ASTM C1376-21a

Standard Specification for Pyrolytic and Vacuum Deposition Coatings on Flat Glass

ABSTRACT
This specification covers the optical and aesthetic quality requirements for coatings applied to glass for use in building glazing. The coatings covered are applied to the glass using either pyrolytic or vacuum (sputtering) deposition methods and are typically applied to control solar heat gain, energy performance, comfort level, and condensation and enhance the aesthetic of the building. This specification groups coated glass according to application. These groups are: vision, spandrel/nonvision, and overhead. Coated flat glass furnished under this specification shall be of the following kinds: Kind CV; Kind CO; and Kind CS.
SCOPE
1.1 This specification covers the optical and aesthetic quality requirements for pyrolytic and vacuum deposition coatings applied on flat glass for use in building glazing.  
1.2 The coatings are applied on the glass using either pyrolytic or vacuum sputtering deposition methods to control solar heat gain, energy performance, comfort level, and condensation and to enhance the aesthetic of the building.  
1.3 This specification addresses blemishes related to the coating only. It does not address glass blemishes, applied ceramic frits to spandrel glass, and organic film opacifiers.  
1.4 The Nonuniformity for Coated Glass requirements, given in 6.10, pertain to glazing units of vertical and sloped orientations as installed in the building exterior.  
1.5 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical conversions to SI units that are provided for information only and are not considered standard.  
1.6 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

General Information

• Status: Published
• Publication Date: 31-Aug-2021
• ICS: 81.040.20 - Glass in building
• Technical Committee: C14 - Glass and Glass Products
• Drafting Committee: C14.08 - Flat Glass

Relations

• Refers: ASTM C162-23 - Standard Terminology of Glass and Glass Products
• Effective Date: 01-Oct-2023
• Refers: ASTM C1048-18 - Standard Specification for Heat-Strengthened and Fully Tempered Flat Glass
• Effective Date: 01-Oct-2018
• Refers: ASTM C162-05(2015) - Standard Terminology of<brk type="line"/> Glass and Glass Products
• Effective Date: 01-Nov-2015
• Refers: ASTM D2244-15a - Standard Practice for Calculation of Color Tolerances and Color Differences from Instrumentally Measured Color Coordinates
• Effective Date: 01-Aug-2015
• Refers: ASTM D2244-15e1 - Standard Practice for Calculation of Color Tolerances and Color Differences from Instrumentally Measured Color Coordinates
• Effective Date: 01-Jan-2015
• Refers: ASTM D2244-15 - Standard Practice for Calculation of Color Tolerances and Color Differences from Instrumentally Measured Color Coordinates
• Effective Date: 01-Jan-2015
• Refers: ASTM D2244-14 - Standard Practice for Calculation of Color Tolerances and Color Differences from Instrumentally Measured Color Coordinates
• Effective Date: 01-May-2014
• Refers: ASTM C1048-12 - Standard Specification for Heat-Strengthened and Fully Tempered Flat Glass
• Effective Date: 15-Mar-2012
• Refers: ASTM C1048-12e1 - Standard Specification for Heat-Strengthened and Fully Tempered Flat Glass
• Effective Date: 15-Mar-2012
• Refers: ASTM C1036-11e1 - Standard Specification for Flat Glass
• Effective Date: 01-Oct-2011
• Refers: ASTM C1036-11 - Standard Specification for Flat Glass
• Effective Date: 01-Oct-2011
• Refers: ASTM D2244-11 - Standard Practice for Calculation of Color Tolerances and Color Differences from Instrumentally Measured Color Coordinates
• Effective Date: 01-Jun-2011
• Refers: ASTM D2244-09a - Standard Practice for Calculation of Color Tolerances and Color Differences from Instrumentally Measured Color Coordinates
• Effective Date: 01-Aug-2009
• Refers: ASTM D2244-09 - Standard Practice for Calculation of Color Tolerances and Color Differences from Instrumentally Measured Color Coordinates
• Effective Date: 01-Jul-2009
• Refers: ASTM D2244-07 - Standard Practice for Calculation of Color Tolerances and Color Differences from Instrumentally Measured Color Coordinates
• Effective Date: 01-May-2007

Overview

ASTM C1376-21a is the internationally recognized standard specification for pyrolytic and vacuum deposition coatings on flat glass, published by ASTM International. This standard sets comprehensive optical and aesthetic quality requirements for glass coatings used in building glazing. It applies to coatings applied by two principal methods: pyrolytic deposition and vacuum (sputtering) deposition. These coatings are essential for enhancing the performance and visual appeal of glass used in commercial and residential buildings, with typical applications including solar heat gain control, improved energy efficiency, increased occupant comfort, condensation management, and design aesthetics.

