IMPROVEMENTS IN THE MANUFACTURE OF MODELS AND OF PLATES' OR 'PIECES' FOR ARTIFICIAL TEETH
Year: 1862

page_text: PROVISIONAL SPECIFICATION left by Matthew Cartwright at the Office
of the Commissioners of Patents, with bis Petition, on the 2nd January
1862.
I, MATTHEW CARTWRIGHT, of Carlisle, in the County of Cumberland, Dentist,
do hereby declare the nature of the said Invention for "IMPROVEMENTS IN THE
MANUFACTURE OF MODELS AND OF PLATES' OR 'PIECES' FOR ARTIFICIAL TEETH,"
to be as follows:-
My Invention consists in making models used in preparing plates or pieces
for artificial teeth of vulcanite, ebonite, or hardened rubber, alone or combined
with soft vulcanized rubber in the manner hereafter described.
I take a cast or impression of the mouth in wax, coat the surface of it with
plaster of Paris, and when dry, paint it with a mixture composed of oil and
vermilion. The cast or impression then receives a second coat of plaster,
which, when dry, again receives a coat of oil and vermilion, and so on until it
is sufficiently thick for the purpose to which it is to be applied. The wax is
removed, and the whole is coated with vermilion and oil as before. The
model just made is inserted in the lower half of a flask containing liquid
plaster, from which, when hardened, the model is removed, and its counterpart
or impression is reproduced in the plaster. The space formed by the model

page_text: in the plaster is now filled with wax, and the rest of the plaster coated with
vermilion and oil; the upper half or portion of the flask is now placed on the
lower half and filled with liquid plaster, a cover is placed on it, and the whole
allowed to harden. The upper and lower flasks are now divided, the wax in
the lower flask is picked out, and the space thereby formed is filled up with
the composition of india-rubber to form vulcanite, the flasks are again put
together, heated, and subjected to pressure in the ordinary manner, and the
rubber is finally vulcanized. This done, the flasks are opened, and the model
removed. To produce a counter model in vulcanite, I coat the vulcanite
model with black lead, lamp black, bronze, goldbeaters' skin, or other suitable
material, and place it in the lower half of the flask (that part representing the
mouth being uppermost), which contains soft plaster, where it is allowed to
harden. The whole, or as much of the model as necessary, is now covered
with wax, and the lower half painted in the ordinary manner; the upper half
of the flask, which is filled with plaster, is now put on the lid, is also placed
on, and the whole allowed to harden. This accomplished, the flasks are
separated, the wax removed, and india-rubber composition inserted in the
cavity it occupied; the flasks are again put together, heated, pressed, and
the india-rubber vulcanized in the ordinary manner. Sometimes I form
the models and their counterparts by painting the india-rubber when in a
liquid state on the model, each coat being dry before the next is applied.
When an elastic model is required, soft and hard rubber are used alternately
or hard rubber in combination with cotton or any other material capable of
rendering it elastic. For rendering plates or pieces suitable for palates, gums,
or bands elastic, I coat the base with, for example, two coats of hard rubber;
then I apply a series of coats of soft rubber, and so on, according to the degree
of thickness and elasticity required; and this may be done in combination.or
not with any other material capable of rendering it elastic, such as cotton,
cotton fabric, asbestos. Where strength is required, hard rubber must exceed
the soft, and where elasticity is required, the soft rubber must exceed the
hard. Plates or pieces made in the manner before described may be coated
with crystal or plastic gold, gold leaf, platina leaf, tin foil, gold shell, silica,
filings of gold or other metal in the following manner:-I adapt crystal or
plastic gold to the models by consolidating it on them, the surface of the gold
being roughened; the gold then receives a coating of liquid composition to
form vulcanite; the model is then placed in a "digester" or oven to heat it;
when removed, it is again coated with a composition, as before, and so on,
until the desired thickness is obtained; when perfectly solid, another layer, or

page_text: even two or more layers of hard india-rubber, is or are added, and crystal
gold adapted to it; the whole is vulcanized. I adapt gold leaf, tin or platina
foil to the models by means of a sponge or other soft material. (When thick
fuil is used, it must be rendered porous.) The foil then receives a coating of
hard india-rubber, and is heated. The upper part of the piece is coated with
gold filings, precipitated gold, or gold shell, by scattering the filings upon the
surface previous to its being dry, and applying the gold shell when the surface
is partially dry. To cover that part fitting the mouth with gold shell, I paint
the model with it by means of a camel hair brush. In all cases I prefer the
metal leaf to be roughened. To apply silica to the plates, I take an impalpable
powder of it, and paint it on by dipping the brush in a solution of sugar and
water; the silica may be colored when desired.