ASTM C448-88(2016)

Standard Test Methods for Abrasion Resistance of Porcelain Enamels

SIGNIFICANCE AND USE
4.1 When a porcelain enamel is first subjected to abrasion of the type involved in these tests, the rate of wear or attrition is relatively low. As the enamel is subjected to continued abrasion, the rate of wear increases until it reaches a steady value. Thereafter, the rate of wear remains almost constant until the enamel is penetrated and the underlying ground coat or metal exposed. The abrasion that occurs during the period of increasing rate-of-weight loss is defined as surface abrasion and results in reduced gloss and cleanability with high-gloss enamels and a modification of color, appearance, or surface texture, or combination thereof with low-gloss enamels. The abrasion that occurs during the period of steady rate-of-weight loss is defined as subsurface abrasion and results in the destruction of the continuity of the coating. These two types of abrasion are not necessarily proportional, and since it is desirable to be able to determine the resistance of porcelain enamel to both types of abrasion, it is necessary to deal with each one separately.
SCOPE
1.1 These test methods cover determination of the resistance of porcelain enamels to surface abrasion and subsurface abrasion.  
1.2 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: 31-Oct-2016
• ICS: 25.220.50 - Enamels
• Technical Committee: B08 - Metallic and Inorganic Coatings
• Drafting Committee: B08.12 - Materials for Porcelain Enamel and Ceramic-Metal Systems

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NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.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: C448 − 88 (Reapproved 2016)
Standard Test Methods for
Abrasion Resistance of Porcelain Enamels
This standard is issued under the fixed designation C448; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
INTRODUCTION
Thistestisameansofquantifyingtheabrasionresistanceofporcelainenamelsthroughsteady-state
subsurfaceabrasivewearwithstainlesssteelballbearings.Achangeinglossorweightlossisreported
that can, through further evaluation, be correlated to the service life of the enameled ware.
1. Scope consists of determining the weight loss by a specified abrasive
treatment and multiplying this weight loss by an adjustment
1.1 Thesetestmethodscoverdeterminationoftheresistance
factor associated with each abrasive tester, lot of abrasive, and
of porcelain enamels to surface abrasion and subsurface
lot of calibrated plate glass standards used. The adjusted
abrasion.
weight loss is taken as an index of resistance to surface
1.2 This standard does not purport to address all of the
abrasion.
safety concerns, if any, associated with its use. It is the
3.3 The third test is intended for the determination of the
responsibility of the user of this standard to establish appro-
resistance of porcelain enamels to subsurface abrasion. It
priate safety and health practices and determine the applica-
consists of determining the slope of the linear portion of the
bility of regulatory limitations prior to use.
abrasion time-weight loss curve and multiplying by an adjust-
ment factor associated with each abrasion tester, lot of
2. Referenced Documents
abrasive, and lot of calibrated plate glass standards used. The
2.1 ASTM Standards:
adjusted slope is taken as an index of resistance to subsurface
C346Test Method for 45-deg Specular Gloss of Ceramic
abrasion.
Materials
4. Significance and Use
3. Summary of Test Methods
4.1 Whenaporcelainenamelisfirstsubjectedtoabrasionof
3.1 The first of the tests described herein is intended for the
the type involved in these tests, the rate of wear or attrition is
determinationoftheresistancetosurfaceabrasionofporcelain
relatively low. As the enamel is subjected to continued
enamels for which the unabraded 45° specular gloss is more
abrasion, the rate of wear increases until it reaches a steady
than 30 gloss units. It consists essentially of measuring the
value. Thereafter, the rate of wear remains almost constant
specular gloss of the specimens before and after a specified
until the enamel is penetrated and the underlying ground coat
abrasive treatment of the surface, and taking the percentage of
ormetalexposed.Theabrasionthatoccursduringtheperiodof
theoriginalspecularglossthatisretainedaftertreatmentasthe
increasing rate-of-weight loss is defined as surface abrasion
surface abrasion index.
