ASTM C756-87(2016)
(Test Method)Standard Test Method for Cleanability of Surface Finishes
Standard Test Method for Cleanability of Surface Finishes
SIGNIFICANCE AND USE
4.1 This test method was developed to guide the user in selecting a finish coating or material that is resistant to soiling in a particular application.
4.2 The numerical values derived by this test method enables the user to rank finish coatings and materials in regard to soil retention or ease of soil removal.
SCOPE
1.1 This test method covers the numerical evaluation of the ease or difficulty of cleaning soiled surface finishes. This test method is applicable to all surface finishes not affected by water.
1.2 Values given in SI units are to be regarded as the standard. Inch-pound units are provided for information only.
1.3 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
Buy Standard
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NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.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: C756 − 87 (Reapproved 2016)
Standard Test Method for
Cleanability of Surface Finishes
This standard is issued under the fixed designation C756; 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.
INTRODUCTION
This test provides a procedure to quantify the cleanability of acid-resistant porcelain enamel using
a fluorescent water-soluble soil in agent, a reproducible machine-wiping technique, and a means of
measuring the amount of residual soil by fluorescence.
1. Scope inasimilarmanner.Thecleanabilityindexofthesurfaceunder
testisexpressedastheratioofthefluorescenceofthesolutions
1.1 This test method covers the numerical evaluation of the
extracted from the test surface and from the standard reference
ease or difficulty of cleaning soiled surface finishes. This test
surface. Cleanability indexes greater than 1.0 indicate that the
method is applicable to all surface finishes not affected by
test surface is more difficult to clean than the standard
water.
reference surface, while indexes less than 1.0 indicate that the
1.2 Values given in SI units are to be regarded as the
test surface is more easily cleanable than the standard of
standard. Inch-pound units are provided for information only.
comparison.
1.3 This standard does not purport to address all of the
3.2 The soiling agent used consists of polyethylene glycol,
safety concerns, if any, associated with its use. It is the
a black dye, and a fluorescent tracer, each of which is readily
responsibility of the user of this standard to establish appro-
water soluble.
priate safety and health practices and determine the applica-
bility of regulatory limitations prior to use.
4. Significance and Use
4.1 This test method was developed to guide the user in
2. Referenced Documents
selecting a finish coating or material that is resistant to soiling
2.1 ASTM Standards:
in a particular application.
C282 Test Method for Acid Resistance of Porcelain Enam-
4.2 The numerical values derived by this test method
els(Citric Acid Spot Test)
enables the user to rank finish coatings and materials in regard
C614 Test Method forAlkali Resistance of Porcelain Enam-
to soil retention or ease of soil removal.
els
5. Apparatus
3. Summary of Test Method
5.1 Motor-Driven Lapping Plate, 203-mm (8-in.) diameter,
3.1 The test method consists of applying an exact amount of
speed 163 r/min.
a fluorescent water-soluble soiling agent to a specimen surface
and then cleaning the surface with a reproducible machine-
5.2 Automatic Polishing Unit, 11-s cycle, adjustable to
wiping technique. The soil remaining on the specimen after
48-mm (1 ⁄8-in.) stroke.
wipingisextractedwithawatersolventandthefluorescenceof
5.3 Hypodermic Syringe, glass, 2-mL capacity, without
the solution measured. A standard reference surface is treated
needle.
5.4 Repeating Pipet, 0.025 mL (25 µl) capacity.
ThistestmethodisunderthejurisdictionofASTMCommitteeB08onMetallic
5.5 Repeating Pipet, 10-mL capacity.
and Inorganic Coatings and is the direct responsibility of Subcommittee B08.12 on
Materials for Porcelain Enamel and Ceramic-Metal Systems.
Current edition approved Nov. 1, 2016. Published November 2016. Originally
ɛ1
approved in 1973. Last previous edition approved in 2011 as C756 – 87 (2011) . Suitable lapping plates are available from Buehler Ltd., 2120 Greenwood St.,
DOI: 10.1520/C0756-87R16. Evanston, IL60204, Struers, Inc., 20102 Progress Drive, Cleveland, OH, 44136; or
For referenced ASTM standards, visit the ASTM website, www.astm.org, or other Metallurgical Supply Sources.
