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Designation: D 61 – 75 (Reapproved 1999)

An American National Standard

Standard Test Method for

Softening Point of Pitches (Cube-in-Water Method)1
This standard is issued under the fixed designation D 61; 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 theyear of last reapproval. A superscript
epsilon (e) indicates an editorial change since the last revision or reapproval.

5. Apparatus
5.1 Mold—A mold suitable for forming two 1⁄2in. (12.7mm) cubes of pitch, having cylindrical core pins 12 gage (2.05
mm) in diameter located in the base plate of the assembly to
produce accurately centered suspension holes in the cubes.
(See Fig. 1.)
5.2Hooks—Two L-shaped hooks, made of 12-gage (2.05mm) copper wire. The foot of the hook shall be 1 in. (25- mm)
long and at a right angle to the upright portion for insertion into
the center hole of the pitch cube.
5.3 Container—A glass vessel that can be heated, not less
than 85 mm in diameter and 105 mm deep. (A standard 600-mL
low-form beaker meets these requirements).
5.4 Thermometer—An ASTM LowSoftening Point Thermometer having a range from 30 to 180°F (−2 to 80°C) and
conforming to the requirements for Thermometer 15F (15C) as
described in Specification E 1.
5.5 Heat Source:
5.5.1 Electric Heater—A hot plate or immersion heater
provided with a variable transformer or other device suitable
for regulating the temperature of the heating element.
5.5.2 Gas Heater—A bunsen-type burner,fitted with a
chimney.

1. Scope
1.1 This test method covers the determination of the softening point of pitches below 176°F (80°C) by this method.
Pitches of higher softening point should be tested by Test
Method D 2319 or Test Method D 3104.
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 ofthis 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:
D 140 Practice for Sampling Bituminous Materials2
D 2319 Test Method for Softening Point of Pitch (Cube-inAir Method)3
D 3104 Test Method for Softening Point of Pitches (Mettler
Softening Point Method)4
E 1Specification for ASTM Thermometers5
3. Summary of Test Method
3.1 Two cubes of pitch, supported on wire hooks, are heated
at a controlled rate in water in a glass container. The softening
point is defined as the mean of the temperatures at which the
cubes sag downwards a distance of 25 mm.

6. Sampling
6.1 Samples from shipments shall be taken in accordance
with Practice D 140 and shall befree of foreign substances.
Thoroughly mix the sample before removing a representative
portion for the determination or for dehydration.
6.2 If the presence of water is indicated by surface foam on
heating, maintain the sample at a temperature of about 260°F
(125°C) in an open container until the surface is free of foam.
Take care not to overheat, and remove from the heat source as
soon asthe foam has subsided.

4. Significance and Use
4.1 Pitch does not go through a solid-liquid phase change
when heated, and therefore does not have a true melting point.
As the temperature rises, pitch softens and becomes less
viscous. The softening point is arbitrarily defined and must be
established by a closely controlled method which must be
carefully followed if test results are to bereproducible.
4.2 This test is useful in determining the consistency of
pitch as one element in establishing the uniformity of shipments or sources of supply.

7. Test Specimens
7.1 Coat the inner surfaces and core pins of the mold very
lightly with silicone oil or silicone grease. Form the pitch into
truly shaped cubes either by pressing (7.2) or by pouring (7.4),
the latter being...