ASTM D4212-10(2014)
(Test Method)Standard Test Method for Viscosity by Dip-Type Viscosity Cups
Standard Test Method for Viscosity by Dip-Type Viscosity Cups
SIGNIFICANCE AND USE
5.1 Viscosity is a measure of the fluidity of a material. Viscosity data are useful in the determination of the ease of stirring, pumping, dip coating, or other flow-related properties of paints and related fluids.
5.2 This type of cup is used to measure viscosity because it is easy to use, robust, and may be used in tanks, reservoirs, and reactors.
5.3 There are other types of apparatus for measuring viscosity in the laboratory that provide better precision and bias, including the Ford viscosity cup (Test Method D1200), and the Brookfield viscometer (Test Methods D2196).
5.4 Certain higher shear rate devices such as cone/plate viscometers (Test Method D4287) provide more information about sprayability, roll coatability, and other high-shear rate related properties of coatings.
SCOPE
1.1 This test method covers the determination of viscosity of paints, varnishes, lacquers, inks, and related liquid materials by dip-type viscosity cups. This test method is recommended for viscosity control work within one plant or laboratory and should be used to check compliance with specifications only when sufficient controls have been instituted to ensure adequate comparability of results.
1.2 Viscosity cups are designed for testing of Newtonian and near-Newtonian liquids. If the test material is non-Newtonian, for example, shear-thinning or thixotropic, another method, such as Test Methods D2196, should be used. Under controlled conditions, comparisons of the viscosity of non-newtonian materials may be helpful, but viscosity determination methods using controlled shear rate or shear stress are preferred.
1.3 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.
1.4 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: D4212 − 10(Reapproved 2014)
Standard Test Method for
Viscosity by Dip-Type Viscosity Cups
This standard is issued under the fixed designation D4212; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope E1 Specification for ASTM Liquid-in-Glass Thermometers
1.1 This test method covers the determination of viscosity
3. Terminology
of paints, varnishes, lacquers, inks, and related liquid materials
3.1 Definitions:
by dip-type viscosity cups. This test method is recommended
3.1.1 near-Newtonian liquid, n—a liquid in which the varia-
for viscosity control work within one plant or laboratory and
tion of viscosity with shear rate is small and the effect on
should be used to check compliance with specifications only
viscosity of mechanical disturbances such as stirring is negli-
when sufficient controls have been instituted to ensure ad-
gible.
equate comparability of results.
3.1.2 Newtonian liquid, n—a liquid in which the viscosity is
1.2 Viscosity cups are designed for testing of Newtonian
independent of the shear stress or shear rate. If the ratio of
and near-Newtonian liquids. If the test material is non-
shear stress to shear rate is not constant, the liquid is non-
Newtonian, for example, shear-thinning or thixotropic, another
Newtonian.
method, such as Test Methods D2196, should be used. Under
controlled conditions, comparisons of the viscosity of non-
4. Summary of Test Method
newtonian materials may be helpful, but viscosity determina-
tion methods using controlled shear rate or shear stress are 4.1 The cup is completely immersed in the material to be
preferred.
tested,withdrawn,andthetimeforthematerialtoflowthrough
a hole in the base of the cup is measured.
1.3 The values stated in SI units are to be regarded as the
standard. The values given in parentheses are for information
5. Significance and Use
only.
5.1 Viscosity is a measure of the fluidity of a material.
1.4 This standard does not purport to address all of the
Viscosity data are useful in the determination of the ease of
safety concerns, if any, associated with its use. It is the
stirring, pumping, dip coating, or other flow-related properties
responsibility of the user of this standard to establish appro-
of paints and related fluids.
priate safety and health practices and determine the applica-
bility of regulatory limitations prior to use.
5.2 This type of cup is used to measure viscosity because it
is easy to use, robust, and may be used in tanks, reservoirs, and
2. Referenced Documents
reactors.
2.1 ASTM Standards:
5.3 There are other types of apparatus for measuring vis-
D1200 Test Method for Viscosity by Ford Viscosity Cup
cosity in the laboratory that provide better precision and bias,
D2196 Test Methods for Rheological Properties of Non-
including the Ford viscosity cup (Test Method D1200), and the
Newtonian Materials by Rotational (Brookfield type)
Brookfield viscometer (Test Methods D2196).
Viscometer
5.4 Certain higher shear rate devices such as cone/plate
D4287 Test Method for High-Shear Viscosity Using a Cone/
viscometers (Test Method D4287) provide more information
Plate Viscometer
about sprayability, roll coatability, and other high-shear rate
related properties of coatings.
