ASTM C729-11(2022)

Standard Test Method for Density of Glass by the Sink-Float Comparator

SIGNIFICANCE AND USE
4.1 The sink-float comparator method of test for glass density provides the most accurate (yet convenient for practical applications) method of evaluating the density of small pieces or specimens of glass. The data obtained are useful for daily quality control of production, acceptance or rejection under specifications, and for special purposes in research and development.  
4.2 Although this test scope is limited to a density range from 1.1 g/cm3 to 3.3 g/cm3, it may be extended (in principle) to higher densities by the use of other miscible liquids (Test Method F77) such as water and thallium malonate-formate (approximately 5.0 g/cm3). The stability of the liquid and the precision of the test may be reduced somewhat, however, at higher densities.
SCOPE
1.1 This test method covers the determination of the density of glass or nonporous solids of density from 1.1 g/cm 3 to 3.3 g/cm 3. It can be used to determine the apparent density of ceramics or solids, preferably of known porosity.  
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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
1.3 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.

General Information

• Status: Published
• Publication Date: 31-Jan-2022
• ICS: 81.040.10 - Raw materials and raw glass
• Technical Committee: C14 - Glass and Glass Products
• Drafting Committee: C14.04 - Physical and Mechanical Properties

Relations

• Refers: ASTM D1217-20 - Standard Test Method for Density and Relative Density (Specific Gravity) of Liquids by Bingham Pycnometer
• Effective Date: 01-May-2020
• Refers: ASTM E77-14 - Standard Test Method for Inspection and Verification of Thermometers
• Effective Date: 01-May-2014
• Refers: ASTM D1217-12 - Standard Test Method for Density and Relative Density (Specific Gravity) of Liquids by Bingham Pycnometer
• Effective Date: 01-Nov-2012
• Refers: ASTM D1217-93(2007) - Standard Test Method for Density and Relative Density (Specific Gravity) of Liquids by Bingham Pycnometer
• Effective Date: 01-Dec-2007
• Refers: ASTM E77-07 - Standard Test Method for Inspection and Verification of Thermometers
• Effective Date: 01-Dec-2007
• Refers: ASTM E77-98(2003) - Standard Test Method for Inspection and Verification of Thermometers
• Effective Date: 01-Nov-2003
• Refers: ASTM D1217-93(2003)e1 - Standard Test Method for Density and Relative Density (Specific Gravity) of Liquids by Bingham Pycnometer
• Effective Date: 01-Nov-2003
• Refers: ASTM D1217-93(1998) - Standard Test Method for Density and Relative Density (Specific Gravity) of Liquids by Bingham Pycnometer
• Effective Date: 10-Apr-1998
• Refers: ASTM F77-69(1996) - Test Method for Apparent Density of Ceramics for Electron Device and Semiconductor Application (Withdrawn 2001)
• Effective Date: 01-Jan-1996

Standards Content (Sample)

