ASTM C729-75(1995)e1

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
• Technical Committee: C14 - Glass and Glass Products
• Drafting Committee: C14.04 - Physical and Mechanical Properties

Relations

• Replaced By: ASTM C729-75(2000) - Standard Test Method for Density of Glass by the Sink-Float Comparator
• Effective Date: 01-Jan-2000
• 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NOTICE: This standard has either been superseded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
e1
Designation: C 729 – 75 (Reapproved 1995)
AMERICAN SOCIETY FOR TESTING AND MATERIALS
100 Barr Harbor Dr., West Conshohocken, PA 19428
Reprinted from the Annual Book of ASTM Standards. Copyright ASTM
Standard Test Method for
Density of Glass by the Sink-Float Comparator
This standard is issued under the fixed designation C 729; 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 (e) indicates an editorial change since the last revision or reapproval.
e NOTE—Section 11 was added editorially in April 1995.
1. Scope is immersed in a variable-temperature comparator bath. Ini-
tially the solutions, specimen, and standard are at a temperature
1.1 This test method covers the determination of the density
near 25°C, and both the standard and the specimen float in the
of glass or nonporous solids of density from 1.1 to 3.3 g/cm .
solution. The temperature of the system is raised at a uniform
It can be used to determine the apparent density of ceramics or
rate. Because the expansion coefficient of the solution is higher
solids, preferably of known porosity.
than that of the glass standard and specimen, both the standard
1.2 This standard does not purport to address all of the
and the specimen will sink (settle) in the solution. The
safety concerns, if any, associated with its use. It is the
temperatures at which the specimen and standard reach the
responsibility of the user of this standard to establish appro-
mid-point of the test tube are noted and by use of special tables,
priate safety and health practices and determine the applica-
the density of the specimen is obtained.
bility of regulatory limitations prior to use.
3.2 Range of a Given Density Solution—A given density
2. Referenced Documents solution can be used to measure specimens whose density is
within6 0.0200 g/cm of the density of the solution at 35°C, by
2.1 ASTM Standards:
operating the comparator bath in the range 25 to 45°C.
C 693 Test Method for Density of Glass by Buoyancy
D 1217 Test Method for Density and Relative Density
4. Significance and Use
(Specific Gravity) of Liquids by Bingham Pycnometer
4.1 The sink-float comparator method of test for glass
E 12 Terminology Relating to Density and Specific Gravity
density provides the most accurate (yet convenient for practical
of Solids, Liquids, and Gases
applications) method of evaluating the density of small pieces
E 29 Practice for Using Significant Digits in Test Data to
or specimens of glass. The data obtained are useful for daily
Determine Conformance with Specification
quality control of production, acceptance or rejection under
E 77 Test Method for Inspection and Verification of Ther-
specifications, and for special purposes in research and devel-
mometers
opment.
F 77 Test Method for Apparent Density of Ceramics for
4.2 Although this test scope is limited to a density range
Electron Device and Semiconductor Application
from 1.1 to 3.3 g/cm , it may be extended (in principle) to
3. Summary of Method
higher densities by the use of other miscible liquids (Test
Method F 77) such as water and thallium malonate-formate
3.1 The specimen of unknown density is compared with a
(approximately 5.0 g/cm ). The stability of the liquid and the
reference standard of known density. The specimen to be
precision of the test may be reduced somewhat, however, at
measured is placed in a test tube containing a solution whose
higher densities.
density at 35°C is within 0.0200 g/cm of the density of the
specimen at 25°C. The solution is prepared using miscible
5. Apparatus
liquids of known densities bracketing the desired range. The
5.1 Single Tube and Multiple-Tube Comparators (Method
tube also contains a glass density reference standard whose
E 77)—A single-tube comparator can be constructed from
density at 35°C is close to that of the solution at 35°C; the tube
materials readily available in a typical laboratory, and useful if
one wishes to measure the density of materials within a fairly
narrow range, or if only a few tests need to be run each day.
This test method is under the jurisdiction of ASTM Committee C-14 on Glass
and Glass Products and is the direct responsibility of Subcommittee C14.04 on
The multiple-tube comparator can be purchased commer-
Physical and Mechanical Properties.
cially. It is useful if materials with a wide range of density
Current edition approved Aug. 29, 1975. Published November 1975. Originally