This test method is under the jurisdiction of ASTM Committee D01 on Paint
6. Apparatus
and Related Coatings, Materials, andApplications and is the direct responsibility of
Subcommittee D01.24 on Physical Properties of Liquid Paints and Paint Materials.
6.1 Zahn Viscosity Cup—No. 1 through No. 5 Zahn viscos-
Current edition approved Dec. 1, 2014. Published December 2014. Originally
ity cups made of corrosion- and solvent-resistant materials.
approved in 1982. Last previous edition approved in 2010 as D4212 – 10. DOI:
10.1520/D4212-10R14.
The nominal capacity of the cup is 44 mL, but may vary from
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
43 to 49 mL, depending on the manufacturer. A diagram of a
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
ZahncupisgiveninFig.1.Thedimensions,includingorifices,
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. are only approximate because the cups are not made to a
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D4212 − 10 (2014)
NOTE 1—Dimensions are approximate only and may vary with the manufacturer and from batch to batch.
FIG. 1 Zahn Cup Nominal Dimensions
uniform specification. Each manufacturer produces a different 6.2 Shell Viscosity Cup —No. 1 through No. 6 Shell vis-
cup and considerable variation between batches from some cosity cups made of stainless steel with a capacity of 23 mL
manufacturers has been noted in the past. This is a major and a 25-mm (1-in.) long capillary in the bottom and conform-
reason why Zahn cups should not be referenced in specifica- ing to the dimensions shown in Fig. 2.
tions between producer and user only when controls sufficient 6.2.1 Nominal Shell cup orifice diameters are listed in Table
to ensure adequate cup-to-cup and operator-to-operator com- X2.1. Cup Nos. 1 through 2 ⁄2 are recommended for use with
parison are included. (See Appendix X1 for additional infor- reduced rotogravure inks; No. 2 is for use with flexographic
mation on Zahn Cups.) inks; Nos. 3 through 4 are used for industrial enamels,
lacquers, flexographic, and gravure inks; Nos. 5 and 6 are used
NOTE1—Thevariouscupnumbersareforidentificationoftheviscosity
for heavy materials.
ranges within the series only and should not be used for comparison
between different kinds of cups, that is, a No. 2 Zahn cup has no
6.3 Calibration Thermometer—ASTM Saybolt Viscosity
relationship whatsoever with a No. 2 Shell cup.
Thermometer 17F having a range of 66 to 80°F and subdivi-
6.1.1 Nominal Zahn cup orifice diameters are listed in Table
sions of 0.2°F, or 17C having a range of 19 to 27°C and
X2.1. Cup No. 1 with the smallest orifice is used for determin-
ing the viscosity of thin-bodied materials. Cup No. 2 is for use
Shell cups may be obtained from the Norcross Corp., 255 Newtonville Ave.,
Newton, MA02158. This committee is not aware of any other source for flow cups
with clears, lacquers, enamels, and press-side adjustment of
having properties similar enough to the Shell cup to be included in this test method.
flexographic inks; cups Nos. 3 and 4 are for use with more
If you have knowledge of a cup that should be considered, please provide details to
viscous paints and inks (No. 3 for manufacturing of flexog-
ASTM International Headquarters. Your comments will receive careful consider-
raphic inks); and cup No. 5 is used for silk screen inks. ation at a meeting of the responsible technical committee, which you may attend.
D4212 − 10 (2014)
FIG. 2 Shell Cup
subdivisions of 0.1°C, both conforming to the requirements of viscosity determined at one measured temperature may be
Specification E1. Thermometers having subdivisions other converted quickly to a viscosity at another temperature.
than these may be used depending on the sensitivity of the
NOTE 2—When dip cups are used for original purposes, that is thinning
material to be tested, the demands of the application, and the
or monitoring of materials in tanks, coaters, etc., temperature is not
agreement between the purchaser and seller. In addition, important. This is because the key to good operation is to maintain the
fluid within a certain range of dip cup-seconds regardless of the tempera-
temperature measuring devices such as non-mercury liquid-in-
ture of the fluid.
glass thermometers, thermocouples, or platinum resistance
thermometers that provide equivalent or better accuracy and
9. Checking and Calibration of Cups
precision, that cover the temperature range for thermometer
9.1 Cups should be checked in accordance with the proce-
17C and 17F, may be used.
dure described in Appendix X2.The frequency of this depends
6.4 Timer—Any timing device may be used provided that
upon the amount of use and care that the individual cup
the readings can be taken with a discrimination of 0.1 s or
receives, and the level of precision required.
better.
