ASTM C693-93(1998)

NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
Designation: C 693 – 93 (Reapproved 1998)
Standard Test Method for
Density of Glass by Buoyancy
This standard is issued under the fixed designation C 693; 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.
1. Scope 5.4 Nickel-Chromium-Iron or Platinum-Alloy Wire, less
than 0.2-mm diameter for suspending the specimen either in a
1.1 This test method covers the determination of the density
basket or a loop made of the same wire. The suspension wire
of glasses at or near 25°C, by buoyancy.
shall be cleaned by degreasing or heating in a vacuum. An
1.2 This standard does not purport to address all of the
acceptable alternative method of cleaning the platinum-alloy
safety concerns, if any, associated with its use. It is the
wire is to heat in an oxidizing gas flame until there is no longer
responsibility of the user of this standard to establish apppro-
any color emitted from the gases passing around the wire.
priate safety and health practices and determine the applica-
5.5 Weights, with accuracy of 0.1 mg.
bility of regulatory limitations prior to use.
5.6 Barometer, with sensitivity of 1-mm Hg (optional, see
2. Referenced Documents Note 3).
2.1 ASTM Standards:
6. Reagent
E 12 Terminology Relating to Density and Specific Gravity
2 6.1 Distilled Water, fresh, boiled, and used within 24 h,
of Solids, Liquids, and Gases
allowed to stabilize at balance air temperature for at least 2 h
3. Terminology in the beaker.
3.1 Definition:
7. Test Specimen
3.1.1 density of solids—the mass of a unit volume of a
7.1 Specimens weighing about 20 g, with a minimum of
material at a specified temperature. The units shall be stated as
seeds or other inclusions (Note 1), shall be taken or cut from
grams per cubic centimetre (see Terminology E 12).
the sample object, preferably in cylindrical or rectangular bar
4. Significance and Use
form with smooth, slightly rounded surfaces having no cracks
or sharp edges.
4.1 Density as a fundamental property of glass has basic
significance. It is useful in the physical description of the glass
NOTE 1—For a specimen of 20 g with a density of approximately 2.5
and as essential data for research, development, engineering,
g/cm , a gaseous void of diameter 2 mm will cause an error in measured
and production. density of 0.05 %.
7.2 The specimens shall be cleaned, handling them with
5. Apparatus
tweezers throughout subsequent operations, by immersion
5.1 Analytical Balance, with sensitivity and accuracy of 0.1
preferably in an ultrasonic bath of hot nitric acid, chromic-
mg.
sulfuric acid, or organic degreasing solvent, followed by a
5.2 Beaker, of convenient capacity (250 to 750 cm )tofit
rinsing in alcohol and distilled water. For samples only soiled
inside the balance chamber and allow immersion of the basket
by ordinary handling or exposure, adequate cleaning may be
or wire loop specimen holder in distilled water. 4
obtained using a warm 2 % volume MICRO-brand detergent,
5.3 Thermometers, calibrated (20 to 30°C), sensitive to
followed by a deionized or distilled water rinse.
0.1°C for determining air and water temperatures.
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
Physical and Mechanical Properties. Bowman, H. A., and Schoonover, R. M., “Procedure for High Precision Density
Current edition approved May 15, 1993. Published July 1993. Originally Determinations by Hydrostatic Weighing.” Journal of Research, National Bureau of
e1
published as C 693 – 71 T. Last previous edition C 693 – 84 (1988) . Standards, Vol 71C, No. 3, July–August 1967, pp. 179–198.
2 4
Discontinued—Replaced by E 1547, Annual Book of ASTM Standards,Vol Manufactured by International Products Corporation, PO Box 70, Burlington,
15.05. NJ 08016.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
C 693 – 93 (1998)
8. Procedure 9. Calculation
9.1 Calculate the weight of the specimen in water, W ,as
8.1 Hold the specimens and covered beaker of boiled W
follows:
distilled water near the laboratory balance until the water has
cooled to ambient temperature before weighing.
W 5 W 2 W (1)
W T O
8.2 Read the laboratory air temperature to the nearest 1°C.
9.2 Calculate the glass density, r, at the average air-water
Read the barometric pressure to the nearest 1-mm Hg. A fixed
laboratory temperature, T , as follows:
L
laboratory average barometric pressure estimate is an accept-
~W r 2 W r !
A W W A
able alternative to the barometric pressure measurement (see
r5 (2)
~W 2 W !
A W
Note 3). Determine the density, r , of the air from Table 1.
A
9.3 Calculate the glass density, r , at a standard reference
S
8.3 Weigh the glass specimen in air to the nearest 0.1 mg
temperature, T , as follows:
S
and record as W .
A
r
8.4 Place the beaker of water with immersed thermometer
r 5 (3)
S
1 1 3a~T 2 T !
S L
on a platform supporting it over the balance pan so that the pan
where a is the approximate instantaneous coefficient of
...