ASTM C148-00

Standard Test Methods for Polariscopic Examination of Glass Containers

SCOPE
1.1 These test methods describe the determination of relative optical retardation associated with the state of anneal of glass containers. Two alternative test methods are covered as follows:  Sections Test Method-A Comparison with Reference 6 to 9 Standards Using a Polariscope Test Method-B Determination with 10 to 12 Polarimeter
1.2 Test Method A is useful in determining retardations less than 150 nm, while Test Method B is useful in determining retardations less than 565 nm. Note 1-The apparent temper number as determined by these test methods depends primarily on ( ) the magnitude and distribution of the residual stress in the glass, ( ) the thickness of the glass (optical path length at the point of grading), and ( ) the composition of the glass. For all usual soda-lime silica bottle glass compositions, the effect of the composition is negligible. In an examination of the bottom of a container, the thickness of glass may be taken into account by use of the following formula, which defines a real temper number, R , in terms of the apparent temper number, A , and the bottom thickness, : R  = A  (0.160/ ) where is in inches, or R  = A  (4.06/ ) where is in millimeters. This thickness should be measured at the location of the maximum apparent retardation. Interpretation of either real or apparent temper number requires practical 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 address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

General Information

• Status: Historical
• Publication Date: 09-Apr-2000
• ICS: 81.040.30 - Glass products
• Technical Committee: C14 - Glass and Glass Products
• Drafting Committee: C14.07 - Glass Containers

Relations

• Replaced By: ASTM C148-00(2006) - Standard Test Methods for Polariscopic Examination of Glass Containers
• Effective Date: 01-Apr-2006
• Referred By: ASTM C158-02(2017) - Standard Test Methods for Strength of Glass by Flexure (Determination of Modulus of Rupture)
• Effective Date: 10-Apr-2000
• Referred By: ASTM C1426-14(2020) - Standard Practices for Verification and Calibration of Polarimeters
• Effective Date: 10-Apr-2000
• Referred By: ASTM E890-94(2021) - Standard Specification for Disposable Glass Culture Tubes
• Effective Date: 10-Apr-2000
• Referred By: ASTM C162-05(2015) - Standard Terminology of<brk type="line"/> Glass and Glass Products
• Effective Date: 10-Apr-2000
• Referred By: ASTM F2179-20 - Standard Specification for Annealed Soda-Lime-Silicate Glass Containers That Are Produced for Use as Candle Containers
• Effective Date: 10-Apr-2000