and results in reduced gloss and cleanability with high-gloss
enamels and a modification of color, appearance, or surface
3.2 The second test is intended for the determination of the
resistance to surface abrasion of porcelain enamels for which texture, or combination thereof with low-gloss enamels. The
abrasion that occurs during the period of steady rate-of-weight
the unabraded 45° specular gloss is 30 gloss units or less. It
loss is defined as subsurface abrasion and results in the
destruction of the continuity of the coating.These two types of
These test methods are under the jurisdiction of ASTM Committee B08 on
abrasion are not necessarily proportional, and since it is
Metallic and Inorganic Coatings and are the direct responsibility of Subcommittee
desirable to be able to determine the resistance of porcelain
B08.12 on Materials for Porcelain Enamel and Ceramic-Metal Systems.
enamel to both types of abrasion, it is necessary to deal with
Current edition approved Nov. 1, 2016. Published November 2016. Originally
each one separately.
approved in 1959. Last previous edition approved in 2011 as C448–88 (2011).
DOI: 10.1520/C0448-88R16.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or 5. Apparatus
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
5.1 Balance, having a capacity of approximately 200 g and
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. accurate to 0.0001 g.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
C448 − 88 (2016)
5.2 Alloy Balls —Rust-resisting alloy balls of the type used when tested for surface abrasion in accordance with the
forbearings, ⁄32in.(4mm)indiameter.About4lb(1.8kg)are procedure as specified in Section 10, and which meets require-
required. Second-grade balls are satisfactory. ments of Table A1.4 shall be used as reference standards.
5.3 Apparatus for Measuring Specular Gloss, conforming
8. Test Specimens
to the requirements of Test Method C346 and having a
3 1
8.1 Test specimens shall be 4 ⁄8 6 ⁄4 in. (111.1 6 6.4 mm)
repeatable precision of not less than 60.5 gloss unit. Means
square,andmaybepreparedbyenamelingmetalblanksofthat
shall be provided for positioning the specimen, with respect to
size or by cutting a larger piece. Specimens for the weight loss
the gloss head, so that, for a given orientation, the position of
tests should not exceed the capacity of the analytical balance
the specimen during the final gloss reading may be controlled
selected for obtaining the weights of the specimens. When
to within ⁄16 in. (1.6 mm) of that during the original gloss
gloss measurements are to be made, the specimens tested
reading.
should be as flat and free of orange peel or wavy surface as
NOTE 1—Care should be taken to keep the interior of the glossmeter
possible. Variations from flatness decrease the accuracy of
free of dust. If a glossmeter is used with the opening at the top, a piece of
gloss measurements.
phenolicresinorsimilarmaterialshouldbeplacedovertheopeningwhen
the instrument is not in use. The lenses should be cleaned at regular
8.2 Six specimens shall be tested for each determination of
intervals with a soft camel’s-hair brush.
resistance to surface abrasion or resistance to subsurface
The black gloss standard should be kept free of scratches, and should
abrasion.
be protected by wrapping with a soft cloth when not in use.
5.4 Apparatus for Oscillating Specimens —The apparatus
9. Specimen Preparation
used for oscillating the specimens during test shall impart to
9.1 Before making any measurements, wash each specimen
nine specimens simultaneously a horizontal circular motion
7 with a soft sponge moistened with a warm 1% solution of
suchthateverypointoneachspecimendescribesacircle ⁄8in.
trisodium phosphate (distilled water not essential) and rinse in
(22.2mm)indiameter.Theapparatusshallbeprovidedwithan
warm, running tap water. If, when rinsing, the water gathers in
automatic timing device capable of being preset to within 1 s
drops on the surface, repeat the washing treatment until the
of the desired time and shall operate at a frequency of 300 6
rinse water spreads evenly. While the specimen is still wet,
3cpm(formachinemanufacturedpriortoJuly1981)or345 6
rinse it with ethyl alcohol. A small stream of alcohol from an
3 cpm (for machines manufactured after July 1981). The
ordinary chemical wash bottle will suffice for rinsing. Pure
apparatus shall be operated on a firm and level surface.
