Page 186 - My FlipBook

154 FILLING MATERIALS

Dry the cavity with alcohol and warm air. Line the
cavity, especially when it is deep, with Caulk Cavity Lining.
Adjust the celluloid matrix.

Place powder and liquid on the slab. Judge the correct
proportions of liquid and powder by estimating their bulk.
The average mix requires, by bulk, about five times more
powder than liquid. These proportions vary a little with
varying temperature.

Place your watch beside the slab.
Begin promptly and complete the mix in a minute and a
quarter. This is important. If more than a minute and a
half is consumed, proper crystalhzation will be interfered with.
At once add half the total powder to the liquid; spatulate

quickly but thoroughly; follow with successive additions of
J
powder in small quantities. Spatulate each addition quickly
and thoroughly until it is perfectly smooth. Keep adding
powder until the mix passes beyond the semi-liquid state and
becomes plastic. In this plastic state it is still soft but does
hot spread smoothly under the spatula; it breaks into soft,

curling ruffles as the spatula moves over it.
With the matrix strip in position, place the Synthetic
Porcelain in the cavity. Work it well into the undercuts and
against the cavity walls. Fill the cavity until there is slight
excess, then bring the celluloid strip over the filling, and hold

it firmly immovable for three and a half minutes by your
watch. Let the Synthetic set normally. Do not burnish.
Do not use either hot or cold air blast.
After three minutes release the strip and immediately
coat the filling with cocoa butter. This prevents evaporation

of the water-of-crystallization.
It is best to defer the final finishing until a subsequent
sitting; but if it is necessary to finish the filling at once, it