate the container to determine the location of the highest order of retardation color at the inside knuckleposition. Compare the highest order retardation color observed at the bottom of the container to the retardation color seen at thec
24、alibration point in various numbers of the standard disks stacked one on top of the other and held parallel to the surface of thepolarizer. Determine whether the maximum order of retardation color in the container bottom is less than that in one disk, less thanthat in two and greater than one, less
25、than that in three and greater than two, and so forth. It is seldom possible to obtain an exactmatch of the order of retardation color scheme in the container with the reference standards. Accordingly, record the tempernumber of the container using the following procedure:8.1.1 Temper Number Determi
26、nationWhen a maximum order retardation color observed in the container bottom is greaterthan that of N disks but less than N + 1 disks, the apparent temper grade is judged to be that of N + 1 disks. The apparent tempernumber is always determined to be the next integral temper number greater in value
27、 than the actual observed value as seen in thefollowing table:Apparent Temper Number Observed Temper1 less 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 disks7 A_AEva
28、luation by polarimeter (Test Method B) should be used for apparent temper numbers greater than six.8.2 Examination of Square, Oval, and Irregular ShapesMake the polariscopic examination of that container curve or cornerthat shows the maximum order of retardation color and record the temper number in
29、 accordance with the procedure outlined in8.1.8.3 Examination of the Container SidewallsMatch the maximum retardation color observed in the container sidewall with themaximum retardation color at the calibration point of the standard reference disks, and record the apparent temper number inaccordanc
30、e with the procedure outlined in 8.1.1.C148 1428.4 Examination of Colored WareUsing the polariscope with the tint plate in the field of view, rotate the container to determinethe location of the highest order retardation color at the inside knuckle position. View the bottom of the container through
31、the opencontainer finish and select as a reference area the darkest appearing area of the container bottom having minimum retardation,usually found at the center of the container bottom. Then, with the tint plate in position, hold a standard reference disk under thereference area in the bottom of th
32、e container such that the calibration point on the disk is directly under the reference area in thecenter bottom of the container. Compare the retardation color of the reference area in the container center bottom as modified bythe standard reference disk with the maximum retardation color as normal
33、ly observed at the inside knuckle of the container bottom.If this color is greater than the modified color of the reference area, 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) obtained for each
34、 container.TEST METHOD BDETERMINATION WITH POLARIMETER10. Apparatus10.1 Polarimeter, conforming to the following requirements:10.1.1 The degree of polarization of the field shall be at all points not less than 99 %.10.1.2 The field shall be a minimum of 51 mm (2 in.) in diameter greater than the dia
35、meter of the container to be measured.The distance between the polarizing and analyzing elements shall be sufficient to allow the container to be positioned to permitthe inside bottle bottom surface to be viewed through the open container finish.10.1.3 Aquarterwave plate with an optical retardation
36、of 141 6 14 nm shall be inserted between the specimen and the analyzerwith the slow axis aligned with the plane of polarization of the polarimeter. The brightness of the polarized field illuminating thesample shall be a minimum of 300 cd/m2.NOTE 3The retardation measurement will be affected by the c
37、ombined effect of the quarterwave-plate deviation from its nominal value of 141 nmand by the deviation of the orientation of the measured stress direction from its ideal position of 45 to the polarizer axis.A 14-nm deviation of the quarterwave plate and a stress-direction deviation of 10 will introd
38、uce an error not greater than 8 nm.10.1.4 The analyzer shall be mounted so that it can be rotated with respect to the polarizer and the quarterwave plate and theangle of rotation determined.10.1.5 The polarimeter/polariscope should be calibrated or verified according to Practices C1426.11. Procedure
39、11.1 Examination of Bottom of Cylindrical Flint ContainersRotate the analyzer initially so as to have the analyzer plane ofpolarization perpendicular to the polarizing plane of polarization. This is the zero position in which the field of view should beat maximum darkness or extinction. Introduce th
40、e container to be evaluated into the field of view with the tint plate in position.Rotate the container to determine the location of the highest order retardation color at the inside knuckle position. Remove the tintplate. View the inside container bottom through the open container finish.Adarkened
41、extinction cross will appear in the containerbottom, with lightened areas between the mutually perpendicular, darkened legs of the cross. In containers having a lowretardation, the extinction cross will appear to be hazy and indistinct. The extinction cross would appear to be colored magentarather t
42、han appear darkened if the tint plate were in position, or if the container were being observed in a sensitive tint platepolariscope. Rotating the analyzer causes the darkened extinction cross to separate into two darkened arcs which move outwardin opposite directions toward the inside knuckle of th
43、e container, each arc paralleling the same diameter in the container bottom.As the two arcs move outward, they develop a blue-gray color on the concave side and a brownish color on the convex side ofeach arc. When determining the retardation at a selected point in a container, rotate the analyzer un
44、til the blue-gray color is justdisplaced by the brownish color at the selected point of grading. Rotate the container about its longitudinal axis to confirm thatthe selected point corresponds to the location of maximum retardation. If another area of higher retardation is revealed by thereappearance
45、 of the blue-gray color, rotate the analyzer further to displace the blue-gray color by the brownish color. Convert theangle of rotation of the analyzer to the apparent temper number as follows:Apparent Temper Number Analyzer Rotation, A1 0.07.32 7.414.53 14.621.84 21.929.05 29.136.36 36.443.67 43.7
46、50.88 50.958.19 58.265.410 65.572.6_C148 143AOne degree of rotation of the analyzer is equivalent to about 3.14nm optical retardation when using a tungsten filament white light source having an effective wavelengthof 565 nm. Thus, the equivalent value is taken to be approximately 7.26 rotation per d
47、isk as used in Test Method A.C148 14412. Examination of Square, Oval, and Irregular Shapes12.1 Make the examination at the curve or corner that reveals the most birefringence when examined in accordance with theprocedure given in 11.1.12.2 Examination of Bottle SidewallsInsert the container in the p
48、olarimeter with the longitudinal axis of the container at a 45angle to the plane of the polarization. No dark extinction cross should be visible in the field of view. Rather, broad areas of varyingextinction, corresponding to areas of lightness and darkness, will be visible in the sidewall of the co
49、ntainer. Rotate the containeruntil the point of maximum retardation is located in the container sidewall, as evidenced by an area of maximum brightness in thefield of view. Rotate the analyzer until a darkened extinction region converges on and displaces the brightened area in the containersidewall at the selected point of grading. Convert the degrees of rotation of the analyzer to an apparent temper number inaccordance with the tabulations in 11.1.12.3 Examination of Colored WareUse the same procedure as in fli
