54 
BULLKTTX 1210, V. S. DEPARTMENT OF AC! IU CULTURE. 
penetrates a sample of the material under known conditions of 
loading, time, and temperature. Where the conditions of test are 
imt specifically mentioned, the load, time, and temperature are 
understood to be loo grams, 5 seconds, 20° C. (77° F.), respec- 
tively, and the units of penetration to indicate hundredths of a 
centimeter. 
II. APPARATUS. 
Container. 
Needle. 
2. The container for holding the material to be tested shall be 
a flat-bottom, cylindrical dish, ,")."» millimeters [2& inches) in 
diameter and 35 millimeters (11 Inches) deep. 14 
3. The needle for this test shall be a cylindrical steel rod 50.8 
millimeters (2 inches) long, having a diameter of 1.01 to l.<>2 mil- 
limeters and having a taper of 6.34 to 6.86 millimeters measured 
on the axis. After tapering, the point shall he "blunted" by 
grinding off to a truncated cone, the smaller base of which shall 
be from 0.14 to 0.1*> millimeters in diameter. A Roberts No. 2 
parabola needle checked against the standard needle may be used. 
4. The water bath shall be maintained at a temperature not 
varying more than 0.1° C. from 25° C. (77° F.). The volume of 
<\ ater shall be not less than 10 liters and the sample shall be 
immersed to a depth of not less than 10 centimeters (4 inches) 
atid shall he supported on a perforated shelf not less than 5 centi- 
meters (2 inches) from the bottom of the bath. 
5. Any apparatus which will allow the needle to penetrate with- 
out appreciable friction, and which is accurately calibrated to 
yield results in accordance with the definition of penetration, will 
be acceptable. 
6. The transfer dish for the container shall be a small dish or 
tray of such capacity as will insure complete immersion of the 
container during the test. It shall he provided with some means 
which will insure a firm hearing and prevent rocking of the con- 
tainer. 
III. PREPARATION OF SAMPLE. 
7. The sample shall be completely melted at the lowest possi- 
ble temperature and stirred thoroughly until it is homogenous 
and i'vvc from air bubbles. It shall then he poured into the sam- 
ple container to a depth of less than 15 millimeters (five-eight lis 
inches). The sample shall he protected from dust and allowed to 
cool in an atmosphere not lower than 18° C. (65° F.) for one 
hour. It shall then be placed in the water bath along with the 
transfer dish and allowed to remain one hour. 
IV. PROCEDURE. 
Method of test. 8. (a) In making the test the sample shall he placed in the 
transfer dish filled with water from the water bath of sufficient 
depth completely to cover the container. The transfer dish 
containing the sample shall be placed upon the stand of the pene- 
tration machine. The needle loaded with Specified weight, shall 
he adjusted t<, make contact with the surface of the sample. This 
may he accomplished by making contact of the actual needle poinl 
with Its image reflected by the surface of the sample from a 
properly placed source of light. Either the reading of the dial 
shall then he noted or the needle brought to zero. The needle 
is then released for the specified period of time, after which the 
penetration machine is adjusted to measure the distance pene- 
trated. 
At leasl three tests shall be made at points on the surface of 
the sample qoI less than 1 centimeter (three-eighths inch) from 
the side of the container and not less than l centimeter (three- 
u This requirement Is fulfilled by tin- American Can Co.'s gll] stylo 
ointment box, deep pattern, .''.ounce capacity. 
Water bath. 
Penetration 
machine. 
Transfer 
dish. 
Preparation 
of sample. 