ethyl alcohol is preferable, but if it is not available, ethyl
5.5 Retaining Rings—The retaining rings shall be con-
alcohol that has been denatured with up to 5 % of a
structed of metal lined with rubber. The inside height and
noncorrosive, highly volatile organic compound such as
3 1
diameter of the rubber-lined ring shall be 1 ⁄16 6 ⁄16 in. (30.2
methyl alcohol may be used.Allow the specimens to air dry in
7 1
6 1.6 mm) and 3 ⁄16 6 ⁄16 in. (87.3 6 1.6 mm), respectively.
a vertical position and then place in a desiccator. This will
Provision shall be made for clamping the retaining ring to an
prevent damage and moisture absorption of the specimens
enameled metal specimen to produce a watertight seal. Means
whichcanadverselyaffecttheweightvalues.Glossandweight
shall be provided for introducing an abrasive charge after the
determinationsshouldbeobtainedwithina15-minperiodafter
specimen is secured. Nine retaining rings are required.
the specimens have been cleaned and placed in the desiccator.
5.6 Buret, of suitable capacity to deliver 20 mL of water at
NOTE 2—Other denaturants, approved by the U. S. Bureau of Internal
20°C (68°F).
Revenue, that are not objectionable for this use are ethyl ether and
benzene, either alone or in combination with methyl alcohol. If ethyl
6. Abrasives
alcohol is not available, isopropyl alcohol or acetone may be used, but
pure ethyl alcohol is recommended if available. Avoid alcohol denatured
6.1 For the surface abrasion tests the−70 +100-mesh frac-
withaningredientoflowvolatility,whichwillremainasasurfacefilmon
tion of Pennsylvania-type glass sand, preferably as ground
thespecimenwhenusedtorinseitbeforeoraftertreatment.Surfacefilms
from quartzite (quartz rock), shall be used. For the subsurface
may significantly affect gloss readings.
abrasion test No. 80 grit aluminum oxide abrasive medium
10. Resistance to Surface Abrasion of Porcelain Enamels
shall be used.
Having 45° Specular Gloss of More than 30 Gloss
7. Reference Standards
Units
7.1 Specimens of standard calibrated polished plate glass
10.1 Marking of Specimens and Determining Initial 45°
which shows a coefficient of variation no greater than 1.5%
Specular Gloss—Mark each specimen so that its orientation
maybecontrolled.Amarkonthebackatoneedgewillsuffice.
Place this edge against the specimen guide on the gloss head
Balls meeting the requirements of this paragraph are available from the Mobay
for the first reading. Then make three other readings, turning
Corporation, 5601 Eastern Avenue, Baltimore, MD 21224.
Suitable instruments are available from: Pacific Scientific Company, Gardner/ the specimen clockwise through 90° between readings.
Neotec Instrument Division, 2431 Linden Lane, Silver Spring, MD 20910; and
NOTE 3—The measured gloss of light-transmitting specimens of such
Hunter Lab, 11495 Sunset Hills Road, Reston, VA 22090.
materials as transparent or translucent glass or plastic may be affected by
A suitable apparatus is the P.E.I. Abrasion Tester, manufactured by the
light reflected from the back side of the specimen or transmitted through
Keystone Electric Co., 2807 Annapolis Road, Baltimore, MD 21230.
These standard materials are available from the Mobay Corp., 5601 Eastern the specimen from the room. To minimize errors from this source, the
Ave., Baltimore, MD 21224. following precautions should be taken:
C448 − 88 (2016)
(1)Roughenthebackoftransparentspecimenstoeliminate individual retaining ring assemblies, another 175 6 0.15 g of
specular reflection from this surface. ball bearings shall be used in subsequent testing cycles.