9.2 Cups may be calibrated with standard fluids according
to the procedure in Appendix X3. However, because the
7. Test Materials
viscosity of standard fluids can vary significantly with tem-
7.1 The material to be tested should be visibly homoge-
peratureandduetodifficultyinobtainingadequatetemperature
neous and free from any foreign material or air bubbles.
control with dip cups, calibration is a difficult procedure that
must be done with great care and knowledge.
8. Temperature of Testing
10. Procedure
8.1 Measurements should be made at 25°C (77°F) unless
10.1 Choose the proper cup so that the time of efflux will be
otherwise specified.Temperature drift during the test should be
between 20 and 80 s. See Table 1 for viscosity ranges for the
kept to a minimum. The viscosities of paints and related
various cups.
materials are highly dependent on temperature. Differences in
temperature between measurements can give substantially
NOTE 3—The formulas used in this test method to describe the
different viscosities (up to 5 % per °F). For careful work, the conversionfromZahnsecondstostokesarelinear,theactualcupresponse
is not. The range of 20 to 80 s covers the most linear portion of each cup.
temperature should be taken in the efflux stream, but for
In addition, below 20 s, turbulent flow may cause additional inconsisten-
process control (such as monitoring a dip tank), this is not
cies.Above 80 s, factors that may impact on the precision include; loss of
necessary.
solvent (and therefore varying viscosity), “skinning” of the liquid in the
cup, intermittent flow.
8.2 A temperature correction curve may be constructed for
each liquid by plotting viscosity (seconds) against temperature 10.2 Immerse the cup in the container, which may be a can
over the expected temperature range. With this curve, a or beaker, but is more likely to be a thinning or mixing tank or
D4212 − 10 (2014)
TABLE 1 Approximate Viscosity Ranges, cST (mm /s) (Roughly
cups from the same manufacturer must be used or other action
Corresponding to 20 to 80 s Flow Time)
taken to ensure compatibility of results. The following criteria
Cup Number Zahn Cup Shell Cup
can be used for judging the acceptability of results at the 95 %
A
1 5–60 2–20
confidence level:
2 20–250 10–50
13.1.1 Zahn Cups—Precision was determined on the basis
2 ⁄2 . 20–80
of an interlaboratory test in which six laboratories used new
3 100–800 30–120
3 ⁄2 . 40–170
Zahn cups (all from the same set from the same manufacturer)
4 200–1200 70–270
to test eight paints covering a broad range of viscosities. The
5 400–1800 125–520
within-laboratory coefficient of variation was 3.7 % and the
6 . 320–1300
A
between-laboratories coefficient of variation was 11.5 %.
The lower limit for the Zahn No. 1 cup is 35 s rather than 20 s.
Based on these coefficients the following criteria should be
used for judging the acceptability of results at the 95 %
confidence level:
even a resin reactor. Stir or agitate the fluid well to give
uniform temperature and density. Allow the cup to remain in 13.1.1.1 Repeatability—Two results, each the mean of two
measurements, obtained by the same operator should be
the fluid for 1 to 5 min to attain thermal equilibrium. (Because
of their greater mass, Shell cups should remain in the fluid for considered suspect if they differ by more than 11 % of their
mean value.
the full 5 min.)
13.1.1.2 Reproducibility—Two results, each the mean of
NOTE 4—Dip cups are not recommended for use with thixotropic (time
two measurements, obtained by operators in different labora-
dependent) materials but if used for them (such as gravure or flexographic
tories should be considered suspect if they differ by more than
inks), more vigorous agitation will be necessary to break up the structure
before the measurement is made.
33 % of their mean value.
10.3 Lift the cup vertically out of the material in a quick,
NOTE 6—The values used to determine the precision were obtained
steady motion. As the top edge of the cup breaks the surface,
underidealconditions(asinglesetofcups),reproducibilityinpracticecan
be just as good, by employing strict controls and good techniques.
start the timer. During the time of flow, hold the cup vertically
no more than 15.2 cm (6 in.) above the level of the liquid. Stop
13.1.1.3 Bias—Bias does not apply to this test method as no
the timer at the first definite break in the stream at the base of
acceptable standards exist.
the cup. The efflux time in seconds constitutes the viscosity. It
NOTE 7—Since the precision values were obtained under ideal condi-
is common to make only a single measurement, but for greater
tions (a single set of cups), reproducibility in practice probably is poorer
precision and accuracy the mean of two or more measurements
than that given (perhaps as bad as 50 %).
should be taken.