Standards Content (Sample)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation:C148–00
Standard Test Methods for
Polariscopic Examination of Glass Containers
This standard is issued under the fixed designation C 148; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (e) 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. Scope 2. Referenced Documents
1.1 These test methods describe the determination of rela- 2.1 ASTM Standards:
tive optical retardation associated with the state of anneal of C 162 Terminology of Glass and Glass Products
glass containers. Two alternative test methods are covered as C 224 Practice for Sampling Glass Containers
follows: C 1426 Practices for Verification and Calibration of Pola-
rimeters
Sections
Test Method A—Comparison with Reference 6to9
3. Terminology
Standards Using a Polariscope
3.1 Definitions— For definitions of terms used in these test
Test Method B—Determination with Polarimeter 10 to 12
methods see Terminology C 162.
1.2 Test MethodAis useful in determining retardations less
than 150 nm, while Test Method B is useful in determining
4. Significance and Use
retardations less than 565 nm.
4.1 These two test methods are provided for evaluating the
NOTE 1—The apparent temper number as determined by these test quality of annealing. These test methods can be used in the
methods depends primarily on (1) the magnitude and distribution of the
quality control of glass containers or other products made of
residual stress in the glass, (2) the thickness of the glass (optical path
similarglasscompositions,wherethedegreeofannealingmust
length at the point of grading), and ( 3) the composition of the glass. For
be verified to ensure quality products. These test methods
all usual soda-lime silica bottle glass compositions, the effect of the
apply to glass containers manufactured from commercial
composition is negligible. In an examination of the bottom of a container,
soda-lime-silica glass compositions.
the thickness of glass may be taken into account by use of the following
formula, which defines a real temper number, T , in terms of the apparent
R
5. Sampling
temper number, T , and the bottom thickness, t:
A
T = T (0.160/t)
R A 5.1 Methods of sampling a minimum lot from a group of
where t is in inches, or
containers of a given type are given in Practice C 224 for the
T = T (4.06/t)
R A
various situations to which that method may apply.
where t is in millimetres.
This thickness should be measured at the location of the maximum
TEST METHOD A—COMPARISON WITH
apparent retardation. Interpretation of either real or apparent temper
REFERENCE STANDARDS USING A POLARISCOPE
number requires practical experience with the particular ware being
evaluated.
6. Apparatus
1.3 The values stated in SI units are to be regarded as the
6.1 Polariscope, conforming to the following requirements:
standard. The values given in parentheses are for information
6.1.1 The degree of polarization of the field at all points
only.
shall not be less than 99 %.
1.4 This standard does not purport to address all of the
6.1.2 The field shall be a minimum of 51 mm (2 in.) in
safety concerns, if any, associated with its use. It is the
diameter greater than the diameter of the container to be
responsibility of the user of this standard to establish appro-
measured. The distance between the polarizing and analyzing
priate safety and health practices and determine the applica-
elements shall be sufficient to allow the inside bottle bottom
bility of regulatory limitations prior to use.
surface 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 of
These test methods are under the jurisdiction of ASTM Committee C14 on
less than 5 nm and with its slow axis at 45° to the plane of
Glass and Glass Products and are the direct responsibility of Subcommittee C14.07
on Glass Containers.
Current edition approved April 10, 2000. Published May 2000. Originally
published as C 148 – 39 T. Last previous edition C 148 – 95. Annual Book of ASTM Standards, Vol 15.02.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
C148–00
polarization, shall be used. Such an orientation will produce a corner that shows the maximum order of retardation color and
magenta background in the field of view. The brightness of the record the temper number in accordance with the procedure
polarized field illuminating the sample shall be a minimum of outlined in 8.1.
300 cd/m . 8.3 Examination of the Container Sidewalls—Match the
maximum retardation color observed in the container sidewall
NOTE 2—Color discrimination remains satisfactory with retardations
with the maximum retardation color at the calibration point of
between 510 and 580 nm, but optimum conditions are attained at 565 nm.
the standard reference disks, and record the apparent temper
7. Calibration and Standardization
number in accordance with the procedure outlined in 8.1.1.
8.4 Examination of Colored Ware—Using the polariscope
7.1 A set of not less than five standardized glass disks of
with the tint plate in the field of view, rotate the container to
known retardation stress shall be used to cover the range of
determine the location of the highest order retardation color at
commercial container annealing. Such disks shall be circular
the inside knuckle position. View the bottom of the container
plates of glass not less than 76 mm (3 in.) nor more than 102
through the open container finish and select as a reference area
mm (4 in.) in diameter. Each disk shall have a nominal
the darkest appearing area of the container bottom having
retardation at the calibration point, 6.4 mm (0.25 in.) from the
minimum retardation, usually found at the center of the
outer circumference of the disk, corresponding to not less than
container bottom. Then, with the tint plate in position, hold a
21.8 nm nor more than 23.8 nm of optical retardation.
standard reference disk under the reference area in the bottom
of the container such that the calibration point on the disk is
8. Procedure
directly under the reference area in the center bottom of the
8.1 Examination of the Bottom of Cylindrical Flint
container. Compare the retardation color of the reference area
Containers—View the inside bottom of the container through
in the container center bottom as modified by the standard
the open container finish. Rotate the container to determine the
reference disk with the maximum retardation color as normally
location of the highest order of retardation color at the inside
observed at the inside knuckle of the container bottom. If this
knuckle position. Compare the highest order retardation color
color is greater than the modified color of the reference area,
observed at the bottom of the container to the retardation color
use two or more disks and grade the annealing in accordance
seen at the calibration point in various numbers of the standard
with the procedure outlined in 8.1.1.
disks stacked one on top of the other and held parallel to the
surface of the polarizer. Determine whether the maximum
9. Report
order of retardation color in the container bottom is less than
9.1 Report the temper number (real or apparent) obtained
that in one disk, less than that in two and greater than one, less
for each container.
than that in three and greater than two, and so forth. It is
seldom possible to obtain an exact match of the order of
TEST METHOD B—DETERMINATION WITH
retardation color scheme in the container with the reference
POLARIMETER
standards. Accordingly, record the temper number of the
container using the following procedure:
10. Apparatus
8.1.1 Temper Number Determination—When a maximum
10.1 Polarimeter, conforming to the following require-
order retardation color observed in the container bottom is
ments:
greater than that of N disks but less than N + 1 disks, the
10.1.1 The degree of polarization of the field shall be at all
apparent temper grade is judged to be tha
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