(2)Cover back and edges of light-transmitting specimens
10.5.1.2 Scrub the abraded portion very lightly with a clean
with an opaque black cloth when measuring gloss to prevent
sponge that has been saturated with warm water, rinse with
normal room illumination from being transmitted through the
warmrunningwater,andwhilestillwet,rinsewithalcoholand
specimen, or light from the instrument from being reflected
place in a vertical position to dry.
back through the specimen from a light surface in contact with
10.6 DeterminingFinal45°SpecularGloss—Makethefinal
the back of the specimen. This is particularly important when
gloss readings within 15 min after the specimens have been
using a glossmeter with the specimen holder on top.
giventhefinalrinsing,followingtheprocedureoutlinein10.1.
(3)Put no labels near the center of light-transmitting
specimens.
10.7 Computation of Surface Abrasion Index—For each of
thefourorientationsofthespecimens,dividethefinalspecular
10.2 Determining Correct Abrasion Time— The correct
gloss reading by the initial reading and multiply by 100. The
abrasion time is the time required to reduce the 45° specular
average percentage residual specular gloss for the four posi-
gloss of a standard plate glass specimen to 53 6 1%.
tions shall be taken as the surface abrasion index of the
Determine this time by abrading six standard plate glass
specimen. The average index of six specimens after treatment
specimens and calculating the average percentage 45° specular
shall be taken as the abrasion index of a given index of
gloss retained. A good trial time is 6.117 min (184 counts) on
enameled metal.
machines manufactured prior to July 1981, or 4.367 min (150
counts) on machines manufactured after July 1981.
NOTE 4—If it is desirable, nine samples may be treated simultaneously,
10.3 Securing Specimens to Table of Abrasion Tester and this procedure being repeated until six specimens of each sample have
been tested. If less than nine samples are to be tested, any arrangement
IntroducingAbrasiveMixture—Centereachspecimeninoneof
desired may be used and the arrangement may be such that the number of
the nine available positions and secure by means of the
operations required to test six specimens of each sample is a minimum.
retaining ring. Tighten the two wing nuts simultaneously and
10.8 Use of Standard Plate Glass Specimens—As a check
uniformly. The amount of tightening shall be just sufficient to
on the performance of the apparatus, test standard, calibrated,
provide a watertight seal between the retaining ring and the
5 plate glass specimens at regular intervals. If the computed
specimen. Introduce an abrasive charge of 175 6 0.15 g of ⁄32
surface abrasion index obtained in a check test of six standard
-in. (4-mm) rust-resisting alloy balls, 3 6 0.01 g of−70+100
glass plates falls outside the limits 52.0 to 54.0 but within the
meshPennsylvania-typeglasssand,and20 60.2mLofwater,
limits51.5to54.5,adjusttheabrasiontimeinaccordancewith
in that order, through the hole in the top of each retaining ring.
10.2.Ifavaluebelow51.5orabove54.5isobtained,defective
After the abrasive charge is introduced, seal the hole in the top
technique or equipment is indicated, and the source of diffi-
of the retaining ring with a cork or rubber stopper.
culty should be found and remedied.
10.4 Treatment of Specimens—Set the automatic timing
device for the previously determined time required to reduce
NOTE 5—This check test need not be made each time enameled metal
specimens are tested.The ti
...

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.
´1
Designation: C448 − 88 (Reapproved 2011) C448 − 88 (Reapproved 2016)
Standard Test Methods for
Abrasion Resistance of Porcelain Enamels
This standard is issued under the fixed designation C448; 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.
ε NOTE—Test Method was corrected editorially in 2011
INTRODUCTION
This test is a means of quantifying the abrasion resistance of porcelain enamels through steady-state
subsurface abrasive wear with stainless steel ball bearings. A change in gloss or weight loss is reported
that can, through further evaluation, be correlated to the service life of the enameled ware.
1. Scope
1.1 These test methods cover determination of the resistance of porcelain enamels to surface abrasion and subsurface abrasion.