Key Topics

ASTM C1376-21a standard covers:

• Types of Coated Glass: The document categorizes coated flat glass into three main groups based on their intended application:
  • Vision glass (Kind CV)
  • Overhead glass (Kind CO)
  • Spandrel/non-vision glass (Kind CS)
• Coating Processes:
  • Pyrolytic coating - applied to hot glass during manufacturing
  • Vacuum deposition (sputtering) - applied to flat glass sheets in a vacuum chamber
• Inspection and Quality Requirements:
  • Assessment of optical and aesthetic properties, specifically coating blemishes
  • Inspection protocols, viewing distances, and lighting conditions
  • Clearly defined limits on acceptable blemish size, type, and location
• Blemish Types:
  • Scratches, rubs, pinholes, spots, crazing, contaminants, corrosion, color nonuniformity
• Nonuniformity and Color Variation:
  • Guidelines for measuring and evaluating color differences between glass lites
  • Use of spectrophotometers and color measurement criteria (e.g., ΔE*ab as defined in ASTM D2244)

Applications

The practical value of ASTM C1376-21a is significant for anyone sourcing, specifying, or working with flat glass in architectural projects:

• Commercial Buildings: Ensures consistent quality in high-rise curtain walls, storefronts, and office towers using coated vision or spandrel glass.
• Residential Construction: Used for energy-efficient windows and patio doors, where control of thermal gain and uniform appearance are critical.
• Public and Institutional Projects: Helps specify glass quality for schools, hospitals, and government buildings, addressing both performance and aesthetics.
• Roofing and Overhead Glazing: Defines requirements for glass used in skylights and canopy installations to mitigate visible blemishes and ensure safety.
• Energy Performance: Supports energy codes and green building requirements by enabling reliable use of coated glass to reduce heat ingress and improve occupant comfort.
• Design Consistency: Minimizes undesirable visual differences in glass appearance, supporting architects’ intent and owner satisfaction.
• Manufacturers & Glaziers: Guarantees transparent criteria for defect inspection, acceptance, and quality control processes.

Related Standards

Understanding ASTM C1376-21a is enhanced by familiarity with related ASTM standards and terminology, such as:

• ASTM C1036: Standard Specification for Flat Glass
• ASTM C1048: Specification for Heat-Strengthened and Fully Tempered Flat Glass
• ASTM C162: Terminology of Glass and Glass Products
• ASTM D2244: Practice for Calculation of Color Tolerances and Color Differences from Instrumentally Measured Color Coordinates

These references further ensure accurate material specification and performance expectations in building projects involving architectural glass.

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Keywords: ASTM C1376-21a, flat glass coatings, pyrolytic coating, vacuum deposition, sputtered coatings, architectural glass, optical quality, aesthetic requirements, color uniformity, building glazing standards.

Standards Content (Sample)

