Page 62 - My FlipBook

50 MECHANICAL DENTISTRY AND METALLURGY,

mold, SO that when the sections of the flask are brought
together, the rubber, if kept sufficiently hot, will be forced
gradually to the margins of the mold, diminishing, thereby,
the liability of moving or fracturing the gum sections.
After packing the mold the upper section of the flask
should be placed in position, the bolts slipped into place,
and the nuts turned down just enough to hold all in their
proper position.
The flask should now be placed in boiling water for about
one minute, then removed, and the nuts turned down care-
fully and evenly until considerable resistance is offered,

Fig. 25.

when it should be replaced in the boiling water and the
process repeated until the two sections are brought securely
together. The bolts should not now be loosened until the
case has been vulcanized and become cold.
The flask-press, while a very useful instrument when
judiciously employed, should not, as a general thing, be
used by students, for blocks are fractured, teeth forced
out of position, or entire cases are easily and frequently
ruined by undue force being exercised in bringing the sec-
tions together.
If the foregoing directions have been closely followed,
a cross-section of the flask would have the appearance
shown in Fig. 25. The annular grooves shown upon either