ASTM D88/D88M-07(2019)e1

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.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
´1
Designation: D88/D88M − 07 (Reapproved 2019) American Association State
Highway and Transportation Officials Standard
AASHTO No: T72
Method 304—Federal Test
Method Standard No. 791b
Replaces Method 4285 of Federal Test
Method Standard No. 141A
Standard Test Method for
Saybolt Viscosity
This standard is issued under the fixed designation D88/D88M; 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.
This standard has been approved for use by agencies of the U.S. Department of Defense.
ε NOTE—Units information was editorially corrected in May 2019.
1. Scope 2. Referenced Documents
1.1 This test method covers the empirical procedures for 2.1 ASTM Standards:
determining the Saybolt Universal or Saybolt Furol viscosities D93 Test Methods for Flash Point by Pensky-Martens
of petroleum products at specified temperatures between 21 Closed Cup Tester
and 99°C [70 and 210°F]. A special procedure for waxy D117 Guide for Sampling, Test Methods, and Specifications
products is indicated. for Electrical Insulating Liquids
D140/D140M Practice for Sampling Asphalt Materials
NOTE 1—Test Methods D445 and D2170/D2170M are preferred for the
D244 Test Methods and Practices for Emulsified Asphalts
determination of kinematic viscosity. They require smaller samples and
D445 Test Method for Kinematic Viscosity of Transparent
less time, and provide greater accuracy. Kinematic viscosities may be
converted to Saybolt viscosities by use of the tables in Practice D2161. It
and Opaque Liquids (and Calculation of Dynamic Viscos-
is recommended that viscosity indexes be calculated from kinematic rather
ity)
than Saybolt viscosities.
D2161 Practice for Conversion of Kinematic Viscosity to
1.2 The values stated in either SI units or inch-pound units
Saybolt Universal Viscosity or to Saybolt Furol Viscosity
are to be regarded separately as standard. The values stated in
D2170/D2170M Test Method for Kinematic Viscosity of
each system are not necessarily exact equivalents; therefore, to
Asphalts
ensure conformance with the standard, each system shall be
D4057 Practice for Manual Sampling of Petroleum and
used independently of the other, and values from the two
Petroleum Products
systems shall not be combined.
D4177 Practice for Automatic Sampling of Petroleum and
Petroleum Products
1.3 This standard does not purport to address all of the
E1 Specification for ASTM Liquid-in-Glass Thermometers
safety concerns, if any, associated with its use. It is the
E11 Specification for Woven Wire Test Sieve Cloth and Test
responsibility of the user of this standard to establish appro-
Sieves
priate safety, health, and environmental practices and deter-
E102/E102M Test Method for Saybolt Furol Viscosity of
mine the applicability of regulatory limitations prior to use.
Bituminous Materials at High Temperatures
1.4 This international standard was developed in accor-
dance with internationally recognized principles on standard-
3. Terminology
ization established in the Decision on Principles for the
Development of International Standards, Guides and Recom-
3.1 Definitions:
mendations issued by the World Trade Organization Technical
3.1.1 Furol—an acronym of “Fuel and road oils.”
Barriers to Trade (TBT) Committee.
3.1.2 Saybolt Furol viscosity—the corrected efflux time in
seconds of 60 mL of sample flowing through a calibrated Furol
orifice under specified conditions. The viscosity value is
This test method is under the jurisdiction of ASTM Committee D08 on Roofing
and Waterproofing and is the direct responsibility of Subcommittee D08.05 on
Solvent-Bearing Bituminous Compounds for Roofing and Waterproofing.
Current edition approved May 1, 2019. Published June 2019. Originally For referenced ASTM standards, visit the ASTM website, www.astm.org, or
approved in 1921. In 1923, combined with former Methods D47. Last previous contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
edition approved in 2013 as D88 – 07 (2013). DOI: 10.1520/D0088_D0088M- Standards volume information, refer to the standard’s Document Summary page on
07R19E01. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
´1
D88/D88M − 07 (2019)
reported in Saybolt Furol seconds, abbreviated SFS, at a 5.3 The Saybolt Furol viscosity is approximately one tenth
specified temperature. the Saybolt Universal viscosity, and is recommended for
characterization of petroleum products such as fuel oils and
3.1.3 Saybolt Universal viscosity—the corrected efflux time
other residual materials having Saybolt Universal viscosities
in seconds of 60 mL of sample flowing through a calibrated
greater than 1000 s.