13.1.2 Shell Cups—Precision was determined on the basis
NOTE 5—The cup should not be held by the loop handle during the
of an interlaboratory test in which four laboratories tested
measurement process. Most manufacturers equip the cup with a ring
seven paints covering a broad range of viscosities. The
through the loop handle. Holding the cup by this ring will help to ensure
within-laboratory coefficient of variation was 3.2 % and the
that the cup hangs vertically.
between-laboratories coefficient of variation was 6.3 %. Based
11. Care of Cups on these coefficients the following criteria should be used for
judging the acceptability of results at the 95 % confidence
11.1 Following each determination, clean the cup with a
level:
suitable solvent and a soft brush. Use no metal tools in contact
13.1.2.1 Repeatability—Two results, each the mean of two
with the instrument as nicks or wear of the drilled orifice affect
measurements, obtained by the same operator should be
the accuracy of the cup.
considered suspect if they differ by more than 9 % of their
12. Report mean value.
13.1.2.2 Reproducibility—Two results, each the mean of
12.1 Report the efflux time to the nearest 0.2 s for Zahn or
two measurements, obtained by operators in different labora-
Shell cup No. ___, manufactured by _____, (in the case of
tories should be considered suspect if they differ
...
This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: D4212 − 10 D4212 − 10 (Reapproved 2014)
Standard Test Method for
Viscosity by Dip-Type Viscosity Cups
This standard is issued under the fixed designation D4212; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope
1.1 This test method covers the determination of viscosity of paints, varnishes, lacquers, inks, and related liquid materials by
dip-type viscosity cups. This test method is recommended for viscosity control work within one plant or laboratory and should be
used to check compliance with specifications only when sufficient controls have been instituted to ensure adequate comparability
of results.
1.2 Viscosity cups are designed for testing of Newtonian and near-Newtonian liquids. If the test material is non-Newtonian, for
example, shear-thinning or thixotropic, another method, such as Test Methods D2196, should be used. Under controlled conditions,
comparisons of the viscosity of non-newtonian materials may be helpful, but viscosity determination methods using controlled
shear rate or shear stress are preferred.
1.3 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.
1.4 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:
D1200 Test Method for Viscosity by Ford Viscosity Cup
D2196 Test Methods for Rheological Properties of Non-Newtonian Materials by Rotational (Brookfield type) Viscometer
D4287 Test Method for High-Shear Viscosity Using a Cone/Plate Viscometer
E1 Specification for ASTM Liquid-in-Glass Thermometers
3. Terminology
3.1 Definitions:
3.1.1 near-Newtonian liquid, n—a liquid in which the variation of viscosity with shear rate is small and the effect on viscosity
of mechanical disturbances such as stirring is negligible.
3.1.2 Newtonian liquid, n—a liquid in which the viscosity is independent of the shear stress or shear rate. If the ratio of shear
stress to shear rate is not constant, the liquid is non-Newtonian.
4. Summary of Test Method
4.1 The cup is completely immersed in the material to be tested, withdrawn, and the time for the material to flow through a hole
in the base of the cup is measured.
5. Significance and Use
5.1 Viscosity is a measure of the fluidity of a material. Viscosity data are useful in the determination of the ease of stirring,
pumping, dip coating, or other flow-related properties of paints and related fluids.
5.2 This type of cup is used to measure viscosity because it is easy to use, robust, and may be used in tanks, reservoirs, and
reactors.
This test method is under the jurisdiction of ASTM Committee D01 on Paint and Related Coatings, Materials, and Applications and is the direct responsibility of
Subcommittee D01.24 on Physical Properties of Liquid Paints and Paint Materials.
Current edition approved July 1, 2010Dec. 1, 2014. Published July 2010December 2014. Originally approved in 1982. Last previous edition approved in 20052010 as
D4212 – 99 (2005).D4212 – 10. DOI: 10.1520/D4212-10.10.1520/D4212-10R14.
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’sstandard’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
D4212 − 10 (2014)
5.3 There are other types of apparatus for measuring viscosity in the laboratory that provide better precision and bias, including
the Ford viscosity cup (Test Method D1200), and the Brookfield viscometer (Test Methods D2196).
5.4 Certain higher shear rate devices such as cone/plate viscometers (Test Method D4287) provide more information about
sprayability, roll coatability, and other high-shear rate related properties of coatings.
