IMPROVEMENTS IN THE MANUFACTURE OF CERAMIC TESSERE AND IN THE EMPLOYMENT THEREOF FOR MURAL AND OTHER DECORATIVE PURPOSES
Year: 1868

page_text: PROVISIONAL SPECIFICATION left by Edward Primerose Howard
Vaughan at the Office of the Commissioners of Patents, with his
Petition, on the 14th April 1868.-A communication from abroad
by Felix Mattei, of Florence, in the Kingdom of Italy, Engineer.
I, EDWARD PRIMEROSE HOWARD VAUGHAN, of 54, Chancery Lane,
in the County of Middlesex, Patent Agent, do hereby declare the
nature of the said Invention for "IMPROVEMENTS IN THE MANUFACTURE OF
CERAMIC TESSERE AND IN THE EMPLOYMENT THEREOF FOR MURAL AND OTHER
DECORATIVE PURPOSES," being a communication to me from abroad by
Felix Mattei, of Florence, in the Kingdom of Italy, Engineer, to be
as follows:-
This Invention consists in certain improvements in the manufacture
of ceramic tesseræ or tiles, and in the arrangement and employment
thereof for mural and other decorative purposes.
An exact copy of the design to be reproduced is transferred in its
simple outlines to a horizontal flooring by means of tracing paper or
any other analogous method either in its integrity, or if the dimensions
of the flooring do not allow this to be done by successive portions.
In making this linear drawing the division of the tesseræ must be

page_text: studied so that the seams or joints between them shall coincide with
the outlines of the Drawing, and care must be taken that no single
tessera shall be of such size as to present serious difficulties in the
successive manipulations. The contour of each tessera is transferred
on a moveable board (with sufficient enlargement to allow for shrinkage
in the drying and baking of the material) by means of a pantograph
or other suitable apparatus. All round this enlarged contour (with
a further allowance of, say, about one-eighth of an inch) a border
of plaster of Paris is raised, its inner surface being at right angles with
the board, and of such depth as the thickness the tessera may be
intended to possess. The board and plaster border thus arranged con-
stitute the mould, the tessera being formed by placing the clay therein.
In order that the tessera may be lighter than they would be if con-
structed entirely solid and that a more perfect baking may be ensured
it may be advisable to make their backs honey-combed with holes or
cells. The clay tessere thus formed are dried and baked in the usual
and well known manner, and as in such processes they must necessarily
in some degree lose shape, it is requisite to plane or smooth their
fronts by rubbing them with sand and water on a flat surface as usual
in preparing marble slabs. The contours or edges of the tessera
should also be ground to precision, and they are for this purpose placed
on the drawing floor and with the help of the pantograph or other
apparatus or means as before mentioned, the contours are engraved
with a fine point so as to mark the extent to which the edges are
to be reduced. In grinding a small allowance is left around the
tesseræ, the extent of such allowance depending on the quality of the
clay employed and whether it is more or less liable to be acted upon
at the edges during the operation of glazing. After the fronts and
edges of the tessere have been smoothed and ground, it is necessary
to give them another short firing in the kiln so as to insure their
being perfectly dry; the glaze is then put on and fired as usual, such
glaze being white or coloured as may be desired. On this glazing
the painting of the tesseræ is to be effected, putting together as much
as possible such a number of the tesseræ as may belong to a single
grouping of the composition. The colours are then fired and the tessera
are ground to their true contour so that they may be fitted together
with such precision that the interstices between their edges may be
hardly visible. This precision can be in a great degree obtained by
mechanical means in the following manner:-Any part of the contour

page_text: of each single tessera (except those round the edges of the picture)
will always be common to two of them. Supposing that the
contour common to two tesseræ, 1 and 2, has been transferred
as exactly as possible on the tessera 1 from the floor drawing and
then ground to precision, let a small chamber be formed on a flat
board with three battens of proper length and of the same thickness
as the tessere, having for its fourth sido the ground contour of
the tessera 1 on which it must fit with the tessera 2. Let the chamber
be made tight by means of a little beeswax or other suitable material
at the angles, and then let liquid plaster of Paris be poured in. When
solid the edge of the plaster mould in contact with the tessera 1 will
be of exactly the form to be given to the corresponding part of the
tessera 2. The transfer of this form from the plaster mould to the
tessera 2 is to be effected by a tool analogous to the many known
copying machines. The tessera and the plaster mould are properly fixed
on a rest travelling with a slow feed motion, a small grinding wheel
doing the work on the tessera, and a roller of exactly the same diameter
guiding its position by being pressed by a spring or counterweight
against the plaster mould.
In cases in which the ceramic painting is to be placed at a con-
siderable height or to be seen from a distance or by a subdued light
it is unimportant that the tesseræ should fit quite perfectly. In such
cases the contours of the tesseræ may be finished at once before
applying the glaze and colours, merely removing before the tesseræ
are fixed whatever parts of the glaze and colouring may have run
over the edges in the kiln.
When the tessere are completed they may be fixed either on the
usual mortar coating or on bitumen cement. In the first case it is
advisable to leave at intervals some channels, vertical or nearly so,
open at top and bottom to allow the mortar to dry, care being taken
that such channels be not placed under the corners of the tesserve.
The fixing should be commenced from the top of the painting laying
in succession such portions of the mortar or bitumen coating as may
be required for the tesseræ next to be placed.