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM An Olsen “S.M.” Automatic Polisher has been found suitable and is available
Standards volume information, refer to the standard’s Document Summary page on under the code name OLPOL from Struers, Inc., 20102 Progress Drive, Cleveland,
the ASTM website. OH 44136.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
C756 − 87 (2016)
5.6 Desiccator approximately 254 mm (10 in.) diameter. 6. Reagents and Materials
5.7 Cleaning Head, brass, 57 mm (2 ⁄4 in.), with worm- 6.1 Cleaning Tissues, approximately 127 by 229 mm (5 by
driven hose clamp for attachment of cleaning tissues (Fig. 1). 9 in.).
Cleaning Head, Brass Soiling Head, Brass
Metric Equivalents
AB C D E F G H
1 5 7 3 5 3 3
in. 2 ⁄4 ⁄8 ⁄8 ⁄16 1 ⁄8 ⁄4 ⁄16
(mm) (57) (16) (22) (5) (25) (16) (19) (5)
FIG. 1 Cleaning and Soiling Heads
5.8 Soiling Head, brass, 25 mm (1 in.) diameter, with 6.2 Potassium Carbonate.
25-mm (1-in.) diameter facing of polytetrafluoroethylene at-
6.3 Polyethylene Glycol, 400.
tached with a water-proof household cement (Fig. 1).
6.4 Uranine, water-soluble, USP.
5.9 Extraction Cell, fitted with a fluorosilicone O-ring, size
5 6.5 Keco Acid Black, B(F101).
1 1
3.2 by 57 mm ( ⁄8 by 2 ⁄4 in.) (Fig. 2).
6.6 Ethyl Alcohol.
5.10 Fluorometer, for measuring the fluorescence of solu-
tions. 6.7 Mild Household Detergent, liquid.
5.11 0.9NeutralDensityFilter,50.8by50.8mm(2by2in.)
7. Test Specimens
glass mounted (transmission 12.5 %).
7.1 The preferred specimen size is 114 mm (4 ⁄2 in.) square,
5.12 Beakers, borosilicate, 100-mL capacity.
but any other size or shape may be used provided it can be
rotated on the lapping wheel and the smaller dimension is
between 102 and 127 mm (4 and 5 in.). Sharp or jagged edges
O-rings must be fluorosilicone polymer; consult Precision Associates, 742 N.
shall be filed or honed to prevent snagging of the cleaning
Washington Ave., Minneapolis, MN 55401; Parker Seal Co., 10567 W. Jefferson
tissues during the mechanical cleaning process.
Blvd., Culver City, CA 90230; & B. W. Rogers (Parker Dis.) 1000 Brookpark Rd.,
Cleveland, OH 44109. Also see other sources in Thomas Register under SEALS:
“O” RINGS.Asuitable device for clamping the cell to a specimen is shown in Fig.
3 and Fig. 5.
6 7
Turner Fluorometer, Model 111 (Turner 111-003) available from Curtin Cel-Fibe Wipes, Type 1745 or equivalent.
Matheson Scientific, Inc., 10727 Tucker St., Beltsville, MD 20705, Sequoia-Turner Uranine is the sodium salt of fluorescein, C H O Na .
20 10 5 2
Dial Model 111, Fisher Scientific Co., 711 Forbes Ave., Pittsburg, PA 15219, and Awater-soluble fabric dye used principally for nylon, silk, and wool; available
other principal cities for both. from Keystone Aniline and Chemical Co., 321 N. Loomis, Chicago, IL 60607.
C756 − 87 (2016)
Metric Equivalents
AB C D E F G H I
1 1 1 1 1 5 1 7 1
in. ⁄16 ⁄8 ⁄64 2 ⁄2 1 ⁄4 ⁄8 ⁄16 1 ⁄8 2 ⁄8
(mm.) (1.6) (3.2) (0.4) (64) (32) (16) (1.6) (47) (54)
All surfaces to be plated with bright nickel.
