ASTM C1279-05

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.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:C1279–05
Standard Test Method for
Non-Destructive Photoelastic Measurement of Edge and
Surface Stresses in Annealed, Heat-Strengthened, and Fully
1
Tempered Flat Glass
This standard is issued under the fixed designation C1279; 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 (´) indicates an editorial change since the last revision or reapproval.
1. Scope F218 Test Method for Measuring Optical Retardation and
Analyzing Stress in Glass
1.1 This test method covers the determination of edge
2.2 Other Documents:
stresses and surface stresses in annealed, heat-strengthened,
3
Engineering Standards Manual
and fully tempered flat glass products.
4
“Surface and Edge Stress in Tempered Glass”
1.2 This test method is non-destructive.
1.3 This test method uses transmitted light and is, therefore,
3. Terminology
applicable to light-transmitting glasses.
3.1 Definitions:
1.4 The test method is not applicable to chemically-
3.1.1 analyzer—a polarizing element, typically positioned
tempered glass.
between the specimen being evaluated and the viewer.
1.5 Using the procedure described, surface stresses can be
3.1.2 polarizer—an optical assembly that transmits light
measured only on the “tin” side of float glass.
vibrating in a single planar direction, typically positioned
1.6 Surface-stress measuring instruments are designed for a
between a light source and the specimen being evaluated.
specific range of surface index of refraction.
3.1.3 retardation compensator—an optical device, variants
1.7 This standard does not purport to address all of the
of which are used to quantify the optical retardation produced
safety concerns, if any, associated with its use. It is the
in transparent birefringent materials: typically positioned be-
responsibility of the user of this standard to establish appro-
tween the specimen being evaluated and the analyzer.
priate safety and health practices and determine the applica-
3.2 For definition of terms used in this test method, refer to
bility of regulatory limitations prior to use.
Terminology C162.
2. Referenced Documents
4. Summary of Test Methods
2
2.1 ASTM Standards:
2 4.1 Two test methods are described in this standard:
C162 Terminology of Glass and Glass Products
4.1.1 Procedure A describes a test method for measuring
C770 Test Method for Measurement of Glass Stress—
surface stress using light propagating nearly parallel to the
Optical Coefficient
surface.
C1048 SpecificationforHeat-TreatedFlatGlass—KindHS,
4.1.2 Procedure B describes a test method for measuring
Kind FT Coated and Uncoated Glass
edge-stress using light propagating in the direction perpendicu-
E691 Practice for Conducting an Interlaboratory Study to
lar to the surface.
Determine the Precision of a Test Method
4.2 In both methods, the fundamental photoelastic concept
is used. As a result of stresses, the material becomes optically
anisotropic or birefringent. When polarized light propagates
1
This test method is under the jurisdiction of ASTM Committee C14 on Glass
through such anisotropic materials, the differences in the speed
and Glass Products and is the direct responsibility of Subcommittee C14.08 on Flat
of light rays vibrating along the maximum and minimum
Glass.
principal stress introduce a relative retardation between these
Current edition approved April 1, 2005. Published April 2005.
Originally approved in 1994. Last previous edition approved in 2000 as
´1
C1279-00 . DOI: 10.1520/C1279-05.
2 3
For referenced ASTM standards, visit the ASTM website, www.astm.org, or Available from Glass Association of North America (GANA), 2925 SW
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Wanamaker Drive, Ste A, Topeka, Kansas 66614–5321.
4
Standards volume information, refer to the standard’s Document Summary page on Redner, A. S. and Voloshin, A. S., Proceedings of the Ninth International
the ASTM website. Conference on Experimental Mechanics, Denmark, 1990.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
1

---------------------- Page: 1 ----------------------
C1279–05
rays. This relative retardation is proportional to the measured
where:
stresses,andcanbeaccuratelydeterminedusingcompensators.
R = is the relative retardation,
For additional background see “Surface and Edge Stress in
C = stress-optical constant (see Note 2),
4
Tempered Glass” . S = surface stress in the direction perpendicular to the
path, t
t = path of light traveling between the entrance and exit
5. Significance and Use
points 1, 2 (Fig. 1),
5.1 The strength and performance of heat-strengthened and
a = Geometrical fa
...