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.
Designation: C729 − 11 (Reapproved 2022)
Standard Test Method for
Density of Glass by the Sink-Float Comparator
This standard is issued under the fixed designation C729; 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.
1. Scope specimen at 25°C. The solution is prepared using miscible
liquids of known densities bracketing the desired range. The
1.1 Thistestmethodcoversthedeterminationofthedensity
3 tube also contains a glass density reference standard whose
of glass or nonporous solids of density from 1.1g⁄cm to
3 density at 35°C is close to that of the solution at 35°C; the
3.3g⁄cm . It can be used to determine the apparent density of
tube is immersed in a variable-temperature comparator bath.
ceramics or solids, preferably of known porosity.
Initiallythesolutions,specimen,andstandardareatatempera-
1.2 This standard does not purport to address all of the
ture near 25°C, and both the standard and the specimen float
safety concerns, if any, associated with its use. It is the
in the solution. The temperature of the system is raised at a
responsibility of the user of this standard to establish appro-
uniform rate. Because the volumetric expansion coefficient of
priate safety, health, and environmental practices and deter-
the solution is much higher than those of the glass pieces, its
mine the applicability of regulatory limitations prior to use.
density decreases more rapidly and eventually both the stan-
1.3 This international standard was developed in accor-
dard and the specimen will sink (settle) in the solution. The
dance with internationally recognized principles on standard-
temperatures at which the specimen and standard reach the
ization established in the Decision on Principles for the
mid-pointofthetesttubearenotedandbyuseofspecialtables,
Development of International Standards, Guides and Recom-
the density of the specimen is obtained.
mendations issued by the World Trade Organization Technical
3.2 Range of a Given Density Solution—A given density
Barriers to Trade (TBT) Committee.
solution can be used to measure specimens whose density is
within 60.0200 g/cm of the density of the solution at 35°C,
2. Referenced Documents
by operating the comparator bath in the range 25°C to 45°C.
2.1 ASTM Standards:
D1217Test Method for Density and Relative Density (Spe-
4. Significance and Use
cific Gravity) of Liquids by Bingham Pycnometer
4.1 The sink-float comparator method of test for glass
E77Test Method for Inspection and Verification of Ther-
densityprovidesthemostaccurate(yetconvenientforpractical
mometers
applications) method of evaluating the density of small pieces
F77Test Method for Apparent Density of Ceramics for
or specimens of glass. The data obtained are useful for daily
Electron Device and Semiconductor Application (With-
quality control of production, acceptance or rejection under
drawn 2001)
specifications, and for special purposes in research and devel-
opment.
3. Summary of Method
4.2 Although this test scope is limited to a density range
3.1 The specimen of unknown density is compared with a
3 3
from 1.1g⁄cm to 3.3 g/cm , it may be extended (in principle)
reference standard of known density. The specimen to be
to higher densities by the use of other miscible liquids (Test
measured is placed in a test tube containing a solution whose
Method F77) such as water and thallium malonate-formate
density at 35°C is within 0.0200g⁄cm of the density of the
(approximately 5.0 g/cm ). The stability of the liquid and the
precision of the test may be reduced somewhat, however, at
1 higher densities.
This test method is under the jurisdiction of ASTM Committee C14 on Glass
and Glass Products and is the direct responsibility of Subcommittee C14.04 on
5. Apparatus
Physical and Mechanical Properties.
Current edition approved Feb. 1, 2022. Published March 2022. Originally
5.1 Single Tube and Multiple-Tube Comparators (Test
approved in 1972. Last previous edition approved in 2016 as C729–11 (2016).
Method E77)—A single-tube comparator can be constructed
DOI: 10.1520/C0729-11R22.
from materials readily available in a typical laboratory, and
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
useful if one wishes to measure the density of materials within
Standards volume information, refer to the standard’s Document Summary page on
afairlynarrowrange,orifonlyafewtestsneedtoberuneach
the ASTM website.
day. The multiple-tube comparator can be purchased commer-
The last approved version of this historical standard is referenced on
www.astm.org. cially.Itisusefulifmaterialswithawiderangeofdensitymust
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
C729 − 11 (2022)
be tested or if many specimens must be tested each day. The One tube contains the density solution, the test specimen, the
comparators shall consist of the following: standard, and a glass or TFE-fluorocarbon cage (Fig. 2) that