FIG. 2 Brass Extraction Cell
7.2 Twelvespecimensarerequiredtoevaluatethecleanabil- dissolved in the glycol. The black dye which obscures all else
ity index, that is, six of the candidate surface, and six of a shall be added last and thoroughly mixed in the blender. This
porcelain enamel standard reference surface for cleanability. soiling agent shall be stored in a tightly stoppered glass bottle
Porcelain enamel specimens are not damaged by the cleanabil- at least overnight before use.
ity test and may be cleaned and reused many times. Specimens
9. Procedure
have been reused as many as 50 times without damage or solid
buildup.
9.1 Specimen Pretreatment—Scrub the specimens with a
cellulose sponge wet with a 1 % solution of a mild household
NOTE 1—The porcelain enamel covercoat used to coat the standard
detergent at room temperature. Rinse in turn with tap water,
reference surface shall have the following characteristics: Acid Resis-
tance:AA(Test Method C282)Alkali Resistance: Maximum 1.55 mg/cm distilled water, and ethyl alcohol, and allow to dry in a
wt. loss (Test Method C614).
near-vertical position at room temperature. Store the washed
and dried specimens overnight in a desiccator charged with a
8. Preparation of Standard Soil
saturated solution of potassium carbonate.
8.1 The soiling agent shall consist of the following:
9.2 Conditioning of Cleaning Tissues—Cut a supply of
Ingredient Weight %
tissues ample for use in specimen cleaning treatment in the
Polyethylene glycol 98
following paragraph into approximately 102-mm (4-in.)
Keco Acid Black B 1
Uranine, water-soluble 1
squares and store overnight, before use, in a desiccator charged
8.2 The uranine shall be added to the polyethylene glycol in with a saturated solution of potassium carbonate (relative
humidity approximately 45 %). Allow the tissues to remain in
food blender and mixed by alternate periods of mixing and
standing until the crystalline uranine appears to be completely the desiccator until just prior to use.
C756 − 87 (2016)
Metric Equivalents
AB C D E F G H I J K L M N
1 1 3 1 7 5 1 1 1 5 5
in. ⁄16 2 ⁄4 1 ⁄8 ⁄4 1 ⁄8 ⁄16 56 1 ⁄4 3 ⁄4 ⁄4 4 ⁄8 4 ⁄8 5
(mm) (1.6) (64) (35) (6.4) (47) (8) (127) (152) (32) (83) (6.4) (117) (117) (127)
FIG. 3 Device for Clamping Extraction Cell to Specimen
9.3 Soiling and Cleaning Treatments: 22 s (so that it will stop as well as start at the center of the
9.3.1 Lay out six specimens face up on a table. Homogenize specimen). Remove the cleaning head without sliding motion.
thesoilingagentbyup-endingseveraltimesbeforeuse.Fillthe
Repeat the cleaning operation with the second tissue-covered
hypodermic syringe with no needle attached with the soiling head,usingthesameamountofdistilledwaterandforthesame
agent by withdrawing the plunger. Expel this charge of soil
22-s period.
back into the soil bottle. Then fill the syringe again. Wipe the
9.3.3 Store the first soiled and cleaned specimen in a near
tipofthesyringewithacleaningtissueandexpelseveraldrops
vertical position in a rack while applying exactly the same
into the soil bottle. Then, without rewiping the tip, hold the
series of soiling and cleaning treatments to the five remaining
syringe vertically over a specimen and discharge one drop near
specimens.