1.2 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.
2. Referenced Documents
2.1 ASTM Standards:
C346 Test Method for 45-deg Specular Gloss of Ceramic Materials
3. Summary of Test Methods
3.1 The first of the tests described herein is intended for the determination of the resistance to surface abrasion of porcelain
enamels for which the unabraded 45° specular gloss is more than 30 gloss units. It consists essentially of measuring the specular
gloss of the specimens before and after a specified abrasive treatment of the surface, and taking the percentage of the original
specular gloss that is retained after treatment as the surface abrasion index.
3.2 The second test is intended for the determination of the resistance to surface abrasion of porcelain enamels for which the
unabraded 45° specular gloss is 30 gloss units or less. It consists of determining the weight loss by a specified abrasive treatment
and multiplying this weight loss by an adjustment factor associated with each abrasive tester, lot of abrasive, and lot of calibrated
plate glass standards used. The adjusted weight loss is taken as an index of resistance to surface abrasion.
3.3 The third test is intended for the determination of the resistance of porcelain enamels to subsurface abrasion. It consists of
determining the slope of the linear portion of the abrasion time-weight loss curve and multiplying by an adjustment factor
associated with each abrasion tester, lot of abrasive, and lot of calibrated plate glass standards used. The adjusted slope is taken
as an index of resistance to subsurface abrasion.
4. Significance and Use
4.1 When a porcelain enamel is first subjected to abrasion of the type involved in these tests, the rate of wear or attrition is
relatively low. As the enamel is subjected to continued abrasion, the rate of wear increases until it reaches a steady value.
Thereafter, the rate of wear remains almost constant until the enamel is penetrated and the underlying ground coat or metal
exposed. The abrasion that occurs during the period of increasing rate-of-weight loss is defined as surface abrasion and results in
reduced gloss and cleanability with high-gloss enamels and a modification of color, appearance, or surface texture, or combination
These test methods are under the jurisdiction of ASTM Committee B08 on Metallic and Inorganic Coatings and are the direct responsibility of Subcommittee B08.12
on Materials for Porcelain Enamel and Ceramic-Metal Systems.
Current edition approved April 1, 2011Nov. 1, 2016. Published April 2011November 2016. Originally approved in 1959. Last previous edition approved in 20062011 as
C448 – 88 (2006).(2011). DOI: 10.1520/C0448-88R11E01.10.1520/C0448-88R16.
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
C448 − 88 (2016)
thereof with low-gloss enamels. The abrasion that occurs during the period of steady rate-of-weight loss is defined as subsurface
abrasion and results in the destruction of the continuity of the coating. These two types of abrasion are not necessarily proportional,
and since it is desirable to be able to determine the resistance of porcelain enamel to both types of abrasion, it is necessary to deal
with each one separately.
5. Apparatus
5.1 Balance, having a capacity of approximately 200 g and accurate to 0.0001 g.
5.2 Alloy Balls —Rust-resisting alloy balls of the type used for bearings, ⁄32 in. (4 mm) in diameter. About 4 lb (1.8 kg) are
required. Second-grade balls are satisfactory.
5.3 Apparatus for Measuring Specular Gloss, conforming to the requirements of Test Method C346 and having a repeatable
precision of not less than 60.5 gloss unit. Means shall be provided for positioning the specimen, with respect to the gloss head,
so that, for a given orientation, the position of the specimen during the final gloss reading may be controlled to within ⁄16 in. (1.6
mm) of that during the original gloss reading.
NOTE 1—Care should be taken to keep the interior of the glossmeter free of dust. If a glossmeter is used with the opening at the top, a piece of phenolic
resin or similar material should be placed over the opening when the instrument is not in use. The lenses should be cleaned at regular intervals with a
soft camel’s-hair brush.
The black gloss standard should be kept free of scratches, and should be protected by wrapping with a soft cloth when not in use.