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation:C1376 −21a
Standard Specification for
Pyrolytic and Vacuum Deposition Coatings on Flat Glass
This standard is issued under the fixed designation C1376; 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 C1048 Specification for Heat-Strengthened and Fully Tem-
pered Flat Glass
1.1 This specification covers the optical and aesthetic qual-
D2244 Practice for Calculation of Color Tolerances and
ity requirements for pyrolytic and vacuum deposition coatings
Color Differences from Instrumentally Measured Color
applied on flat glass for use in building glazing.
Coordinates
1.2 The coatings are applied on the glass using either
pyrolytic or vacuum sputtering deposition methods to control
3. Terminology
solar heat gain, energy performance, comfort level, and con-
3.1 Definitions:
densation and to enhance the aesthetic of the building.
3.1.1 Refer to Terminology C162 or Specification C1036 or
1.3 This specification addresses blemishes related to the
C1048, as appropriate.
coating only. It does not address glass blemishes, applied
3.1.2 blemishes in flat glass—refer to Specification C1036
ceramic frits to spandrel glass, and organic film opacifiers.
or C1048, as appropriate.
1.4 The Nonuniformity for Coated Glass requirements,
3.1.3 These definitions do not apply to in-service damage.
given in 6.10, pertain to glazing units of vertical and sloped
3.2 Definitions of Terms Specific to This Standard:
orientations as installed in the building exterior.
3.2.1 coated overhead glass—glassusedinaninstallationin
1.5 The values stated in inch-pound units are to be regarded
which the lower edge of the glass is more than 6 ft (1.8 m)
as standard. The values given in parentheses are mathematical
above(theviewer’s)floorlevelorcannotbeapproachedwithin
conversions to SI units that are provided for information only
10 ft (3.0 m); the glass can usually but not always be viewed
and are not considered standard.
in both transmission and reflection; the glass is usually sloping
1.6 This international standard was developed in accor-
in from the vertical plane, however, may also be vertical or
dance with internationally recognized principles on standard-
sloping out from the vertical plane.
ization established in the Decision on Principles for the
3.2.2 coated spandrel/non-vision glass—glass used in an
Development of International Standards, Guides and Recom-
installation in which the glass is only viewed in reflection from
mendations issued by the World Trade Organization Technical
the building’s exterior; the glass is usually installed vertically,
Barriers to Trade (TBT) Committee.
however, may be at a slope to the vertical plane.
2. Referenced Documents
3.2.3 coated vision glass—glass used in an installation in
which the lower edge of the glass is a maximum of 6 ft (1.8 m)
2.1 Reference to these documents shall be the latest issue
above (the viewer’s) floor level; the glass can be viewed in
unless otherwise specified by the authority applying this
transmission or reflection; the glass is usually vertical,
specification.
however, may also be sloping in or out from the vertical plane;
2.2 ASTM Standards:
and the glass can be approached within 10 ft (3.0 m) or less. If
C162 Terminology of Glass and Glass Products
the distance is greater than 10 ft (3.0 m), see coated overhead
C1036 Specification for Flat Glass
glass, which would apply.
3.2.4 coating rub—a surface abrasion of appreciable width
This specification is under the jurisdiction of ASTM Committee C14 on Glass
that has partial or complete removal of the coating producing
and Glass Products and is the direct responsibility of Subcommittee C14.08 on Flat
a hazy appearance.
Glass.
Current edition approved Sept. 1, 2021. Published November 2021. Originally
3.2.5 coating scratch—partial or complete removal of the
approved in 1997. Last previous edition approved in 2021 as C1376 – 21. DOI:
coating along a thin straight or curved line.
10.1520/C1376-21A.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
3.2.6 corrosion—change in the color or level of reflected or
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
transmitted light over all or part of the glass surface as a result
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. of degradation of the coating from external sources.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
C1376−21a
3.2.7 crazing—a random conglomeration of fine lines or 5. Classification
cracks in the coating.
5.1 Kinds—Pyrolytic or vacuum deposition coated flat glass
3.2.8 cut size—flat glass cut to specific dimensions for end furnished under this specification shall be of the following
use.
kinds, as specified:
5.1.1 Kind CV—Flat transparent glass conforming to the
3.2.9 edge deletion—the process of removing a portion of
applicable requirements of Specification C1036 or C1048,or
the vacuum deposition coating from the glass surface typically