the center of each of the six specimens. Center the first
9.4 Water Extraction of the Soil Retained—Remove the
specimen on the lapping wheel and hold it in place by means
small, often nonvisible, amounts of soil from the central
of adhesive tape across the specimen corners. Place the
portion of the soiled and cleaned specimens with 10 mL of
polytetrafluoroethylene-faced soiling head on the soil, and
distilled water in the O-ring sealed extraction cell by the
engage the spindle (Fig. 4) of the polishing unit. Operate the
following sequence of operations within 30 min after soiling;
lapping wheel and the polishing unit for 1 min to distribute the
place the first soiled and cleaned specimen, face up, in the
soil over the central portion of the specimen (Fig. 5). Remove
center of the cell clamping frame. Place a clean and dry
the soiling head and clean it with tissue for reuse. Adjust the
spindle so that it rests over the center of the soil spot. Prepare extraction cell (Fig. 2) on the center of the specimen so that the
O-ring defines the area to be extracted (Fig. 5). Clamp the cell
twocleaningheads57mm(2 ⁄4in.)diameter)bycoveringwith
fourthicknessesofcleaningtissuesclampedsmoothlyinplace. intheframewithalightpressurefromthewingnuts;introduce
10 mL of distilled water with the 10-mL repeating pipet, swirl
With the repeating pipet expel exactly 0.021 mL of distilled
water at the center of the tissue on the first cleaning head. the water in the cell momentarily and let stand for 3 min, give
the solution in the cell another swirl and pour out into a clean
9.3.2 Immediately place the cleaning head with tissue side
againstthesoiledspecimen,engagethespindle,andoperatefor and dry 100 mL beaker; transfer a portion of the extract to a
C756 − 87 (2016)
Metric Equivalents
AB C
1 1
in. 10 ⁄2 ⁄4
(mm.) (254) (13) (6.4)
FIG. 4 Spindle for Polisher
FIG. 5 Equipment Used in Soiling and Cleaning Specimens
clean, dry cuvette and place the cuvette in a rack until the other 9.5 MeasurementofFluorescence—Operate the fluorometer
five extracts are ready for measurement in the fluorometer. according to the manufacturer’s instructions. Measure and
C756 − 87 (2016)
record the fluorescence of a distilled water blank. Measure and 10. Calculation of a Cleanability Index
record in turn the fluorescence of the solutions extracted from
10.1 Subtract the measured fluorescence value for the dis-
the specimens.
tilled water blank from the measured fluorescence value for
each of the six test surfaces and the six standard reference
NOTE 2—If concentrated solutions give off-scale readings, a 0.9
surfaces. This will result in corrected fluorescence values for
neutral-density filter should be inserted between the fluorescing solution
the six test surfaces and for the six standard reference surfaces.
and the photomultiplier. This filter transmits only 12.5 % of the light
emitted by the solution, reducing the fluroescence readings and bringing
10.2 Calculate the average of the corrected fluorescence
them on scale. Redetermine the blank reading with the filter in place and
values for the six test surfaces and for the six standard
multiply the reduced reading by 8.0 which is 1 divided by the 12.5 %
reference surfaces.
transmission of the neutral density filter.
10.3 Calculate the coefficient of variation of the corrected
9.6 Standard Reference Surface—Apply the test procedure
fluorescence values for the six test surfaces and for the six
outlined in 7.1 through 7.5 to the Standard Reference Surfaces
standard reference surfaces.
at least once during each testing day to obtain the average
10.4 Repeat the cleanability determinations on all six speci-
fluorescence of solutions extracted from these specimens.
mens (either the test specimens or the six standard reference
specimens) if the coefficient of variation is greater than 20 %.
9.7 Preferred Methods of Equipment Cleaning:
10.5 The cleanability index is calculated as follows:
9.7.1 The successful use of the fluorimetric analytical tech-
niques employed in this procedure demands that a scrupulous
CI 5 Ft/Fr (1)
level of cleanliness be maintained throughout. An oily thumb-
where:
print on the glass cuvette containing the solution to be
CI = the cleanability index of the surface being tested,
measured may be more fluorescent than the unknown.
Ft = the average corrected fluorescence of the test surfaces
9.7.2 Wash the glass beakers
...
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: C756 − 87 (Reapproved 2011) C756 − 87 (Reapproved 2016)
Standard Test Method for
Cleanability of Surface Finishes
This standard is issued under the fixed designation C756; 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 provides a procedure to quantify the cleanability of acid-resistant porcelain enamel using
a fluorescent water-soluble soil in agent, a reproducible machine-wiping technique, and a means of
measuring the amount of residual soil by fluorescence.
1. Scope
1.1 This test method covers the numerical evaluation of the ease or difficulty of cleaning soiled surface finishes. This test method
is applicable to all surface finishes not affected by water.
1.2 Values given in SI units are to be regarded as the standard. Inch-pound units are provided for information only.
1.3 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:
C282 Test Method for Acid Resistance of Porcelain Enamels(Citric Acid Spot Test)
C614 Test Method for Alkali Resistance of Porcelain Enamels
3. Summary of Test Method
3.1 The test method consists of applying an exact amount of a fluorescent water-soluble soiling agent to a specimen surface and
then cleaning the surface with a reproducible machine-wiping technique. The soil remaining on the specimen after wiping is
extracted with a water solvent and the fluorescence of the solution measured. A standard reference surface is treated in a similar
manner. The cleanability index of the surface under test is expressed as the ratio of the fluorescence of the solutions extracted from
the test surface and from the standard reference surface. Cleanability indexes greater than 1.0 indicate that the test surface is more
difficult to clean than the standard reference surface, while indexes less than 1.0 indicate that the test surface is more easily
cleanable than the standard of comparison.