5.4 Apparatus for Oscillating Specimens —The apparatus used for oscillating the specimens during test shall impart to nine
specimens simultaneously a horizontal circular motion such that every point on each specimen describes a circle ⁄8 in. (22.2 mm)
in diameter. The apparatus shall be provided with an automatic timing device capable of being preset to within 1 s of the desired
time and shall operate at a frequency of 300 6 3 cpm (for machine manufactured prior to July 1981) or 345 6 3 cpm (for machines
manufactured after July 1981). The apparatus shall be operated on a firm and level surface.
5.5 Retaining Rings—The retaining rings shall be constructed of metal lined with rubber. The inside height and diameter of the
3 1 7 1
rubber-lined ring shall be 1 ⁄16 6 ⁄16 in. (30.2 6 1.6 mm) and 3 ⁄16 6 ⁄16 in. (87.3 6 1.6 mm), respectively. Provision shall be
made for clamping the retaining ring to an enameled metal specimen to produce a watertight seal. Means shall be provided for
introducing an abrasive charge after the specimen is secured. Nine retaining rings are required.
5.6 Buret, of suitable capacity to deliver 20 mL of water at 20°C (68°F).
6. Abrasives
6.1 For the surface abrasion tests the −70 +100-mesh fraction of Pennsylvania-type glass sand, preferably as ground from
quartzite (quartz rock), shall be used. For the subsurface abrasion test No. 80 grit aluminum oxide abrasive medium shall be used.
7. Reference Standards
7.1 Specimens of standard calibrated polished plate glass which shows a coefficient of variation no greater than 1.5 % when
tested for surface abrasion in accordance with the procedure as specified in Section 10, and which meets requirements of Table
A1.4 shall be used as reference standards.
8. Test Specimens
3 1
8.1 Test specimens shall be 4 ⁄8 6 ⁄4 in. (111.1 6 6.4 mm) square, and may be prepared by enameling metal blanks of that size
or by cutting a larger piece. Specimens for the weight loss tests should not exceed the capacity of the analytical balance selected
for obtaining the weights of the specimens. When gloss measurements are to be made, the specimens tested should be as flat and
free of orange peel or wavy surface as possible. Variations from flatness decrease the accuracy of gloss measurements.
8.2 Six specimens shall be tested for each determination of resistance to surface abrasion or resistance to subsurface abrasion.
9. Specimen Preparation
9.1 Before making any measurements, wash each specimen with a soft sponge moistened with a warm 1 % solution of trisodium
phosphate (distilled water not essential) and rinse in warm, running tap water. If, when rinsing, the water gathers in drops on the
surface, repeat the washing treatment until the rinse water spreads evenly. While the specimen is still wet, rinse it with ethyl
alcohol. A small stream of alcohol from an ordinary chemical wash bottle will suffice for rinsing. Pure ethyl alcohol is preferable,
but if it is not available, ethyl alcohol that has been denatured with up to 5 % of a noncorrosive, highly volatile organic compound
such as methyl alcohol may be used. Allow the specimens to air dry in a vertical position and then place in a desiccator. This will
Balls meeting the requirements of this paragraph are available from the Mobay Corporation, 5601 Eastern Avenue, Baltimore, MD 21224.
Suitable instruments are available from: Pacific Scientific Company, Gardner/Neotec Instrument Division, 2431 Linden Lane, Silver Spring, MD 20910; and Hunter Lab,
11495 Sunset Hills Road, Reston, VA 22090.
A suitable apparatus is the P.E.I. Abrasion Tester, manufactured by the Keystone Electric Co., 2807 Annapolis Road, Baltimore, MD 21230.
These standard materials are available from the Mobay Corp., 5601 Eastern Ave., Baltimore, MD 21224.
C448 − 88 (2016)
prevent damage and moisture absorption of the specimens which can adversely affect the weight values. Gloss and weight
determinations should be obtained within a 15-min period after the specimens have been cleaned and placed in the desiccator.
