ASTM C448-88(2011)e1
(Test Method)Standard Test Methods for Abrasion Resistance of Porcelain Enamels
Standard Test Methods for Abrasion Resistance of Porcelain Enamels
SIGNIFICANCE AND USE
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.
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Designation: C448 − 88 (Reapproved 2011)
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.
ε NOTE—Test Method was corrected editorially in 2011
INTRODUCTION
Thistestisameansofquantifyingtheabrasionresistanceofporcelainenamelsthroughsteady-state
subsurfaceabrasivewearwithstainlesssteelballbearings.Achangeinglossorweightlossisreported
that can, through further evaluation, be correlated to the service life of the enameled ware.
1. Scope the unabraded 45° specular gloss is 30 gloss units or less. It
consists of determining the weight loss by a specified abrasive
1.1 Thesetestmethodscoverdeterminationoftheresistance
treatment and multiplying this weight loss by an adjustment
of porcelain enamels to surface abrasion and subsurface
factor associated with each abrasive tester, lot of abrasive, and
abrasion.
lot of calibrated plate glass standards used. The adjusted
1.2 This standard does not purport to address all of the
weight loss is taken as an index of resistance to surface
safety concerns, if any, associated with its use. It is the
abrasion.
responsibility of the user of this standard to establish appro-
priate safety and health practices and determine the applica-
3.3 The third test is intended for the determination of the
bility of regulatory limitations prior to use.
resistance of porcelain enamels to subsurface abrasion. It
consists of determining the slope of the linear portion of the
2. Referenced Documents
abrasion time-weight loss curve and multiplying by an adjust-
2.1 ASTM Standards:
ment factor associated with each abrasion tester, lot of
C346Test Method for 45-deg Specular Gloss of Ceramic
abrasive, and lot of calibrated plate glass standards used. The
Materials
adjusted slope is taken as an index of resistance to subsurface
abrasion.
3. Summary of Test Methods
3.1 The first of the tests described herein is intended for the
4. Significance and Use
determinationoftheresistancetosurfaceabrasionofporcelain
4.1 Whenaporcelainenamelisfirstsubjectedtoabrasionof
enamels for which the unabraded 45° specular gloss is more
the type involved in these tests, the rate of wear or attrition is
than 30 gloss units. It consists essentially of measuring the
relatively low. As the enamel is subjected to continued
specular gloss of the specimens before and after a specified
abrasion, the rate of wear increases until it reaches a steady
abrasive treatment of the surface, and taking the percentage of
value. Thereafter, the rate of wear remains almost constant
theoriginalspecularglossthatisretainedaftertreatmentasthe
until the enamel is penetrated and the underlying ground coat
surface abrasion index.
ormetalexposed.Theabrasionthatoccursduringtheperiodof
3.2 The second test is intended for the determination of the
increasing rate-of-weight loss is defined as surface abrasion
resistance to surface abrasion of porcelain enamels for which
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
These test methods are under the jurisdiction of ASTM Committee B08 on
Metallic and Inorganic Coatingsand are the direct responsibility of Subcommittee
abrasion that occurs during the period of steady rate-of-weight
B08.12 on Materials for Porcelain Enamel and Ceramic-Metal Systems.
loss is defined as subsurface abrasion and results in the
Current edition approved April 1, 2011. Published April 2011. Originally
destruction of the continuity of the coating.These two types of
approved in 1959. Last previous edition approved in 2006 as C448–88 (2006).
DOI: 10.1520/C0448-88R11E01.
abrasion are not necessarily proportional, and since it is
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
desirable to be able to determine the resistance of porcelain
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
enamel to both types of abrasion, it is necessary to deal with
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. each one separately.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
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C448 − 88 (2011)
5. Apparatus 7. Reference Standards
5.1 Balance, having a capacity of approximately 200 g and 7.1 Specimens of standard calibrated polished plate glass
accurate to 0.0001 g. which shows a coefficient of variation no greater than 1.5%
3 when tested for surface abrasion in accordance with the
5.2 Alloy Balls —Rust-resisting alloy balls of the type used
procedure as specified in Section 10, and which meets require-
forbearings, ⁄32in.(4mm)indiameter.About4lb(1.8kg)are
ments of Table A1.4 shall be used as reference standards.
required. Second-grade balls are satisfactory.