3.2 The soiling agent used consists of polyethylene glycol, a black dye, and a fluorescent tracer, each of which is readily water
soluble.
4. Significance and Use
4.1 This test method was developed to guide the user in selecting a finish coating or material that is resistant to soiling in a
particular application.
4.2 The numerical values derived by this test method enables the user to rank finish coatings and materials in regard to soil
retention or ease of soil removal.
This test method is under the jurisdiction of ASTM Committee B08 on Metallic and Inorganic Coatings and is 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 1973. Last previous edition approved in 20062011 as
ɛ1
C756 – 87 (2006).(2011) . DOI: 10.1520/C0756-87R11E01.10.1520/C0756-87R16.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at service@astm.org. 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
C756 − 87 (2016)
5. Apparatus
5.1 Motor-Driven Lapping Plate, 203-mm (8-in.) diameter, speed 163 r/min.
5.2 Automatic Polishing Unit, 11-s cycle, adjustable to 48-mm (1 ⁄8-in.) stroke.
5.3 Hypodermic Syringe, glass, 2-mL capacity, without needle.
5.4 Repeating Pipet, 0.025 mL (25 μl) capacity.
5.5 Repeating Pipet, 10-mL capacity.
5.6 Desiccator approximately 254 mm (10 in.) diameter.
5.7 Cleaning Head, brass, 57 mm (2 ⁄4 in.), with worm-driven hose clamp for attachment of cleaning tissues (Fig. 1).
Cleaning Head, Brass Soiling Head, Brass
Metric Equivalents
A B C D E F G H
1 5 7 3 5 3 3
in. 2 ⁄4 ⁄8 ⁄8 ⁄16 1 ⁄8 ⁄4 ⁄16
(mm) (57) (16) (22) (5) (25) (16) (19) (5)
FIG. 1 Cleaning and Soiling Heads
5.8 Soiling Head, brass, 25 mm (1 in.) diameter, with 25-mm (1-in.) diameter facing of polytetrafluoroethylene attached with
a water-proof household cement (Fig. 1).
1 1
5.9 Extraction Cell, fitted with a fluorosilicone O-ring, size 3.2 by 57 mm ( ⁄8 by 2 ⁄4 in.) (Fig. 2).
5.10 Fluorometer, for measuring the fluorescence of solutions.
5.11 0.9 Neutral Density Filter, 50.8 by 50.8 mm (2 by 2 in.) glass mounted (transmission 12.5 %).
5.12 Beakers, borosilicate, 100-mL capacity.
Suitable lapping plates are available from Buehler Ltd., 2120 Greenwood St., Evanston, IL 60204, Struers, Inc., 20102 Progress Drive, Cleveland, OH, 44136; or other
Metallurgical Supply Sources.
An Olsen “S.M.” Automatic Polisher has been found suitable and is available under the code name OLPOL from Struers, Inc., 20102 Progress Drive, Cleveland, OH
44136.
O-rings must be fluorosilicone polymer; consult Precision Associates, 742 N. Washington Ave., Minneapolis, MN 55401; Parker Seal Co., 10567 W. Jefferson Blvd.,
Culver City, CA 90230; & B. W. Rogers (Parker Dis.) 1000 Brookpark Rd., Cleveland, OH 44109. Also see other sources in Thomas Register under SEALS: “O” RINGS.
A suitable device for clamping the cell to a specimen is shown in Fig. 3 and Fig. 5.
Turner Fluorometer, Model 111 (Turner 111-003) available from Curtin Matheson Scientific, Inc., 10727 Tucker St., Beltsville, MD 20705, Sequoia-Turner Dial Model
111, Fisher Scientific Co., 711 Forbes Ave., Pittsburg, PA 15219, and other principal cities for both.