NOTE 2—Other denaturants, approved by the U. S. Bureau of Internal Revenue, that are not objectionable for this use are ethyl ether and benzene, either
alone or in combination with methyl alcohol. If ethyl alcohol is not available, isopropyl alcohol or acetone may be used, but pure ethyl alcohol is
recommended if available. Avoid alcohol denatured with an ingredient of low volatility, which will remain as a surface film on the specimen when used
to rinse it before or after treatment. Surface films may significantly affect gloss readings.
10. Resistance to Surface Abrasion of Porcelain Enamels Having 45° Specular Gloss of More than 30 Gloss Units
10.1 Marking of Specimens and Determining Initial 45° Specular Gloss—Mark each specimen so that its orientation may be
controlled. A mark on the back at one edge will suffice. Place this edge against the specimen guide on the gloss head for the first
reading. Then make three other readings, turning the specimen clockwise through 90° between readings.
NOTE 3—The measured gloss of light-transmitting specimens of such materials as transparent or translucent glass or plastic may be affected by light
reflected from the back side of the specimen or transmitted through the specimen from the room. To minimize errors from this source, the following
precautions should be taken:
(1) Roughen the back of transparent specimens to eliminate specular reflection from this surface.
(1) Roughen the back of transparent specimens to eliminate specular reflection from this surface.
(2) Cover back and edges of light-transmitting specimens with an opaque black cloth when measuring gloss to prevent normal
room illumination from being transmitted through the specimen, or light from the instrument from being reflected back through
the specimen from a light surface in contact with the back of the specimen. This is particularly important when using a glossmeter
with the specimen holder on top.
(3) Put no labels near the center of light-transmitting specimens.
(2) Cover back and edges of light-transmitting specimens with an opaque black cloth when measuring gloss to prevent normal room illumination from
being transmitted through the specimen, or light from the instrument from being reflected back through the specimen from a light surface in contact with
the back of the specimen. This is particularly important when using a glossmeter with the specimen holder on top.
(3) Put no labels near the center of light-transmitting specimens.
10.2 Determining Correct Abrasion Time— The correct abrasion time is the time required to reduce the 45° specular gloss of
a standard plate glass specimen to 53 6 1 %. Determine this time by abrading six standard plate glass specimens and calculating
the average percentage 45° specular gloss retained. A good trial time is 6.117 min (184 counts) on machines manufactured prior
to July 1981, or 4.367 min (150 counts) on machines manufactured after July 1981.
10.3 Securing Specimens to Table of Abrasion Tester and Introducing Abrasive Mixture—Center each specimen in one of the
nine available positions and secure by means of the retaining ring. Tighten the two wing nuts simultaneously and uniformly. The
amount of tightening shall be just sufficient to provide a watertight seal between the retaining ring and the specimen. Introduce
an abrasive charge of 175 6 0.15 g of ⁄32 -in. (4-mm) rust-resisting alloy balls, 3 6 0.01 g of −70 +100 mesh Pennsylvania-type
glass sand, and 20 6 0.2 mL of water, in that order, through the hole in the top of each retaining ring. After the abrasive charge
is introduced, seal the hole in the top of the retaining ring with a cork or rubber stopper.
10.4 Treatment of Specimens—Set the automatic timing device for the previously determined time required to reduce the 45°
specular gloss of a standard plate glass specimen to 53 %. Set the selector switch to the “automatic” position and close the toggle
switch, starting the oscillator. The abrasion tester will then stop after the prescribed abrasion time.
10.5 Cleaning Specimens after Treatment:
10.5.1 Clean the sample specimens and equipment as follows:
10.5.1.1 Immediately after treatment, loosen the wing nuts that secure the specimens to the abrasion tester. Carefully remove
the sample panel, retaining ring apparatus and abrasive medium as a sealed unit. (This can be accomplished by compressing the
panel to the retaining ring apparatus with the hands and rotating the ass
...