both, and having a coating applied to one or more of the glass
within 1 in. (25 mm) or less of all edges before insulating or
surfaces which further conforms with the requirements here-
laminating the glass.
inafter specified for coated vision glass.
3.2.10 mark/contaminant—a deposit of foreign material on
5.1.2 Kind CO—Flat transparent glass conforming to the
the surface of the glass or coating.
applicable requirements of Specification C1036 or C1048,or
3.2.11 nonuniformity—obvious variation in color within a
both, and having a coating applied to one or more of the glass
lite of coated glass, or between two or more lites of coated
surfaces which further conforms with requirements hereinafter
glass, or both, with like construction that have been installed in
specified for coated overhead glass.
the same plane and elevation in the same building.
5.1.3 Kind CS—Flat glass conforming to the applicable
requirements of Specification C1036 or C1048, or both, and
3.2.11.1 banding—wide or narrow area(s) of nonuniformity
having a coating applied to one or more of the glass surfaces
withdemarcationthatappearsasalinearfeatureandmayoccur
that further conforms with the requirements hereinafter speci-
anywhere on a lite of coated glass.
fied for coated spandrel/non-vision glass.
3.2.11.2 edge to edge—gradient nonuniformity within a lite
of coated glass.
6. Requirements
3.2.11.3 lite to lite—nonuniformity between individual lites
6.1 These specifications apply to cut size glass only. For
of coated glass.
specifications of stock size glass and blemishes not listed,
3.2.11.4 mottling—splotchy or patchy nonuniformity (not to contact the manufacturer.
be confused with strain pattern; see X1.1.5).
6.2 All glass is to be inspected in transmission (unless
3.2.11.5 picture framing—perimeter nonuniformity within a otherwise noted) at a viewing angle of 90° to the specimen,
lite of coated glass. using a bright uniform background with diffused daylight
conditions, without direct sunlight. For factory inspection, the
3.2.12 pinhole—small blemish in which the coating is
specimen shall be placed a minimum of 12 in. from the light
entirely or partially absent.
source using uniform diffused background lighting with a
3.2.13 pyrolytic—method of manufacture of a type of coat-
minimum luminance of 1700 lux (160 fc) and maximum of
ing that applies the coating to hot glass, usually at the time of
2500 lux (230 fc) measured at the center of the glass surface
flat glass manufacturing.
closest to the light source. If a blemish is readily apparent
3.2.14 spot—a small opaque blemish on or in or under the
under these viewing conditions and detection distance as stated
coating.
in 6.3, the criteria in Table 1, Table 2,or Table 3 applies for
each kind of coated glass.
3.2.15 stock size—flat glass cut to standard dimensions that
will be cut to smaller sizes in a subsequent process.
6.3 Defect detection distance for coated vision glass (Kind
CV) is 10 ft (3.0 m) and for coated overhead glass (Kind CO)
3.2.16 vacuum deposition—method of manufacture of a
and coated spandrel/non-vision glass (Kind CS) is 15 ft (4.6 m)
typeofcoatingthatappliesthecoatinginavacuumchamberto
for both Range Nos. 1 and 2 (see Table 3).
stock size or cut size flat glass.
6.4 No more than two readily apparent blemishes are
3.2.17 vacuum sputtering—see vacuum deposition.
allowed in a 3-in. (75 mm) diameter circle, and no more than
4. Significance and Use
TABLE 1 Quality Specifications for Cut Size Coated Vision Glass
4.1 This specification groups coated glass according to
(Kind CV)
application. These groups are: vision, spandrel/non-vision, and
Central Area Outer Area
overhead. Similar but unique quality tolerances and inspection Blemish (maximum)
in. (mm) in. (mm)
1 3
criteriahavebeenoutlinedforeachapplication.Theglasstobe
Pinhole (size) ⁄16 (1.6) ⁄32 (2.4)
coated shall comply with the applicable provisions of Specifi-
1 3
Spot (size) ⁄16 (1.6) ⁄32 (2.4)
cations C1036 and C1048.
Coating Scratch (length) 2 (50) 3 (75)
4.2 Coating blemishes are an inherent part of the glass
coating process. In addition, coatings can be damaged as a
Mark/Contaminant (length) 2 (50) 3 (75)
result of improper transportation, storage, handling,
Coating Rub (length plus width) none allowed ⁄4 (19)
fabrication, or installation.
Crazing (length plus width) 2 (50) 3 (75)
4.3 Individual manufacturers should be contacted for rec-
ommended storage, handling, fabrication, installation, and
Corrosion none allowed none allowed
application guidelines.
C1376−21a
TABLE 2 Quality Specifications for Cut Size Coated Overhead
6.10 Nonuniformity for Coated Glass—The phenomenon of
Glass (Kind CO)
nonuniformity in color of pyrolytic and vacuum deposition
Central Area Outer Area
coated glass may be visible within an individual lite, or
Blemish (maximum)
in. (mm) in. (mm)
between lites of glass, in a particular building or curtain wall.
3 1
Pi
...