C756 − 87 (2016)
Metric Equivalents
A B C D E F G H I
1 1 1 1 1 5 1 7 1
in. ⁄16 ⁄8 ⁄64 2 ⁄2 1 ⁄4 ⁄8 ⁄16 1 ⁄8 2 ⁄8
(mm.) (1.6) (3.2) (0.4) (64) (32) (16) (1.6) (47) (54)
All surfaces to be plated with bright nickel.
FIG. 2 Brass Extraction Cell
6. Reagents and Materials
6.1 Cleaning Tissues, approximately 127 by 229 mm (5 by 9 in.).
6.2 Potassium Carbonate.
6.3 Polyethylene Glycol, 400.
6.4 Uranine, water-soluble, USP.
6.5 Keco Acid Black, B(F101).
6.6 Ethyl Alcohol.
6.7 Mild Household Detergent, liquid.
7. Test Specimens
7.1 The preferred specimen size is 114 mm (4 ⁄2 in.) square, but any other size or shape may be used provided it can be rotated
on the lapping wheel and the smaller dimension is between 102 and 127 mm (4 and 5 in.). Sharp or jagged edges shall be filed
or honed to prevent snagging of the cleaning tissues during the mechanical cleaning process.
7.2 Twelve specimens are required to evaluate the cleanability index, that is, six of the candidate surface, and six of a porcelain
enamel standard reference surface for cleanability. Porcelain enamel specimens are not damaged by the cleanability test and may
be cleaned and reused many times. Specimens have been reused as many as 50 times without damage or solid buildup.
Cel-Fibe Wipes, Type 1745 or equivalent.
Uranine is the sodium salt of fluorescein, C H O Na .
20 10 5 2
A water-soluble fabric dye used principally for nylon, silk, and wool; available from Keystone Aniline and Chemical Co., 321 N. Loomis, Chicago, IL 60607.
C756 − 87 (2016)
Metric Equivalents
A B C D E F G H I J K L M N
1 1 3 1 7 5 1 1 1 5 5
in. ⁄16 2 ⁄4 1 ⁄8 ⁄4 1 ⁄8 ⁄16 5 6 1 ⁄4 3 ⁄4 ⁄4 4 ⁄8 4 ⁄8 5
(mm) (1.6) (64) (35) (6.4) (47) (8) (127) (152) (32) (83) (6.4) (117) (117) (127)
FIG. 3 Device for Clamping Extraction Cell to Specimen
NOTE 1—The porcelain enamel covercoat used to coat the standard reference surface shall have the following characteristics: Acid Resistance: AA (Test
Method C282) Alkali Resistance: Maximum 1.55 mg/cm wt. loss (Test Method C614).
8. Preparation of Standard Soil
8.1 The soiling agent shall consist of the following:
Ingredient Weight %
Polyethylene glycol 98
Keco Acid Black B 1
Uranine, water-soluble 1
8.2 The uranine shall be added to the polyethylene glycol in food blender and mixed by alternate periods of mixing and standing
until the crystalline uranine appears to be completely dissolved in the glycol. The black dye which obscures all else shall be added
last and thoroughly mixed in the blender. This soiling agent shall be stored in a tightly stoppered glass bottle at least overnight
before use.
9. Procedure
9.1 Specimen Pretreatment—Scrub the specimens with a cellulose sponge wet with a 1 % solution of a mild household detergent
at room temperature. Rinse in turn with tap water, distilled water, and ethyl alcohol, and allow to dry in a near-vertical position
at room temperature. Store the washed and dried specimens overnight in a desiccator charged with a saturated solution of
potassium carbonate.
9.2 Conditioning of Cleaning Tissues—Cut a supply of tissues ample for use in specimen cleaning treatment in the following
paragraph into approximately 102-mm (4-in.) squares and store overnight, before use, in a desiccator charged with a saturated
solution of potassium carbonate (relative humidity approximately 45 %). Allow the tissues to remain in the desiccator until just
prior to use.