Universal orifice under specified conditions. The viscosity
value is reported in Saybolt Universal seconds, abbreviated 5.4 Determination of the Saybolt Furol viscosity of bitumi-
SUS, at a specified temperature. nous materials at higher temperatures is covered by Test
Method E102/E102M.
4. Summary of Test Method
6. Apparatus
4.1 The efflux time in seconds of 60 mL of sample, flowing
6.1 Saybolt Viscometer and Bath, as shown in Fig. 1 and
through a calibrated orifice, is measured under carefully
described in Annex A1.
controlled conditions. This time is corrected by an orifice
6.2 Withdrawal Tube, as shown in Fig. 2.
factor and reported as the viscosity of the sample at that
temperature.
6.3 Thermometer Support, as shown in Fig. 3.
6.4 Saybolt Viscosity Thermometers , as listed in Table 1, for
5. Significance and Use
reading the temperature of the sample. Each thermometer shall
5.1 This test method is useful in characterizing certain
conform to the requirements listed in Specification E1 for that
petroleum products, as one element in establishing uniformity
ASTM Thermometer Number.
of shipments and sources of supply.
6.5 Bath Thermometers—Saybolt Viscosity thermometers,
5.2 See Guide D117 for applicability to mineral oils used as or any other temperature-indicating means of equivalent accu-
electrical insulating oils. racy.
NOTE 1—All dimensions are in millimetres (inches).
FIG. 1 Saybolt Viscometer with Universal and Furol Orifice
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D88/D88M − 07 (2019)
TABLE 1 ASTM Saybolt Viscosity Thermometers
Standard Test ASTM
Thermometer
Temperature Thermometer
Range °C [°F] Subdivisions, °C [°F]
°C [°F] No.
21.1 [70] 17C [17F] 19 to 27 0.1 [0.2]
[66 to 80]
25.0 [77] 17C [17F] 19 to 27 0.1 [0.2]
[66 to 80]
37.8 [100] 18C [18F] 34 to 42 0.1 [0.2]
[94 to 108]
50.0 [122] 19C [19F] 49 to 57 0.1 [0.2]
[120 to 134]
54.4 [130] 19C [19F] 49 to 57 0.1 [0.2]
[120 to 134]
60.0 [140] 20C [20F] 57 to 65 0.1 [0.2]
[134 to 148]
82.2 [180] 21C [21F] 79 to 87 0.1 [0.2]
[174 to 188]
98.9 [210] 22C [22F] 95 to 103 0.1 [0.2]
[204 to 218]
6.6 Filter Funnel, as shown in Fig. 4, equipped with
interchangeable 150-µm [No. 100] and 75-µm [No. 200]
wire-cloth inserts meeting the requirements of Specification
E11 with respect to the wire cloth.
6.7 Receiving Flask, as shown in Fig. 5.
6.8 Timer, graduated in tenths of a second, and accurate to
within 0.1 % when tested over a 60-min interval. Electric
timers are acceptable if operated on a controlled frequency
circuit.
7. Sampling
7.1 Sample the material in accordance with Practices D140/
D140M, D4057, or D4177, as appropriate.
8. Preparation of Apparatus
8.1 Use a Universal orifice or tip for lubricants and distil-
NOTE 1—All dimensions are in millimetres (inches).
lates with efflux times greater than 32 s to give the desired
FIG. 2 Withdrawal Tube for Use with Saybolt Viscometer
accuracy. Liquids with efflux times greater than 1000 s are not
conveniently tested with this orifice.
8.2 Use a Furol orifice or tip for residual materials with
efflux times greater than 25 s to give the desired accuracy. See
also 5.3.