5.1.1 Single-Tube Comparator (Fig. 1): keeps the specimens immersed in the solution.The second test
5.1.1.1 Circulating Water Bath, consisting of a 4000cm tube contains density solution and a thermometer; both test
beaker, a cover plate supporting test tubes and thermometer, a tubes employ rubber stoppers for supporting the cage or
cooling water coil made from copper tubing, an electrically thermometer.
drivenstirrer,andcontaininganimmersionheaterwithrheostat 5.1.1.3 Thermometers, two, mercury, readable to 0.1°C
for controlling heating rate, or heated by an external heat between 20°C and 50°C. One thermometer passes through a
source such as a hot plate. rubberstoppersupportedbythecoverplateintothewaterbath.
5.1.1.2 Test Tubes, two, 100cm capacity. The cover plate The second thermometer passes through a rubber stopper into
supports the test tubes, which extended into the water bath. the test tube that contains density solution only. Thermistors,
Metric Equivalents
1 1 3
in. ⁄4 ⁄2 11 ⁄4 29
mm 6.4 12.7 25.4 44.4 51 229
FIG. 1 Single Tube Sink-Float Density Apparatus
C729 − 11 (2022)
light-protectivecontainers.Apieceofcopperwireinthemethyleneiodide
container will help retard decomposition.
6.2.4 The density solution consists of mixtures of isopropyl
salicylate and sym-tetrabromoethane for densities between
3 3
1.10g⁄cm and 2.96 g/cm , and of sym-tetrabromoethane and
methylene iodide for densities between 2.96 g⁄cm and
3.32g⁄cm . Proper amounts of the two liquids to be used are
found by simultaneous solution of:
ρ V 5ρ V 1ρ V (1)
s s 1 1 2 2
V 5 V 1V (2)
s 1 2
ρ 5 ρ V 1ρ V /~V 1V ! (3)
~ !
s 1 1 2 2 1 2
where:
FIG. 2 TFE-Flourocarbon Cage for 100-mL Test Tube
ρ = density of solution−density of standard at
s
35°C,
V = volume of solution to be prepared,
s
resistive thermal devices (RTD), or thermocouples capable of
ρ and ρ = densities of the component liquids at 35°C,
1 2
measuring and displaying at least 0.1°C accuracy between
and
20°C and 50°C can be used in lieu of mercury thermometers.
V and V = volumes of the component liquids at 35°C.
1 2
5.1.2 Multiple-Tube Comparator—The commercially ob-
6.2.5 Solution Preparation—Approximate volumes of liq-
tainable multiple-tube comparator employs the same principle
uids required to supply desired density ρ are shown in Table
as the single-tube comparator, except that the multiple-tube s
1. Mix the two required volumes of liquids 1 and 2 (6.2.4)in
typecontainsadditionalspecimentubes.Thesespecimentubes
abeaker,setonahotplate,andwarmto35°C.Placeadensity
may contain similar density solutions if a large number of
standard in the solution. Adjust the mixture by adding one or
specimens with similar density are to be measured; they may
contain density solutions of differing density if a number of
specimens with a range of densities are to be measured.
TABLE 1 Volumes of Liquids for Solutions of Various Densities
Volume of Material Used, cm
6. Reagents and Materials
ρ g/cm
s sym-Tetra-
Isopropyl Methylene
at 35°C
bromo-
6.1 Density Reference Standards—The reference standard
Salicylate Iodide
3 ethane
shall be a solid piece of glass with a volume between 0.10cm
2.103 135 165 .
and 0.15 cm , and a ratio of major to minor dimensions not
2.136 127 173 .
exceeding 2.0. It shall have a smooth surface and be free of
2.190 120 180 .
2.222 115 185 .
seeds, cords, and cracks. A quantity of such standards may be
2.236 113 187 .
cut from a 20-g piece of glass similarly free of defects, with
2.257 109 191 .
densityat25°C(ρ )knownto 60.0001g⁄cm .Thedensityof
2.291 104 196 .
2.315 100 200 .
suchastandardglasscanbedeterminedto 60.00001g/cm by
4 2.335 95 205 .
a precise buoyancy method. Determine the settling tempera-
2.363 92 208 .
ture of each reference standard to the nearest 0.1°C and
2.403 85 215 .
2.434 80 220 .
discard any that deviate more than 0.1°C from mean tempera-
2.448 78 222 .
ture. Less precise density standards are commercially avail-
2.473 74 226 .
able.
2.495 70 230 .
2.511 68 232 .
6.2 Density Solution—The following organic liquids are
2.529 65 235 .
mixed to provide a solution of the desired density: 2.560 60 240 .
2.589 56 244 .
6.2.1 Isopropyl Salicylate, density (25°C) approximately
2.596 54 246 .
1.10 g/cm or alpha-bromonaphthalene, density (25°C) ap-
2.619 50 250 .
proximately 1.49 g/cm . 2.633 48 252 .
2.669 42 258 .
6.2.2 sym-Tetrabromoethane, density (25 °C) approxi-
2.702 37 263 .
mately 2.96 g/cm .
2.728 33 267 .
6.2.3 Methylene Iodide, density (25 °C) approximately 2.757 28 272 .
2.812 19 281 .
3.32g⁄cm .
2.847 13 287 .
2.863 10 290 .
NOTE 1—Methylene iodide, sym-tetrabromoethane, and alpha-
2.893 6 294 .
bromonaphthalene are light-sensitive. These liquids should be stored in
2.933 . 300 1
2.960 . 277 23
2.999 . 248 52
Bowman,H.A.,andSchoonover,R.M.,“Proceduref
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