6. Apparatus
6.1 Zahn Viscosity Cup—No. 1 through No. 5 Zahn viscosity cups made of corrosion- and solvent-resistant materials. The
nominal capacity of the cup is 44 mL, but may vary from 43 to 49 mL, depending on the manufacturer. A diagram of a Zahn cup
is given in Fig. 1. The dimensions, including orifices, are only approximate because the cups are not made to a uniform
specification. Each manufacturer produces a different cup and considerable variation between batches from some manufacturers
has been noted in the past. This is a major reason why Zahn cups should not be referenced in specifications between producer and
user only when controls sufficient to ensure adequate cup-to-cup and operator-to-operator comparison are included. (See Appendix
X1 for additional information on Zahn Cups.)
NOTE 1—The various cup numbers are for identification of the viscosity ranges within the series only and should not be used for comparison between
different kinds of cups, that is, a No. 2 Zahn cup has no relationship whatsoever with a No. 2 Shell cup.
6.1.1 Nominal Zahn cup orifice diameters are listed in Table X2.1. Cup No. 1 with the smallest orifice is used for determining
the viscosity of thin-bodied materials. Cup No. 2 is for use with clears, lacquers, enamels, and press-side adjustment of
flexographic inks; cups Nos. 3 and 4 are for use with more viscous paints and inks (No. 3 for manufacturing of flexographic inks);
and cup No. 5 is used for silk screen inks.
NOTE 1—Dimensions are approximate only and may vary with the manufacturer and from batch to batchbatch.
FIG. 1 Zahn Cup Nominal Dimensions
D4212 − 10 (2014)
6.2 Shell Viscosity Cup —No. 1 through No. 6 Shell viscosity cups made of stainless steel with a capacity of 23 mL and a
25-mm (1-in.) long capillary in the bottom and conforming to the dimensions shown in Fig. 2.
6.2.1 Nominal Shell cup orifice diameters are listed in Table X2.1. Cup Nos. 1 through 2 ⁄2 are recommended for use with
reduced rotogravure inks; No. 2 is for use with flexographic inks; Nos. 3 through 4 are used for industrial enamels, lacquers,
flexographic, and gravure inks; Nos. 5 and 6 are used for heavy materials.
6.3 Calibration Thermometer—ASTM Saybolt Viscosity Thermometer 17F having a range of 66 to 80°F and subdivisions of
0.2°F, or 17C having a range of 19 to 27°C and subdivisions of 0.1°C, both conforming to the requirements of Specification E1.
Thermometers having subdivisions other than these may be used depending on the sensitivity of the material to be tested, the
demands of the application, and the agreement between the purchaser and seller. In addition, temperature measuring devices such
as non-mercury liquid-in-glass thermometers, thermocouples, or platinum resistance thermometers that provide equivalent or better
accuracy and precision, that cover the temperature range for thermometer 17C and 17F, may be used.
6.4 Timer—Any timing device may be used provided that the readings can be taken with a discrimination of 0.1 s or better.
7. Test Materials
7.1 The material to be tested should be visibly homogeneous and free from any foreign material or air bubbles.
8. Temperature of Testing
8.1 Measurements should be made at 25°C (77°F) unless otherwise specified. Temperature drift during the test should be kept
to a minimum. The viscosities of paints and related materials are highly dependent on temperature. Differences in temperature
between measurements can give substantially different viscosities (up to 5 % per °F). For careful work, the temperature should be
taken in the efflux stream, but for process control (such as monitoring a dip tank), this is not necessary.
8.2 A temperature correction curve may be constructed for each liquid by plotting viscosity (seconds) against temperature over
the expected temperature range. With this curve, a viscosity determined at one measured temperature may be converted quickly
to a viscosity at another temperature.
NOTE 2—When dip cups are used for original purposes, that is thinning or monitoring of materials in tanks, coaters, etc., temperature is not important.
This is because the key to good operation is to maintain the fluid within a certain range of dip cup-seconds regardless of the temperature of the fluid.
Shell cups may be obtained from the Norcross Corp., 255 Newtonville Ave., Newton, MA 02158. This committee is not aware of any other source for flow cups having
properties similar enough to the Shell cup to be included in this test method. If you have knowledge of a cup that should be considered, please provide details to ASTM
International Headquarters. Your comments will receive careful consideration at a meeting of the responsible technical committee, which you may attend.
FIG. 2 Shell Cup
D4212 − 10 (2014)
9. Checking and Calibration of Cups
9.1 Cups should be checked in accordance with the procedure described in Appendix X2. The frequency of this depends upon
the amount of use and care that the individual cup receives, and the level of precision required.