8.3 Clean the viscometer thoroughly with an appropriate
solvent of low toxicity; then remove all solvent from the
viscometer and its gallery. Clean the receiving flask in the same
manner.
NOTE 2—The plunger commonly supplied with the viscometer should
never be used for cleaning; its use might damage the overflow rim and
walls of the viscometer.
8.4 Set up the viscometer and bath in an area where they
will not be exposed to drafts or rapid changes in air
temperature, and dust or vapors that might contaminate a
sample.
8.5 Place the receiving flask (Fig. 5) beneath the viscometer
NOTE 1—All dimensions are in millimetres (inches). so that the graduation mark on the flask is from 100 to 130 mm
FIG. 3 Thermometer Support
[4 to 5 in.] below the bottom of the viscometer tube, and so that
the stream of oil will just strike the neck of the flask.
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D88/D88M − 07 (2019)
NOTE 1—All dimensions are in millimetres (inches).
FIG. 4 Filter Funnel for Use with Saybolt Viscometer
8.6 Fill the bath to at least 6 mm [ ⁄4 in.] above the overflow actual temperature. However room temperatures up to 38°C
rim of the viscometer with an appropriate bath medium [100°F] will not introduce errors in excess of 1 %.
selected from Table 2.
9. Calibration and Standardization
8.7 Provide adequate stirring and thermal control for the
bath so that the temperature of a test sample in the viscometer
9.1 Calibrate the Saybolt Universal viscometer at periodic
will not vary more than 60.03°C [60.05°F] after reaching the
intervals by measuring the efflux time at 37.8°C [100°F] of an
selected test temperature.
appropriate viscosity oil standard, following the procedure
given in Section 10. See Annex A2 for viscosity oil standards
8.8 Do not make viscosity measurements at temperatures
available.
below the dew point of the room’s atmosphere.
8.9 For calibration and referee tests, keep the room tem- 9.2 The efflux time of the viscosity oil standard shall equal
perature between 20 and 30°C [68 and 86°F], and record the the certified Saybolt viscosity value. If the efflux time differs
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D88/D88M − 07 (2019)
10.3 If the selected test temperature is above room
temperature, the test may be expedited by preheating the
sampl
...

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: D88 − 07 (Reapproved 2013) D88/D88M − 07 (Reapproved 2019)American Association State
Highway and Transportation Officials Standard
AASHTO No: T72
Method 304—Federal Test
Method Standard No. 791b
Replaces Method 4285 of Federal Test
Method Standard No. 141A
Standard Test Method for
Saybolt Viscosity
This standard is issued under the fixed designation D88;D88/D88M; 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.
This standard has been approved for use by agencies of the U.S. Department of Defense.
ε NOTE—Units information was editorially corrected in May 2019.
1. Scope
1.1 This test method covers the empirical procedures for determining the Saybolt Universal or Saybolt Furol viscosities of
petroleum products at specified temperatures between 21 and 99°C (70[70 and 210°F).210°F]. A special procedure for waxy
products is indicated.
NOTE 1—Test Methods D445 and D2170D2170/D2170M are preferred for the determination of kinematic viscosity. They require smaller samples and
less time, and provide greater accuracy. Kinematic viscosities may be converted to Saybolt viscosities by use of the tables in Practice D2161. It is
recommended that viscosity indexes be calculated from kinematic rather than Saybolt viscosities.
1.2 The values stated in either SI units or inch-pound units are to be regarded separately as the standard. The values givenstated
in parentheses are for information only.each system are not necessarily exact equivalents; therefore, to ensure conformance with
the standard, each system shall be used independently of the other, and values from the two systems shall not be combined.
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 safety, health, and healthenvironmental practices and determine the
applicability of regulatory limitations prior to use.
