6.2 Time of Setting Determination— Allow the time of
setting specimen to remain in the moist cabinet for 30 min after
molding without being disturbed. Determine the penetration of
the 1-mm needle at this time and every 15 min thereafter (every
10 min for Type III cements) until a penetration of 25 mm or
less is obtained. For the penetration test, lower the needle D ofthe rod B until it rests on the surface of the cement paste.
Tighten the set screw, E, and set the indicator, F, at the upper
end of the scale, or take an initial reading. Release the rod
quickly by releasing the set screw, E, and allow the needle to
settle for 30 s; then take the reading to determine the
penetration. (If the paste is obviously quite soft on the early
readings, the fall of the rod may be retarded to avoid bending
the 1-mm needle, but the rod shall be released only by the set
screw when actual determinations for the setting time are
made.) No penetration test shall be made closer than 1⁄4 in. (6.4
mm) from any previous penetration and no penetration test
shall be made closer than 3⁄8 in. (9.5 mm) from the inside of the
mold. Record the results of all penetration tests and, by
interpolation, determine the time when a penetration of 25 mm
is obtained. This is the initial setting time. The final setting
time is when the needle does not sink visibly into the paste.