9.2 Cups may be calibrated with standard fluids according to the procedure in Appendix X3. However, because the viscosity
of standard fluids can vary significantly with temperature and due to difficulty in obtaining adequate temperature control with dip
cups, calibration is a difficult procedure that must be done with great care and knowledge.
10. Procedure
10.1 Choose the proper cup so that the time of efflux will be between 20 and 80 s. See Table 1 for viscosity ranges for the various
cups.
NOTE 3—The formulas used in this test method to describe the conversion from Zahn seconds to stokes are linear, the actual cup response is not. The
range of 20 to 80 s covers the most linear portion of each cup. In addition, below 20 s, turbulent flow may cause additional inconsistencies. Above 80
s, factors that may impact on the precision include; loss of solvent (and therefore varying viscosity), “skinning” of the liquid in the cup, intermittent flow.
10.2 Immerse the cup in the container, which may be a can or beaker, but is more likely to be a thinning or mixing tank or even
a resin reactor. Stir or agitate the fluid well to give uniform temperature and density. Allow the cup to remain in the fluid for 1
to 5 min to attain thermal equilibrium. (Because of their greater mass, Shell cups should remain in the fluid for the full 5 min.)
NOTE 4—Dip cups are not recommended for use with thixotropic (time dependent) materials but if used for them (such as gravure or flexographic inks),
more vigorous agitation will be necessary to break up the structure before the measurement is made.
10.3 Lift the cup vertically out of the material in a quick, steady motion. As the top edge of the cup breaks the surface, start
the timer. During the time of flow, hold the cup vertically no more than 15.2 cm (6 in.) above the level of the liquid. Stop the timer
at the first definite break in the stream at the base of the cup. The efflux time in seconds constitutes the viscosity. It is common
to make only a single measurement, but for greater precision and accuracy the mean of two or more measurements should be taken.
NOTE 5—The cup should not be held by the loop handle during the measurement process. Most manufacturers equip the cup with a ring through the
loop handle. Holding the cup by this ring will help to ensure that the cup hangs vertically.
11. Care of Cups
11.1 Following each determination, clean the cup with a suitable solvent and a soft brush. Use no metal tools in contact with
the instrument as nicks or wear of the drilled orifice affect the accuracy of the cup.
12. Report
12.1 Report the efflux time to the nearest 0.2 s for Zahn or Shell cup No. ___, manufactured by _____, (in the case of Zahn
cups) the temperature of the fluid (where measured), and whether the result is from a single measurement or the mean of two of
more measurements.
13. Precision and Bias
13.1 The most satisfactory results when using dip cups are obtained when viscosity is being controlled at a single location only.
However, when comparisons between locations are made, cups from the same manufacturer must be used or other action taken
to ensure compatibility of results. The following criteria can be used for judging the acceptability of results at the 95 % confidence
level:
13.1.1 Zahn Cups—Precision was determined on the basis of an interlaboratory test in which six laboratories used new Zahn
cups (all from the same set from the same manufacturer) to test eight paints covering a broad range of viscosities. The
within-laboratory coefficient of variation was 3.7 % and the between-laboratories coefficient of variation was 11.5 %. Based on
these coefficients the following criteria should be used for judging the acceptability of results at the 95 % confidence level:
TABLE 1 Approximate Viscosity Ranges, cST (mm /s) (Roughly
Corresponding to 20 to 80 s Flow Time)
Cup Number Zahn Cup Shell Cup
A
1 5–60 2–20
2 20–250 10–50
2 ⁄2 . 20–80
3 100–800 30–120
3 ⁄2 . 40–170
4 200–1200 70–270
5 400–1800 125–520
6 . 320–1300
A
The lower limit for the Zahn No. 1 cup is 35 s rather than 20 s.
D4212 − 10 (2014)
13.1.1.1 Repeatability—Two results, each the mean of two measurements, obtained by the same operator should be considered
suspect if they differ by more than 11 % of their mean value.
13.1.1.2 Reproducibility—Two results, each the mean of two measurements, obtained by operators in different laboratories
should be considered suspect if they differ by more than 33 % of their mean value.
NOTE 6—The values used to determine the precision were obtained under ideal conditions (a single set of cups), reproducibility in practice can be just
as good, by employing strict controls and good techniques.
13.1.1.3 Bias—Bias does not apply to this test method as no acceptable standards exist.
NOTE 7—Since the precision values were obtained under ideal conditions (a single set of cups), reproducibility in practice probably is poorer than th
...
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