1.4 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 ASTM Standards:
D93 Test Methods for Flash Point by Pensky-Martens Closed Cup Tester
D117 Guide for Sampling, Test Methods, and Specifications for Electrical Insulating Liquids
D140D140/D140M Practice for Sampling Asphalt Materials
D244 Test Methods and Practices for Emulsified Asphalts
D445 Test Method for Kinematic Viscosity of Transparent and Opaque Liquids (and Calculation of Dynamic Viscosity)
D2161 Practice for Conversion of Kinematic Viscosity to Saybolt Universal Viscosity or to Saybolt Furol Viscosity
D2170D2170/D2170M Test Method for Kinematic Viscosity of Asphalts
D4057 Practice for Manual Sampling of Petroleum and Petroleum Products
D4177 Practice for Automatic Sampling of Petroleum and Petroleum Products
E1 Specification for ASTM Liquid-in-Glass Thermometers
E11 Specification for Woven Wire Test Sieve Cloth and Test Sieves
E102E102/E102M Test Method for Saybolt Furol Viscosity of Bituminous Materials at High Temperatures
This test method is under the jurisdiction of ASTM Committee D08 on Roofing and Waterproofing and is the direct responsibility of Subcommittee D08.05 on
Solvent-Bearing Bituminous Compounds for Roofing and Waterproofing.
Current edition approved May 1, 2013May 1, 2019. Published May 2013June 2019. Originally approved in 1921. In 1923, combined with former Methods D47. Last
previous edition approved in 20072013 as D88 – 07.D88 – 07 (2013). DOI: 10.1520/D0088-07R13.10.1520/D0088_D0088M-07R19E01.
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
´1
D88/D88M − 07 (2019)
3. Terminology
3.1 Definitions:
3.1.1 Furol—an acronym of “Fuel and road oils.”
3.1.2 Saybolt Furol viscosity—the corrected efflux time in seconds of 60 mL of sample flowing through a calibrated Furol orifice
under specified conditions. The viscosity value is reported in Saybolt Furol seconds, abbreviated SFS, at a specified temperature.
3.1.3 Saybolt Universal viscosity—the corrected efflux time in seconds of 60 mL of sample flowing through a calibrated
Universal orifice under specified conditions. The viscosity value is reported in Saybolt Universal seconds, abbreviated SUS, at a
specified temperature.
4. Summary of Test Method
4.1 The efflux time in seconds of 60 mL of sample, flowing through a calibrated orifice, is measured under carefully controlled
conditions. This time is corrected by an orifice factor and reported as the viscosity of the sample at that temperature.
5. Significance and Use
5.1 This test method is useful in characterizing certain petroleum products, as one element in establishing uniformity of
shipments and sources of supply.
5.2 See Guide D117 for applicability to mineral oils used as electrical insulating oils.
5.3 The Saybolt Furol viscosity is approximately one tenth the Saybolt Universal viscosity, and is recommended for
characterization of petroleum products such as fuel oils and other residual materials having Saybolt Universal viscosities greater
than 1000 s.
5.4 Determination of the Saybolt Furol viscosity of bituminous materials at higher temperatures is covered by Test Method
E102E102/E102M.
6. Apparatus
6.1 Saybolt Viscometer and Bath, as shown in Fig. 1 and described in Annex A1.
6.2 Withdrawal Tube, as shown in Fig. 2.
6.3 Thermometer Support, as shown in Fig. 3.
6.4 Saybolt Viscosity Thermometers , as listed in Table 1, for reading the temperature of the sample. Each thermometer shall
conform to the requirements listed in Specification E1 for that ASTM Thermometer Number.
6.5 Bath Thermometers—Saybolt Viscosity thermometers, or any other temperature-indicating means of equivalent accuracy.
6.6 Filter Funnel, as shown in Fig. 4, equipped with interchangeable 150-μm (No. 100)[No. 100] and 75-μm (No. 200)[No. 200]
wire-cloth inserts meeting the requirements of Specification E11 with respect to the wire cloth.
6.7 Receiving Flask, as shown in Fig. 5.
6.8 Timer, graduated in tenths of a second, and accurate to within 0.1 % when tested over a 60-min interval. Electric timers are
acceptable if operated on a controlled frequency circuit.
