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48 MECHANICAL DENTISTRY AND METALLURGY.
Ijoiling water, with the liask placed as such an angle that
any particles of wax will be readily carried off.
Outlet Grooves or Gates.—The next step is to make
grooves or " gates " which will act as receptacles for the
excess of rubber. Tliis is clone by cutting a groove around
the cast, part way l.)etween it and the margin of the flask,
as shown in h^ig. 24. The groove should l)e beveled from

Fig. 24.

its bottom toward the casts to within about one-sixteenth
of an inch of the border. The top of this septum is then
slightly scraped. This must be carefully done, as it is
desirable to simply trim ofT the sharp edges and a thin and
uniform layer of the plaster from its entire surface, which
will more readily allow the passage of the surplus rubber
into the annular groove. This method was first suggested
by Dr. \V. Storer How, in The Dental Cosmos.
The old method, and that practiced to-day by many, is
to cut radiating grooves about one-fourth of an inch apart,
leading from the cast to the larger or annular groove. As
Dr. How says of this, the radial gates really defeat the true