ASTM C729-75(2000)

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

SCOPE
1.1 This test method covers the determination of the density of glass or nonporous solids of density from 1.1 to 3.3 g/cm. 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 and health practices and determine the applicability of regulatory limitations prior to use.

General Information

• Status: Historical
• Publication Date: 31-Dec-1999
• 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

• Replaces: ASTM C729-75(1995)e1 - Standard Test Method for Density of Glass by the Sink-Float Comparator
• Effective Date: 01-Jan-2000
• Replaced By: ASTM C729-05 - Standard Test Method for Density of Glass by the Sink-Float Comparator
• Effective Date: 15-Sep-2005
• Referred By: ASTM F1538-03(2017) - Standard Specification for Glass and Glass Ceramic Biomaterials for Implantation
• Effective Date: 01-Jan-2000
• Referred By: ASTM E438-92(2018) - Standard Specification for Glasses in Laboratory Apparatus
• Effective Date: 01-Jan-2000

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NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.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:C729–75(Reapproved 2000)
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 (e) indicates an editorial change since the last revision or reapproval.
1. Scope tiallythesolutions,specimen,andstandardareatatemperature
near 25°C, and both the standard and the specimen float in the
1.1 Thistestmethodcoversthedeterminationofthedensity
solution. The temperature of the system is raised at a uniform
of glass or nonporous solids of density from 1.1 to 3.3 g/cm .
rate.Becausetheexpansioncoefficientofthesolutionishigher
It can be used to determine the apparent density of ceramics or
than that of the glass standard and specimen, both the standard
solids, preferably of known porosity.
and the specimen will sink (settle) in the solution. The
1.2 This standard does not purport to address all of the
temperatures at which the specimen and standard reach the
safety concerns, if any, associated with its use. It is the
mid-pointofthetesttubearenotedandbyuseofspecialtables,
responsibility of the user of this standard to establish appro-
the density of the specimen is obtained.
priate safety and health practices and determine the applica-
3.2 Range of a Given Density Solution— A given density
bility of regulatory limitations prior to use.
solution can be used to measure specimens whose density is
2. Referenced Documents within60.0200g/cm ofthedensityofthesolutionat35°C,by
operating the comparator bath in the range 25 to 45°C.
2.1 ASTM Standards:
C693 Test Method for Density of Glass by Buoyancy
4. Significance and Use
D1217 Test Method for Density and Relative Density
4.1 The sink-float comparator method of test for glass
(Specific Gravity) of Liquids by Bingham Pycnometer
densityprovidesthemostaccurate(yetconvenientforpractical
E12 Terminology Relating to Density and Specific Gravity
applications) method of evaluating the density of small pieces
of Solids, Liquids, and Gases
or specimens of glass. The data obtained are useful for daily
E29 Practice for Using Significant Digits in Test Data to
quality control of production, acceptance or rejection under
Determine Conformance with Specification
specifications, and for special purposes in research and devel-
E77 Test Method for Inspection and Verification of Ther-
opment.
mometers
4.2 Although this test scope is limited to a density range
F77 Test Method for Apparent Density of Ceramics for
2 from 1.1 to 3.3 g/cm , it may be extended (in principle) to
Electron Device and Semiconductor Application
higher densities by the use of other miscible liquids (Test
3. Summary of Method Method F77) such as water and thallium malonate-formate
(approximately 5.0 g/cm ). The stability of the liquid and the
3.1 The specimen of unknown density is compared with a
precision of the test may be reduced somewhat, however, at
reference standard of known density. The specimen to be
higher densities.
measured is placed in a test tube containing a solution whose
density at 35°C is within 0.0200 g/cm of the density of the
5. Apparatus
specimen at 25°C. The solution is prepared using miscible
5.1 Single Tube and Multiple-Tube Comparators (Method
liquids of known densities bracketing the desired range. The
E77)— A single-tube comparator can be constructed from
tube also contains a glass density reference standard whose
materials readily available in a typical laboratory, and useful if
densityat35°Cisclosetothatofthesolutionat35°C;thetube
one wishes to measure the density of materials within a fairly
is immersed in a variable-temperature comparator bath. Ini-
narrow range, or if only a few tests need to be run each day.
The multiple-tube comparator can be purchased commer-
1 7
This test method is under the jurisdiction ofASTM Committee C-14 on Glass
cially. It is useful if materials with a wide range of density
and Glass Products and is the direct responsibility of Subcommittee C14.04 on
must be tested or if many specimens must be tested each day.
Physical and Mechanical Properties.
The comparators shall consist of the following:
Current edition approved Aug. 29, 1975. Published November 1975. Originally
5.1.1 Single-Tube Comparator (Fig. 1):
published as C729–72T. Last previous edition C729–72T.
Annual Book of ASTM Standards, Vol 15.02.
Annual Book of ASTM Standards, Vol 05.01.
Annual Book of ASTM Standards, Vol 15.05.
5 7
Annual Book of ASTM Standards, Vol 14.02. A multiple-tube comparator is available from American Glass Research, Inc.,
Annual Book of ASTM Standards, Vol 14.03. Box 149, Butler, PA 16001.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
C729–75 (2000)
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
5.1.1.1 Circulating Water Bath, consisting of a 4000-cm keeps the specimens immersed in the solution.The second test
beaker, a cover plate supporting test tubes and thermometer, a tube contains density solution and a thermometer; both test
cooling water coil made from copper tubing, an electrically
tubes employ rubber stoppers for supporting the cage or
drivenstirrer,andcontaininganimmersionheaterwithrheostat
thermometer.
for controlling heating rate, or heated by an external heat
5.1.1.3 Thermometers, two, mercury, readable to 0.1°C
source such as a hot plate.
between 20 and 50°C. One thermometer passes through a
5.1.1.2 Test Tubes, two, 100-cm capacity. The cover plate
rubberstoppersupportedbythecoverplateintothewaterbath.
supports the test tubes, which extended into the water bath.
The second thermometer passes through a rubber stopper into
One tube contains the density solution, the test specimen, the
standard, and a glass or TFE-fluorocarbon cage (Fig. 2) that
C729–75 (2000)
NOTE 1—Methylene iodide, sym-tetrabromoethane, and alpha-
bromonaphthalene are light-sensitive. These liquids should be stored in
light-protectivecontainers.Apieceofcopperwireinthemethyleneiodide
container will help retard decomposition.
6.2.4 The density solution consists of mixtures of isopropyl
salicylateand sym-tetrabromoethanefordensitiesbetween1.10
and 2.96 g/cm , and of sym-tetrabromoethane and methylene
iodide for densities between 2.96 and 3.32 g/cm . Proper
amounts of the two liquids to be used are found by simulta-
neous solution of:
r V 5r V 1r V (1)
s s 1 1 2 2
V 5 V 1 V (2)
s 1 2
r 5 ~r V 1r V !/~V 1 V ! (3)
s 1 1 2 2 1 2
FIG. 2 TFE-Flourocarbon Cage for 100-mL Test Tube
where:
r = density of solution−density of standard at
s
the test tube that contains density solution only. Thermistor
35°C,
thermometers can be used instead of mercury thermometers, if
V = volume of solution to be prepared,
s
desired. r and r = densities of the component liquids at 35°C,
1 2
5.1.2 Multiple-Tube Comparator—The commercially ob- and
V and V = volumes of the component liquids at 35°C.
tainable multiple-tube comparator employs the same principle
1 2
as the single-tube comparator, except that the multiple-tube 6.2.5 Solution Preparation—Approximate volumes of liq-
uids required to supply desired density r are shown in Table
typecontainsadditionalspecimentubes.Thesespecimentubes
s
may contain similar density solutions if a large number of 1. Mix the two required volumes of liquids 1 and 2 (6.2.4) in
a beaker, set on a hot plate, and warm to 35°C. Place a density
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
r g/cm
s
sym-Tetra-
Isopropyl Methylene
at 35°C
bromo-
6.1 Density Reference Standards—The reference standard
Salicylate Iodide
ethane
shall be a solid piece of glass with a volume between 0.10 and
2.103 135 165 .
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 .
seeds, cords, and cracks.Aquantity of such standards may be 2.222 115 185 .
2.236 113 187 .
cut from a 20-g piece of glass similarly free of defects, with
3 2.257 109 191 .
density at 25°C (r ) known to 60.0001 g/cm .The density of
2.291 104 196 .
suchastandardglasscanbedeterminedto 60.00001g/cm by
2.315 100 200 .
2.335 95 205 .
a precise buoyancy method. Determine the settling tempera-
2.363 92 208 .
tureofeachreferencestandardtothenearest0.1°Canddiscard
2.403 85 215 .
anythatdeviatemorethan0.1°Cfrommeantemperature.Less
2.434 80 220 .
2.448 78 222 .
precise density standards are commercially available.
2.473 74 226 .
6.2 Density Solution—The following organic liquids are
2.495 70 230 .
mixed to provide a solution of the desired density: 2.511 68 232 .
2.529 65 235 .
6.2.1 Isopropyl Salicylate, density (25°C) approximately
2.560 60 240 .
1.10 g/cm or alpha-bromonaphthalene, density (25°C) ap-
2.589 56 244 .
proximately 1.49 g/cm . 2.596 54 246 .
2.619 50 250 .
6.2.2 sym-Tetrabromoethane, density (25°C) approximately
2.633 48 252 .
2.96 g/cm .
2.669 42 258 .
6.2.3 Methylene Iodide, density (25°C) approximately 3.32 2.702 37 263 .
2.728 33 267 .
g/cm .
2.757 28 272 .
2.812 19 281 .
2.847 13 287 .
2.863 10 290 .
Bowman,H.A.,andSchoonover,R.M.,“ProcedureforHighPrecisionDensity
2.893 6 294 .
DeterminationsbyHydrostaticWeighing,” Journal of Research,NationalBureauof
2.933 . 300 1
Standards, 71C, 3, 1967, p. 179.
2.960 . 277 23
Sources include:
2.999 . 248 52
American Glass Research, Inc., Box 149, Butler, PA 16001,
3.035 . 214 86
EmhartCorporation,HartfordDivision,P.O.Box1620,Hartford,CT06102,and
3.054 . 198 102
Engineered Materials, P.O. Box 363, Church St.
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