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
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
alcohol is not available, isopropyl alcohol or acetone may be used, but
6. Abrasives
pure ethyl alcohol is recommended if available. Avoid alcohol denatured
6.1 For the surface abrasion tests the−70 +100-mesh frac-
withaningredientoflowvolatility,whichwillremainasasurfacefilmon
thespecimenwhenusedtorinseitbeforeoraftertreatment.Surfacefilms
tion of Pennsylvania-type glass sand, preferably as ground
may significantly affect gloss readings.
from quartzite (quartz rock), shall be used. For the subsurface
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
Units
3 10.1 Marking of Specimens and Determining Initial 45°
Balls meeting the requirements of this paragraph are available from the Mobay
Corporation, 5601 Eastern Avenue, Baltimore, MD 21224.
Specular Gloss—Mark each specimen so that its orientation
Suitable instruments are available from: Pacific Scientific Company, Gardner/
maybecontrolled.Amarkonthebackatoneedgewillsuffice.
Neotec Instrument Division, 2431 Linden Lane, Silver Spring, MD 20910; and
Place this edge against the specimen guide on the gloss head
Hunter Lab, 11495 Sunset Hills Road, Reston, VA 22090.
for the first reading. Then make three other readings, turning
A suitable apparatus is the P.E.I. Abrasion Tester, manufactured by the
Keystone Electric Co., 2807 Annapolis Road, Baltimore, MD 21230.
the specimen clockwise through 90° between readings.
These standard materials are available from the Mobay Corp., 5601 Eastern
Ave., Baltimore, MD 21224. NOTE 3—The measured gloss of light-transmitting specimens of such
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C448 − 88 (2011)
materials as transparent or translucent glass or plastic may be affected by
individual retaining ring assemblies, another 175 6 0.15 g of
light reflected from the back side of the specimen or transmitted through
ball bearings shall be used in subsequent testing cycles.
the specimen from the room. To minimize errors from this source, the
10.5.1.2 Scrub the abraded portion very lightly with a clean
following precautions should be taken:
(1) Roughen the back of transparent specimens to eliminate specular sponge that has been saturated with warm water, rinse with
reflection from this surface.
warmrunningwater,andwhilestillwet,rinsewithalcoholand
(2) Cover back and edges of light-transmitting specimens with an
place in a vertical position to dry.
opaque black cloth when measuring gloss to prevent normal room
illumination from being transmitted through the specimen, or light from
10.6 DeterminingFinal45°SpecularGloss—Makethefinal
the instrument from being reflected back through the specimen from a
gloss readings within 15 min after the specimens have been
light surface in contact with the back of the specimen.This is particularly
giventhefinalrinsing,followingtheprocedureoutlinein10.1.
important when using a glossmeter with the specimen holder on top.
(3) Put no labels near the center of light-transmitting specimens.
10.7 Computation of Surface Abrasion Index—For each of
10.2 Determining Correct Abrasion Time— The correct
thefourorientationsofthespecimens,dividethefinalspecular
abrasion time is the time required to reduce the 45° specular
gloss reading by the initial reading and multiply by 100. The
gloss of a standard plate glass specimen to 53 6 1%.
average percentage residual specular gloss for the four posi-
Determine this time by abrading six standard plate glass
tions shall be taken as the surface abrasion index of the
specimens and calculating the average percentage 45° specular
specimen. The average index of six specimens after treatment
gloss retained. A good trial time is 6.117 min (184 counts) on
shall be taken as the abrasion index of a given index of
machines manufactured prior to July 1981, or 4.367 min (150
enameled metal.
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
IntroducingAbrasiveMixture—Centereachspecimeninoneof been tested. If less than nine samples are to be tested, any arrangement
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
uniformly. The amount of tightening shall be just sufficient to
10.8 Use of Standard Plate Glass Specimens—As a check
provide a watertight seal between the retaining ring and the
on the performance of the apparatus, test standard, calibrated,
specimen. Introduce an abrasive charge of 175 6 0.15 g of ⁄32
plate glass specimens at regular intervals. If the computed
-in. (4-mm) rust-resisting alloy balls, 3 6 0.01 g of−70+100
surface abrasion index obtained in a check test of six standard
meshPennsylvania-typeglasssand,and20 60.2mLofwater,
glass plates falls outside the limits 52.0 to 54.0 but within the
in that order, through the hole in the top of each retaining ring.
limits51.5to54.5,adjusttheabrasiontimeinaccordancewith
After the abrasive charge is introduced, seal the hole in the top
10.2.Ifavaluebelow51.5orabove54.5isobtained,defective
of the retaining ring with a cork or rubber stopper.
technique or equipment is indicated, and the source of diffi-
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 t
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