7. Sampling
7.1 Sample the material in accordance with Practices D140D140/D140M, D4057, or D4177, as appropriate.
8. Preparation of Apparatus
8.1 Use a Universal orifice or tip for lubricants and distillates with efflux times greater than 32 s to give the desired accuracy.
Liquids with efflux times greater than 1000 s are not conveniently tested with this orifice.
8.2 Use a Furol orifice or tip for residual materials with efflux times greater than 25 s to give the desired accuracy. See also 5.3.
8.3 Clean the viscometer thoroughly with an appropriate solvent of low toxicity; then remove all solvent from the viscometer
and its gallery. Clean the receiving flask in the same manner.
NOTE 2—The plunger commonly supplied with the viscometer should never be used for cleaning; its use might damage the overflow rim and walls
of the viscometer.
8.4 Set up the viscometer and bath in an area where they will not be exposed to drafts or rapid changes in air temperature, and
dust or vapors that might contaminate a sample.
8.5 Place the receiving flask (Fig. 5) beneath the viscometer so that the graduation mark on the flask is from 100 to 130 mm
(4[4 to 5 in.)in.] below the bottom of the viscometer tube, and so that the stream of oil will just strike the neck of the flask.
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NOTE 1—All dimensions are in millimetres (inches).
FIG. 1 Saybolt Viscometer with Universal and Furol Orifice
8.6 Fill the bath to at least 6 mm ([ ⁄4 in.)in.] above the overflow rim of the viscometer with an appropriate bath medium selected
from Table 2.
8.7 Provide adequate stirring and thermal control for the bath so that the temperature of a test sample in the viscometer will not
vary more than 60.03°C (60.05°F)[60.05°F] after reaching the selected test temperature.
8.8 Do not make viscosity measurements at temperatures below the dew point of the room’s atmosphere.
8.9 For calibration and referee tests, keep the room temperature between 20 and 30°C (68[68 and 86°F),86°F], and record the
actual temperature. However room temperatures up to 38°C (100°F)[100°F] will not introduce errors in excess of 1 %.
9. Calibration and Standardization
9.1 Calibrate the Saybolt Universal viscometer at periodic intervals by measuring the efflux time at 37.8°C (100°F)[100°F] of
an appropriate viscosity oil standard, following the procedure given in Section 10. See Annex A2 for viscosity oil standards
available.
9.2 The efflux time of the viscosity oil standard shall equal the certified Saybolt viscosity value. If the efflux time differs from
the certified value by more than 0.2 %, calculate a correction factor, F, for the viscometer as follows:
F 5 V/t (1)
where:
V = certified Saybolt viscosity of the standard, and
t = measured efflux time at 37.8°C (100°F), s.
t = measured efflux time at 37.8°C [100°F], s.
NOTE 3—If the calibration is based on a viscosity oil standard having an efflux time between 200 and 600 s, the correction factor applies to all viscosity
levels at all temperatures.
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NOTE 1—All dimensions are in millimetres (inches).
FIG. 2 Withdrawal Tube for Use with Saybolt Viscometer
NOTE 1—All dimensions are in millimetres (inches).
FIG. 3 Thermometer Support
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TABLE 1 ASTM Saybolt Viscosity Thermometers
Standard Test ASTM
Thermometer
Temperature Thermometer
Range° C (°F) Subdivisions,° C (°F)
°C (°F) No.
21.1 (70) 17C (17F) 19 to 27 0.1 (0.2)
(66 to 80)
25.0 (77) 17C (17F) 19 to 27 0.1 (0.2)
(66 to 80)
37.8 (100) 18C (18F) 34 to 42 0.1 (0.2)
(94 to 108)
50.0 (122) 19C (19F) 49 to 57 0.1 (0.2)
(120 to 134)
54.4 (130) 19C (19F) 49 to 57 0.1 (0.2)
(120 to 134)
60.0 (140) 20C (20F) 57 to 65 0.1 (0.2)
(134 to 148)
82.2 (180) 21C (21F) 79 to 87 0.1 (0.2)
(174 to 188)
98.9 (210) 22C (22F) 95 to 103 0.1 (0.2)
(204 to 218)
TABLE 1 ASTM Saybolt Viscosity Thermometers
Standard Test ASTM
Thermometer
Temperature Thermometer
Range °C [°F] Subdivisions, °C [°F]
°C [°F] No.
