IMPROVE- MENTS IN MAKING MOULDS FOR CASTING METALS
Year: 1866

page_text: LETTERS PATENT to John Fisher, of No. 3, Little Tower-Street, in the
City of London, Mechanical Engineer, for the Invention of "IMPROVE-
MENTS IN MAKING MOULDS FOR CASTING METALS."- A communication from
. abroad by Hadji Jappa, of Singapore.
PROVISIONAL SPECIFICATION left by the said John Fisher at the Office
of the Commissioners of Patents, with his Petition, on the 26th
October 1866..
'I; JOHN FISHER; of No. 3, Little. Tower Street, in the City of London,
Mechanical Engineer, do hereby declare the nature of the said Invention for
IMPROVEMENTS, IN. MAKING MOULDS FOR CASTING METALS," to be as follows:-
The said Invention consists of the. improvements herein-after described in
making moulds for: casting metals, by which said improvements articles in
metal of a complex figure, and which cannot, be cast in moulds of the ordinary
kind, may be readily cast.
In making a mould-for-casting-metals-according to the said Invention I
proceed as follows:-I take a model of the article to be cast in metal, the
said model being made of wax or other material or mixture of materials which

page_text: will fuse at a moderate heat; I also take a mixture of clay, sand, and char-
coal, tempered with water, so as to be very plastic and capable of readily
taking the impression of the model. The model in wax is covered with a
layer of the said plastic mixture, which layer is allowed to dry spontaneously;
a second layer of the said plastic material is put upon the first, and so on,
untill the layers have accumulated to a degree sufficient to give the required
strength to the mould. The outer layers may be put on thicker than the
inner one and a coarser material may be employed for the said outer layers.
After the mould has sufficiently dried the required gets for the introduction
of the melted metal and the required vents for the escape of air and gases are
made in the moulds. Before the mould is used it is thoroughly dried and
heated nearly to redness. By this treatment the model is melted out and
the mould is ready for the casting process. The drying of the mould after
the application of each layer of the plastic mixture may either be by the
spontaneous evaporation of the water or by the application of a gentle heat.
*SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said John Fisher in the Great Seal Patent Office on the 22nd
April 1867.
TO ALL TO WHOM THESE PRESENTS' SHALL COME, I, JOHN
FISHER, of- No. 8, Little Tower Street, in the City of London, Mechanical
Engineer, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria; by Her Letters
Patent, bearing date the Twenty-sixth day of October, in the year of our
'Lord One thousand eight hundred and sixty-six, in the thirtieth year of Her
'reign, did, for Herself, Her heirs and successors, give and grant unto me,
the said John Fisher, Her special licence that I, the said John Fisher, my
executors, administrators, and assigns, or such others as I, the, said John
Fisher, my executors, administrators, and assigns, should at any time agree
with, and no others, from time to time and at all times thereafter during
the term therein expressed, should and lawfully might make, use, exercise,
and vend, within the United Kingdom of Great Britain and Ireland, the
Channel Islands, and Isle of Man, an Invention for "IMPROVEMENTS IN
MAKING MOULDS FOR CASTING METALS," a communication to me from abroad by
Hadji Jappa, of Singapore, upon the condition (amongst others) that I, the
'said John Fisher, my executors or administrators, by an instrument in writing
-under my, or their, or one of their hands and seals, should particularly

page_text: describe and ascertain the nature of the said Invention, and in what manner
the same was to be performed, and cause the same to be filed in the Great
Seal Patent Office within six calendar months next and immediately after
the date of the said Letters Patent.
. NOW KNOW YE, that I, the said John Fisher, do hereby declare the
nature of the said Invention, and in what manner the same is to be per-
formed, to be particularly described and ascertained in and by the following
statement thereof, that is to say :-
The said Invention consists of the improvements herein-after described in
making moulds for casting metals, by which said improvements articles in
metal of a complex figure, and which cannot be cast in moulds of the
ordinary kind, may be, readily cast.
clay, charcoal, and sand, tempered
capable of readily taking the im-
is covered with a layer of the said
dry spontaneously; a second layer
. In making a mould for casting metals according to the said Invention I
proceed as follows:-I take a model of the article to be cast in metal, the said
model being made of wax or other material or materials which will fuse at a
moderate heat; I also take a mixture of
with water, so as to be very plastic and
pression of the model.. The model in wax
plastic mixture, which layer is allowed to
of the said plastic mixture is put upon the first, and so on, until the layers
have accumulated to a degree sufficient to give the required strength to the
mould. The outer layers may be put on thicker than the inner one, and a.
coarser material may be employed for the said outer layers. After the mould
has sufficiently dried the required" gets". for the introduction of the melted
metal and the required vents for the escape of air and gases are made in the
mould. Before the mould is used it is thoroughly dried and heated nearly to
redness. By this treatment the model is melted out, and the mould is ready
for the casting process. The drying of the mould after the application of each
layer of the plastic mixture may either be by the spontaneous evaporation of
the water or by the application of a gentle heat. When a casting having a
very smooth surface is required I prefer to make the first coating on the wax.
model of a mixture of equal parts of quartz sand, bone ash, plumbago, and
wood charcoal, all ground very fine and mixed to the consistence of cream with
water. The after coatings may be made with the mixture herein-before
described.
Having explained the nature of the said Invention I will proceed to describe
in detail-the manner in which it is carried into effect.
I prefer to apply the moulding material to the wax.model in the following
manner: I first take, the, wax or other model and apply thereto a coating of