C756 − 87 (2016)
9.3 Soiling and Cleaning Treatments:
9.3.1 Lay out six specimens face up on a table. Homogenize the soiling agent by up-ending several times before use. Fill the
hypodermic syringe with no needle attached with the soiling agent by withdrawing the plunger. Expel this charge of soil back into
the soil bottle. Then fill the syringe again. Wipe the tip of the syringe with a cleaning tissue and expel several drops into the soil
bottle. Then, without rewiping the tip, hold the syringe vertically over a specimen and discharge one drop near the center of each
of the six specimens. Center the first specimen on the lapping wheel and hold it in place by means of adhesive tape across the
specimen corners. Place the polytetrafluoroethylene-faced soiling head on the soil, and engage the spindle (Fig. 4) of the polishing
unit. Operate the lapping wheel and the polishing unit for 1 min to distribute the soil over the central portion of the specimen (Fig.
5). Remove the soiling head and clean it with tissue for reuse. Adjust the spindle so that it rests over the center of the soil spot.
Prepare two cleaning heads 57 mm (2 ⁄4 in.) diameter) by covering with four thicknesses of cleaning tissues clamped smoothly in
place. With the repeating pipet expel exactly 0.021 mL of distilled water at the center of the tissue on the first cleaning head.
9.3.2 Immediately place the cleaning head with tissue side against the soiled specimen, engage the spindle, and operate for 22
s (so that it will stop as well as start at the center of the specimen). Remove the cleaning head without sliding motion. Repeat the
cleaning operation with the second tissue-covered head, using the same amount of distilled water and for the same 22-s period.
9.3.3 Store the first soiled and cleaned specimen in a near vertical position in a rack while applying exactly the same series of
soiling and cleaning treatments to the five remaining specimens.
9.4 Water Extraction of the Soil Retained—Remove the small, often nonvisible, amounts of soil from the central portion of the
soiled and cleaned specimens with 10 mL of distilled water in the O-ring sealed extraction cell by the following sequence of
operations within 30 min after soiling; place the first soiled and cleaned specimen, face up, in the center of the cell clamping frame.
Place a clean and dry extraction cell (Fig. 2) on the center of the specimen so that the O-ring defines the area to be extracted (Fig.
5). Clamp the cell in the frame with a light pressure from the wing nuts; introduce 10 mL of distilled water with the 10-mL
repeating pipet, swirl the water in the cell momentarily and let stand for 3 min, give the solution in the cell another swirl and pour
out into a clean and dry 100 mL beaker; transfer a portion of the extract to a clean, dry cuvette and place the cuvette in a rack until
the other five extracts are ready for measurement in the fluorometer.
9.5 Measurement of Fluorescence—Operate the fluorometer according to the manufacturer’s instructions. Measure and record
the fluorescence of a distilled water blank. Measure and record in turn the fluorescence of the solutions extracted from the
specimens.
Metric Equivalents
A B C
1 1
in. 10 ⁄2 ⁄4
(mm.) (254) (13) (6.4)
FIG. 4 Spindle for Polisher
C756 − 87 (2016)
FIG. 5 Equipment Used in Soiling and Cleaning Specimens
NOTE 2—If concentrated solutions give off-scale readings, a 0.9 neutral-density filter should be inserted between the fluorescing solution and the
photomultiplier. This filter transmits only 12.5 % of the light emitted by the solution, reducing the fluroescence readings and bringing them on scale.
Redetermine the blank reading with the filter in place and multiply the reduced reading by 8.0 which is 1 divided by the 12.5 % transmission of the neutral
density filter.
9.6 Standard Reference Surface—Apply the test procedure outlined in 7.1 through 7.5 to the Standard Reference Surfaces at
least once during each testing day to obtain the average fluorescence of solutions extracted from these specimens.
9.7 Preferred Methods of Equipment Cleaning:
9.7.1 The successful use of the fluorimetric analytical techniques employed in this procedure demands that a scrupulous level
of cleanliness be maintained throughout. An oily thumb-print on the glass cuvette containing the solution to be measured may be
more fluorescent than the unknown.
9.7.2 Wash the glass beakers and the extraction cells before and after use by brushing in a warm detergent solution; rinse
copiously with flowing tap water and then with distilled water. The glass beakers may be oven dried. The extraction cells, without
O-ring removal, may be wiped dry with clean tissue. Clean the syringe used for dispensing uniform amounts of soil on the
specimens immediately following use with tap water, distilled water and alcohol, and dry the parts with tissue. Give the gla
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