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. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: C1376 − 21 C1376 − 21a
Standard Specification for
Pyrolytic and Vacuum Deposition Coatings on Flat Glass
This standard is issued under the fixed designation C1376; 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
1.1 This specification covers the optical and aesthetic quality requirements for pyrolytic and vacuum deposition coatings applied
to on flat glass for use in building glazing.
1.2 The coatings covered are applied toon the glass using either pyrolytic or vacuum (sputtering)sputtering deposition methods
and are typically applied to control solar heat gain, energy performance, comfort level, and condensation and to enhance the
aesthetic of the building.
1.3 This specification addresses blemishes related to the coating only. It does not address glass blemishes, applied ceramic frits
to spandrel glass, and organic film opacifiers.
1.4 The Nonuniformity for Coated Glass requirements, given in 6.10, pertain to as installed in the building exterior glazing units
of vertical and sloped orientations.orientations as installed in the building exterior.
1.5 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical
conversions to SI units that are provided for information only and are not considered standard.
1.6 This international standard was developed in accordance with internationally recognized principles on standardization
established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued
by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
2. Referenced Documents
2.1 Reference to these documents shall be the latest issue unless otherwise specified by the authority applying this specification.
2.2 ASTM Standards:
C162 Terminology of Glass and Glass Products
C1036 Specification for Flat Glass
C1048 Specification for Heat-Strengthened and Fully Tempered Flat Glass
D2244 Practice for Calculation of Color Tolerances and Color Differences from Instrumentally Measured Color Coordinates
3. Terminology
3.1 Definitions:
This specification is under the jurisdiction of ASTM Committee C14 on Glass and Glass Products and is the direct responsibility of Subcommittee C14.08 on Flat Glass.
Current edition approved Feb. 1, 2021Sept. 1, 2021. Published March 2021November 2021. Originally approved in 1997. Last previous edition approved in 20152021
as C1376 – 15.C1376 – 21. DOI: 10.1520/C1376-21.10.1520/C1376-21A.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
C1376 − 21a
3.1.1 Refer to Terminology C162 or Specification C1036 or C1048, as appropriate.
3.1.2 blemishes in flat glass—refer to Specification C1036 or C1048, as appropriate.
3.1.3 These definitions do not apply to in-service damage.
3.2 Definitions of Terms Specific to This Standard:
3.2.1 coated overhead glass—glass used in an installation in which the lower edge of the glass is more than 6 ft (1.8 m) above
(the viewer’s) floor level or cannot be approached within 10 ft (3.0 m); the glass can usually but not always be viewed in both
transmission and reflection; the glass is usually sloping in from the vertical plane, however, may also be vertical or sloping out
from the vertical plane.
3.2.2 coated spandrel/non-vision glass—glass used in an installation in which the glass is only viewed in reflection from the
building’s exterior. Theexterior; the glass is usually installed vertically, however, may be at a slope to the vertical planeplane.
3.2.3 coated vision glass—glass used in an installation in which the lower edge of the glass is a maximum of 6 ft (1.8 m) above
(the viewer’s) floor level; the glass can be viewed in transmission or reflection; the glass is usually vertical, however, may also
be sloping in or out from the vertical plane; and the glass can be approached within 10 ft (3.0 m) or less. If the distance is greater
than 10 ft (3.0 m), see coated overhead glass.glass, which would apply.
3.2.4 coating rub—a surface abrasion of appreciable width that has partial,partial or complete,complete removal of the coating
producing a hazy appearance.
3.2.5 coating scratch—partial,partial or complete,complete removal of the coating along a thin straight or curved line.
3.2.6 corrosion—change in the color or level of reflected or transmitted light over all or part of the glass surface as a result of
degradation of the coating from external sources.
3.2.7 crazing—a random conglomeration of fine lines or cracks in the coating.
3.2.8 cut size—flat glass sheets cut to specific dimensions.dimensions for end use.
3.2.9 edge deletion—the process of removing a portion of the vacuum deposition coating from the glass surface typically within
1 inin. (25 mm) or less of all edges before insulating or laminating the glass.
3.2.10 mark/contaminant—a deposit of foreign material on the glass surface.surface of the glass or coating.
3.2.11 nonuniformity—obvious variation in reflected color of the coating color within a lite of coated glass, or between two or
more lites of coated glass of glass, or both, with like construction that have been installed in the same plane and elevation in the
same building, or both. building.
3.2.11.1 banding—wide or narrow area(s) of nonuniformity with demarcation that appears as a linear feature and may occur