21.1 [70] 17C [17F] 19 to 27 0.1 [0.2]
[66 to 80]
25.0 [77] 17C [17F] 19 to 27 0.1 [0.2]
[66 to 80]
37.8 [100] 18C [18F] 34 to 42 0.1 [0.2]
[94 to 108]
50.0 [122] 19C [19F] 49 to 57 0.1 [0.2]
[120 to 134]
54.4 [130] 19C [19F] 49 to 57 0.1 [0.2]
[120 to 134]
60.0 [140] 20C [20F] 57 to 65 0.1 [0.2]
[134 to 148]
82.2 [180] 21C [21F] 79 to 87 0.1 [0.2]
[174 to 188]
98.9 [210] 22C [22F] 95 to 103 0.1 [0.2]
[204 to 218]
9.3 Calibrate the Saybolt Furol viscometer at 50.0°C (122°F)[122°F] in the same manner as above, using a viscosity oil standard
having a minimum efflux time of 90 s.
9.4 Viscometers or orifices requiring corrections greater than 1.0 % shall not be used in referee testing.
10. Procedure
10.1 Establish and control the bath temperature at the selected test temperature.
10.1.1 Standard test temperatures for measuring Saybolt Universal viscosities are 21.1, 37.8, 54.4, and 98.9°C (70,[70, 100, 130,
and 210°F).210°F].
10.1.2 Standard test temperatures for measuring Saybolt Furol viscosities are 25.0, 37.8, 50.0, and 98.9°C (77,[77, 100, 122,
and 210°F).210°F].
10.1.3 Other standard test temperatures in use include 60.0 and 82.2°C (140[140 and 180°F).180°F].
10.2 Insert a cork stopper, having a cord attached for its easy removal, into the air chamber at the bottom of the viscometer.
The cork shall fit tightly enough to prevent the escape of air, as evidenced by the absence of oil on the cork when it is withdrawn
later as described.
10.3 If the selected test temperature is above room temperature, the test may be expedited by preheating the sample in its
original container to not more than 1.7°C (3.0°F)[3.0°F] above the test temperature. Never preheat any sample to within 28°C
(50°F)[50°F] of its flash point (see Test Methods D93), because volatility losses might alter its composition.
10.4 Stir the sample well; then strain it through the 150-μm (No. 100)[No. 100] wire cloth in the filter funnel directly into the
viscometer until the level is above the overflow rim.
10.5 The viscosities of steam-refined cylinder oils, black lubricating oils, residual fuel oils, and similar waxy products can be
affected by their thermal histories. Use the following preheating procedure with such products to obtain uniform results at
temperatures below 93°C (200°F):[200°F]:
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NOTE 1—All dimensions are in millimetres (inches).
FIG. 4 Filter Funnel for Use with Saybolt Viscometer
10.5.1 Heat the sample in its original container to about 50°C (122°F),[122°F], with stirring and shaking to dissolve and blend
waxy materials. Probe the bottom of the container with a stirring rod to be certain that all waxy materials are in solution, and mix
well.
10.5.2 Pour about 100 mL into a 125-mL Erlenmeyer flask. Stopper loosely with a cork or rubber stopper.
10.5.3 Immerse the flask in a bath of boiling water for 30 min.
10.5.4 Mix well, remove the sample from the boiling water bath, wipe the outside of the flask dry, and strain the sample through
the 75-μm (No. 200)[No. 200] wire cloth in the filter funnel directly into the viscometer until the level is above the overflow rim.
10.6 Stir the sample in the viscometer with the appropriate viscosity thermometer equipped with the thermometer support (Fig.
3). Use a circular motion at 30 to 50 rpm in a horizontal plane. When the sample temperature remains constant within 0.03°C
(0.05°F)[0.05°F] of the test temperature during 1 min of continuous stirring, remove t
...