must be tested or if many specimens must be tested each day.
published as C 729 – 72 T. Last previous edition C 729 – 72 T.
Annual Book of ASTM Standards, Vol 15.02. The comparators shall consist of the following:
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.
C 729
5.1.1 Single-Tube Comparator (Fig. 1): tube contains density solution and a thermometer; both test
5.1.1.1 Circulating Water Bath, consisting of a 4000-cm tubes employ rubber stoppers for supporting the cage or
beaker, a cover plate supporting test tubes and thermometer, a thermometer.
cooling water coil made from copper tubing, an electrically 5.1.1.3 Thermometers, two, mercury, readable to 0.1°C
driven stirrer, and containing an immersion heater with rheostat between 20 and 50°C. One thermometer passes through a
for controlling heating rate, or heated by an external heat rubber stopper supported by the cover plate into the water bath.
source such as a hot plate. The second thermometer passes through a rubber stopper into
5.1.1.2 Test Tubes, two, 100-cm capacity. The cover plate the test tube that contains density solution only. Thermistor
supports the test tubes, which extended into the water bath. thermometers can be used instead of mercury thermometers, if
One tube contains the density solution, the test specimen, the desired.
standard, and a glass or TFE-fluorocarbon cage (Fig. 2) that 5.1.2 Multiple-Tube Comparator—The commercially ob-
keeps the specimens immersed in the solution. The second test tainable multiple-tube comparator employs the same principle
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
C 729
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
where:
r 5 density of solution − density of standard at
s
35°C,
V 5 volume of solution to be prepared,
s
r and r 5 densities of the component liquids at 35°C,
1 2
and
FIG. 2 TFE-Flourocarbon Cage for 100-mL Test Tube
V and V 5 volumes of the component liquids at 35°C.
1 2
6.2.5 Solution Preparation—Approximate volumes of liq-
as the single-tube comparator, except that the multiple-tube
uids required to supply desired density r are shown in Table 1.
s
type contains additional specimen tubes. These specimen tubes
Mix the two required volumes of liquids 1 and 2 (6.2.4) in a
may contain similar density solutions if a large number of
beaker, set on a hot plate, and warm to 35°C. Place a density
specimens with similar density are to be measured; they may
standard in the solution. Adjust the mixture by adding 1 or
contain density solutions of differing density if a number of
more drops of either component until the density standard
specimens with a range of densities are to be measured.
settles at 35 6 0.2°C in the well-stirred solution.
6. Reagents and Materials
7. Preparation of Density-Temperature Tables
6.1 Density Reference Standards—The reference standard
7.1 Tables are prepared from the equations of this section to
shall be a solid piece of glass with a volume between 0.10 and
relate the specimen density at 25°C to its settling temperature.
0.15 cm , and a ratio of major to minor dimensions not
exceeding 2.0. It shall have a smooth surface and be free of
TABLE 1 Volumes of Liquids for Solutions of Various Densities
seeds, cords, and cracks. A quantity of such standards may be 3
Volume of Material Used, cm
cut from a 20-g piece of glass similarly free of defects, with 3
r g/cm
s
sym-Tetra-
Isopropyl Methylene
density at 25°C (r ) known to 60.0001 g/cm . The density of at 35°C
bromo-
Salicylate Iodide
ethane
such a standard glass can be determined to 60.00001 g/cm by
a precise buoyancy method. Determine the settling tempera-
2.103 135 165 .
2.136 127 173 .
ture of each reference standard to the nearest 0.1°C and discard
2.190 120 180 .
any that deviate more than 0.1°C from mean temperature. Less
2.222 115 185 .
precise density standards are commercially available. 2.236 113 187 .
10 2.257 109 191 .
6.2 Density Solution—The following organic liquids are
2.291 104 196 .
mixed to provide a solution of the desired density:
2.315 100 200 .
6.2.1 Isopropyl Salicylate, density (25°C) approximately 2.335 95 205 .
2.363 92 208 .
1.10 g/cm or alpha-bromonaphthalene, density (25°C) ap-
2.403 85 215 .
proximately 1.49 g/cm .
2.434 80 220 .
2.448 78 222 .
6.2.2 sym-Tetrabromoethane, density (25°C) approximately
2.473 74 226 .
2.96 g/cm .
2.495 70 230 .
6.2.3 Methylene Iodide, density (25°C) approximately 3.32
2.511 68 232 .
g/cm . 2.529 65 235 .
2.560 60 240 .
NOTE 1—Methylene iodide, sym-tetrabromoethane, and alpha- 2.589 56 244 .
2.596 54 246 .
bromonaphthalene are light-sensitive. These liquids should be stored in
2.619 50 250 .
light-protective containers. A piece of copper wire in the methylene iodide
2.633 48 252 .
container will help retard decomposition.
2.669 42 258 .
2.702 37 263 .
6.2.4 The density solution consists of mixtures of iso
...