anywhere on a lite.lite of coated glass.
3.2.11.2 edge to edge—gradient nonuniformity within a lite of coated glass.
3.2.11.3 lite to lite—nonuniformity between individual lites.lites of coated glass.
3.2.11.4 mottling—splotchy or patchy nonuniformity (not to be confused with strain pattern; see X1.1.5).
3.2.11.5 picture framing—perimeter nonuniformity within a lite of coated glass.
3.2.12 pinhole—small areablemish in which the coating is entirely or partially absent.
3.2.13 pyrolytic—term used to describe a method of manufacture of a coating; process type of coating that applies the coating to
hot glass, usually at the time of flat glass manufacturing.
C1376 − 21a
3.2.14 spot—a small,small opaque blemish in on or in or under the coating.
3.2.15 stock size—flat glass sheets cut to standard dimensions that will be cut to smaller sizes in a subsequent process.
3.2.16 vacuum deposition—term used to describe a method of manufacture of a coating; the process type of coating that applies
the coating in a vacuum chamber to stock size or cut size flat glass.
3.2.17 vacuum sputtering—see vacuum deposition.
4. Significance and Use
4.1 This specification groups coated glass according to application. These groups are: vision, spandrel/non-vision, and overhead.
Similar but unique quality tolerances and inspection guidelinescriteria have been outlined for each application. The glass to be
coated shall comply with the applicable provisions of Specifications C1036 and C1048.
4.2 Coating blemishes are an inherent part of the glass-coating glass coating process. In addition, coatings can be damaged as a
result of improper transportation, storage, handling, fabrication, or installation.
4.3 Individual manufacturers should be contacted for recommended storage, handling, fabrication, installation, and application
guidelines.
5. Classification
5.1 Kinds—Coated Pyrolytic or vacuum deposition coated flat glass furnished under this specification shall be of the following
kinds, as specified:
5.1.1 Kind CV—Flat transparent glass conforming to the applicable requirements of Specification C1036 or C1048, or both, and
having a coating applied to one or more of the glass surfaces which further conforms with the requirements hereinafter specified
for coated vision glass.
5.1.2 Kind CO—Flat transparent glass conforming to the applicable requirements of Specification C1036 or C1048, or both, and
having a coating applied to one or more of the glass surfaces which further conforms with requirements hereinafter specified for
coated overhead glass.
5.1.3 Kind CS—Flat glass conforming to the applicable requirements of Specification C1036 or C1048, or both, and having a
coating applied to one or more of the glass surfaces that further conforms with the requirements hereinafter specified for coated
spandrel/non-vision glass.
6. Requirements
6.1 These specifications apply to cut size glass only. For specifications of stock size glass and blemishes not listed, contact the
manufacturer.
6.2 All glass is to be inspected in transmission (unless otherwise noted) at a viewing angle of 90° to the specimen, using a bright
uniform background with diffused daylight conditions, without direct sunlight. For factory inspection, the specimen shall be placed
a minimum of 12 in. from the light source using uniform diffused background lighting with a minimum luminance of 1700 lux (160
foot-candles)fc) and maximum of 2500 lux (230 foot-candles)fc) measured at the center of the glass surface closest to the light
source. If a blemish is readily apparent under these viewing conditions and detection distance as stated in 6.3, the criteria in Table
1, Table 2, or Table 3 applies for each kind of coated glass.
6.3 Defect detection distance for coated vision glass (Kind CV) is 10 ft.ft (3.0 m) and for coated overhead glass (Kind CO) and
coated spandrel/non-vision glass (Kind CS) is 15 ft (4.6 m).(4.6 m) for both Range Nos. 1 and 2 (see Table 3).
6.4 No more than two readily apparent blemishes are allowed in a 3-in. (75 mm) diameter circle, and no more than five readily
apparent blemishes are allowed in a 12-in. (300 mm) diameter circle.
C1376 − 21a
TABLE 1 Quality Specifications for Cut Size Coated Vision Glass
(Kind CV)
Central Area, Outer Area,
Blemish
in. (mm) in. (mm)
Central Area Outer Area
Blemish (maximum)
in. (mm) in. (mm)
1 3
Pinhole ⁄16 (1.6) max ⁄32 (2.4) max
1 3
Pinhole (size) ⁄16 (1.6) ⁄32 (2.4)
1 3
Spot ⁄16 (1.6) max ⁄32 (2.4) max
1 3
Spot (size) ⁄16 (1.6) ⁄32 (2.4)
Coating Scratch 2 (50) max 3 (75) max
length length
Coating Scratch (length) 2 (50) 3 (75)
Mark/Contaminant 2 (50) max 3 (75) max
length length
Mark/Contaminant (length) 2 (50) 3 (75)
Coating Rub none allowed length plus width
not to exceed ⁄4
(19)
Coating Rub (length plus width) none allowed ⁄4 (19)
Crazing length plus width length plus width
not to exceed not to exceed
2 in. (50) max 3 in. (75) max
Crazing (length plus width) 2 (50) 3 (75)
Corrosion none allowed none allowed
TABLE 2 Quality Specifications for Cut Size Coated Overhead
Glass (Kind CO)
Central Area, Outer Area,
Blemish
in. (mm) in. (mm)
Central Area Outer Area
Blemish (maximum)
in. (mm) in. (mm)
3 1
Pinhole ⁄32 (2.4) max ⁄8 (3.2) max
3 1
Pinhole (size) ⁄32 (2.4) ⁄8 (3.2)
3 1
Spot ⁄32 (2.4) max ⁄8 (3.2) max
3 1
Spot (si
...