AN IMPROVED PROCESS OF GILDING AND PRO
Year: 1856

page_text: LETTERS PATENT to Alexandre Henri Dufresne, of 39, Rue de l'Echiquier,
Paris, in the Empire of France, and of 4, South Street, Finsbury,
London, for the Invention of "AN IMPROVED PROCESS OF GILDING AND
PROVISIONAL SPECIFICATION left by the said Alexandre Henri Dufresne
at the Office of the Commissioners of Patents, with his Petition, on the
21st May 1856.
I, ALEXANDRE HENRI DUFRESNE, of 39, Rue de l'Echiquier, Paris, in the
Empire of France, and of 4, South Street, Finsbury, London, do hereby
declare the nature of my Invention for "AN IMPROVED PROCESS OF GILDING AND
ORNAMENTING STEEL AND OTHER METALS," to be as follows, that is to say:-
My Invention consists, first, in the employment of mercury and heat for the
application of gold and silver on metals that cannot be amalgamated.
Secondly, in the employment of photographic processes or impressions for
making the reserves.
Thirdly, in removing the copper with chromic acid without deteriorating.
even the polish of the iron.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Alexandre Henri Dufresne in the Great Seal Patent Office
on the 20th November 1856.
.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, ALEXANDRE
HENRI DUFRESNE, of 39, Rue de l'Echiquier, Paris, in the Empire of France,
and of 4, South Street, Finsbury, London, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Twenty-first day of May, in the year of our Lord
One thousand eight hundred and fifty-six, in the nineteenth year of Her
reign, did, for Herself, Her heirs and successors, give and grant unto me, the
said Alexandre Henri Dufresne, Her special license that I, the said Alexandre
Henri Dufresne, my executors, administrators, and assigns, or such others as
I, the said Alexandre Henri Dufresne, 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 1
Britain and Ireland, the Channel Islands, and Isle of Man, an Invention
for "AN IMPROVED PROCESS OF GILDING AND ORNAMENTING STEEL AND OTHER
METALS," upon the condition (amongst others) that I, the said Alexandre Henri
Dufresne, by an instrument in writing under my hand and seal, should par-
ticularly 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 Alexaudre Henri Dufresne, do hereby
declare the nature of my said Invention, and in what manner the same is to
be performed; to be particularly described and ascertained in, and by the
following statement thereof, that is to say:
My Invention relates to the gilding, silvering, and ornamenting of metals
not susceptible of direct amalgamation; and consists, first, in the employment
of one or several: intermediate: metals, deposited eitlier by chemical, electro-
chemical, or mechanical processes, on the metal to be gilded, silvered, or
ornamented.
Secondly, in the manual or mechanical application of a protecting miatter,
such as varnish, bitumen of Judea, printers' ink, &c., upon the intermediate
'metals, to form the reserves to be gilded, silvered, or ornamented, such reserves
being produced by photographic means, or by a general coating sensible to light,
such as bitumen of Judea.

page_text: Thirdly, in the destruction of the intermediate unreserved metals, by baths of
different kinds, such as ammonical or acid solutions, applied so as to preserve
the polish, or to act on the surface of the metal to be gilded, silvered, or
ornamented, for the production of flat and relievo designs.
Fourthly, in the removal of the protecting matters which have served to
preserve the surfaces operated on.
Fifthly, in gilding or silvering the surfaces by means of mercury, according
to the ordinary processes of gilding and silvering by amalgamation, and finally.
the volatilisation of the mercury by heat.
Having thus described the nature of the Invention, I will now proceed to
describe the mode of carrying it into effect, premising that the working details
may be modified according to the metals on which the deposit is to be effected,
and other varying circumstances.
To operate on iron or steel, a coating of copper is deposited on one of these
metals selected, which is then gilded or silvered by the ordinary processes of
amalgamation, if it is intended to cover the entiro surface. To decorate or
damaskeen either of these metals with designs in gold or silver on the iron or
steel grounds, or vice versa. I cover entirely the metal to be operated upon
with a coating of copper by the ordinary means. On the copper surface thus
prepared I form the required design by means of varnish, bitumen of Judea, or
other suitable protecting substances, and then immerse the article in a bath of
chromic acid, which dissolves the portions of the copper unprotected by the
varnish, leaving intact the surface of the iron or steel. The varnish is then
removed by means of a hot turpentine, exposing thus a design in copper on
the iron or steel ground. The article is then finished off and the gilding or
ornamenting of the design effected, the mercury being volatilised by heat after
the amalgamation in the ordinary way.
:
To operate on platina, I cover entirely with copper the article to be orna-
mented, and then form the design, as before stated. The unprotected parts of
the copper are then dissolved out by nitric, sulphuric, chromic, or other suitable
acid, and the varnish being removed, I gild or ornament by amalgamation as
for iron.
To operate on silver, the processes are in this case modified, as follows:--I
deposit on the silver surface a triple metallic coating thus:-first, copper;
second, iron; third, a second surface of copper. I form the reserves on this
last coat of copper, and then destroy in succession the unreserved parts of the
superposed metals, so that the iron which presents itself, on removal of the
upper coat, prevents the mercury from adhering to the first copper or silver
surface during the amalgamation. The iron is lastly removed by any suitable

page_text: re-agent. The object of interposing the iron between the two copper surfaces
is to facilitate and shorten the operation, by limiting the employment of the
reserves to the surfaces to be gilded or ornamented. (By the present mode of
operation the entire ground is protected.) This object is effectually attained
by the agency of chromic acid, which readily dissolves the copper without
effecting the iron surface to the slightest extent. Instead of interposing an iron
coating between two coats of copper, I can employ, and in most cases more
advantageously, a surface of nickel or antimony, which are readily acted on by
chromic acid. In this case I remove the last surface of copper by an
ammoniacal solution, which has the advantage of leaving the silver untouched.
These intermediate metals may, however, vary according to circumstances.
Instead of forming the reserves by the hand by means of protective varnishes,
I can employ the ordinary processes of photography, heliography, or impression,
either directly or by transfer on the surface to be gilded, silvered, or orna-
manted, and am thus able to reproduce in the metallic state the most
complicated arabesques and designs.
Having now described the nature of my said Invention, and the most con-
venient manner of carrying the same into effect, I wish it to be understood
that I do not confine myself to the precise working details herein laid down,
as the same may be modified according to the requirements of cach operation
without departing from the principle of the Invention; but what I claim
is,
First, the application of gold and silver to metals incapable of direct
amalgamation, by means of the processes herein-before described.
Secondly, the employment of photographic, heliographic, and printing pro-
cesses, for the production of the reserves on the metallic surfaces, to be.
operated on by the means herein-before described.
Thirdly, the use of chromic acid for the destruction of the nickel, copper,
antimony, or other metal employed in these processes, as herein-before:
described.
In witness whereof, J, the said Alexandre Henri Dufresne, have here-
unto set my hand and seal, this Fifteenth day of November, in
the year of our Lord One. thousand eight hundred and fifty-six.
A. HENRY DUFRESNE. (L.S.)