page_text: blacklead; this coating answers two purposes, first, it destroys the transparency
of the wax and enables the model to be more perfectly finished, and also-gives
a smooth surface to the interior of the mould afterwards formed; I then take a
mixture of quartz, sand, charcoal, bone ash, blacklead, clay, and water, in
about equal quantities, and finely sift them and mix them to the consistence of
ordinary paint; this mixture is applied to the model with a brush and allowed
to dry. It is impossible to lay down any exact quantities for these materials,
as they will have to be varied according to the more or less adhesiveness of
the clay used, and the size, thickness, and mixture of metal to be afterwards
cast in the mould. These particulars are easily learned by practice; the
heavier and greater the thickness the casting has the more gas is evolved in.
casting, and the more ventilation the mould requires. After the coating
which has been applied with the brush is dry I take a mixture of clay,
charcoal, sand, and water, and mix it to about the consistence. of paste or
brickmakers' clay, and apply it on the said coating; this second coating should
be applied in small quantities and pressed on piece by piece, so as to prevent
any air being left between the two coatings; this coating should not exceed
one-quarter or. three-eighths of an inch in thickness. When thoroughly
coated in this way the mould is set aside to dry slowly; when dry, another
coating of the same material is applied, the sand employed in this coating
being coarser than that employed in the previous coating, to allow of a more
free ventilation; but before applying the last-mentioned coating I take hoops
of iron, or wire, or bent strips of the same, and apply them loosely on or
about the mould on the top of the former or second coating in order to.
strengthen the mould; these hoops or strips of iron act as a system of bond
irons, and may be varied in strength and form to suit the shape and size of the
mould; this third coating is laid over and about these bonds and makes the
mould very strong when dried. The outer coatings of the mould may be
pricked before they set with a pointed tool to make a series of small passages,
through which the gaseous matters evolved during the casting process may
readily escape.
When moulds for casting bronze, brass, or copper are to be made I
prefer to make the models of pure wax, which can be used over and
over again with a slight loss.
When several castings are required the wax models may be made by
casting the wax in moulds, instead of being modelled by the ordinary
modelling process. The moulds I prefer to employ for this purpose are
elastic moulds of india-rubber, gutta percha, or gelatine, when the model has
a complex figure and will not leave a rigid mould. When the model will.

page_text: 5
leave a rigid mould I employ moulds of copper made by the electro-
metallurgical process, or moulds of plaster of Paris. In cases where the wax
models are made by casting the original model may either be made of wax, or
metal, or other material. From the original model the elastic or other moulds
for making the wax models are prepared, and the wax models made by the
casting process are treated as berein-before described for the preparation of
moulds for casting metals.
Metal is run and cast in moulds made according to the said Invention in
the same way as it is run and cast in ordinary moulds. After the metal has
solidified and cooled the mould is broken from off the casting, and the materials
may be re-ground and combined with a fresh quantity of clay and used for
making another mould.
Having now described the nature of the said Invention, and the manner
in which the same is to be performed, I wish it to be understood that I do
not limit myself to the precise details herein described, as the same may be
varied without departing from the nature of the said Invention; but I claim
as the said Invention the improvements in making moulds for casting metals,
substantially as herein-before described, that is to say, making moulds for
casting metals by making a model of the article to be cast in wax or other
material or mixture of materials which will fuse at a moderate heat, coating
the said model in the manner described, and after drying and hardening the
mould thus made melting the model out of it, so as to leave the mould empty
ready for casting the metal therein.
In witness whereof, I, the said John Fisher, have hereunto set my hand
and seal, this Eighteenth day of April, in the year of our Lord One
thousand eight hundred and sixty-seven.
Witness,
GEORGE SHAW.
JOHN FISHER. (L.S.)