IMPROVEMENTS IN GILDING ARTICLES OF METAL
Year: 1880

page_text: LETTERS PATENT to Alexander Melville Clark, of 53, Chancery Lane, in the
County of Middlesex, Patent Agent, for an Invention of "IMPROVEMENTS IN
GILDING ARTICLES OF METAL." A communication from abroad by Gabriel
François Louis, Counto de Chastenet d'Esterre, Administrateur Délégué de la.
Société Française d'Inoxydation et de Platinage, of Paris, France.
PROVISIONAL SPECIFICATION left by the said Alexander Melville Clark
at the Office of the Commissioners of Patents on the 17th February 1880.
ALEXANDER MELVILLE CLARK, of 53, Chancery Lane, in the County of
Middlesex, Patent Agent. "IMPROVEMENTS IN GILDING ARTICLES OF METAL."
[A communication from abroad by Gabriel François Louis, Comte de Chastenet
d'Esterre, Administrateur Délégué de la Société Française d'Inoxydation et de
Platinage, of Paris, France.]
This Invention consists in coating metals with a very light but very strong
covering of gold presenting a very rich appearance, a bright or lustrous surface
being obtained without having recourse to burnishing.
Product No. 1.—I dissolve 1 kilogramme of pure alum in a sufficient (but the
least possible quantity of water); after it is completely dissolved I pour in 1 litre
of ammonia (alkali), whereby the alum is precipitated in the form of a very thick
jelly. This precipitate is then placed on a filter in order to drain off as much of
the water as possible. The alum is then put into a porcelain capsule and I add
500 grammes of nitric acid, which has the property of redissolving the alum.
1 then dissolve in another capsule 150 grammes of carbonate of cobalt in 200
grammes of nitric acid; I assist the solution by the gentle heat of a sand bath.
When the solution is complete I pour it upon the alum solution; the whole being
well mixed I completely evaporate the acids by placing the capsule in a highly
гр.

page_text: heated sand bath. I collect and pound the product, and calcine it in a crucible
over a strong fire before employing it in the following composition:-
Product No. 2.-I melt the following composition well mixed in a crucible over
a quick fire :-
kil
When melted I run the product into cold water, I dry, and then grind the product
by the processes now. employed for grinding enamels. The product is ground up
with spirits of turpentine, and it should be ground as fine as possible in order to
facilitate its employment; if too thick a suitable quantity of turpentine is added.
Product No. 3. I dissolve in a porcelain capsule—
Pure gold
Muriatic acid
Nitric acid
100 gr.
200
כן
100 "
1
I assist the solution by the moderate heat of a sand bath, and I then add
2 grammes of pure tin and 2 gramines of arsenious acid. I then evaporate about :
one half of the acids, I let cool, and add 150 grammes of distilled water. The
solution is put on one side and the following operation proceeded with :-
Product No. 4.-I put in a glass matrass 150 grammes of turpentined balsam
of sulphur containing 20% of sulphur (such as prepared by all druggists),
40 grammes of Venice turpentine, 200 grammes of essential oil of lavender. "I heat!
in a sand bath until the liquid has attained a deep red color. At this point
I remove from the fire and let cool. After cooling I pour the whole into a
porcelain capsule, and then pour in product No. 3 very slowly, taking care to well
stir continually the product No. 4 with a glass spatula. In this operation I employ
assistance for pouring and stirring, as it is very difficult to pour slowly with one
hand and stir well with the other.
When No. 3 is poured in there forms in capsule No. 4 a material of a very rich
brown color, and which becomes very thick. If the desired tint does not at once
appear I slightly beat the matter, continuing the stirring all the while, and with-
draw it from the fire directly I perceive the change of color take place, whereupon
I allow it to cool as the gold has now left the ncids.
After cooling I remove the acids as carefully as possible and let stand until the
next day; I then again remove any little acid which may have separated from the
product, and then, without troubling myself about any it may still contain, I pour
upon it drop by drop, taking care to stir well the while, and so long as any reaction
can be perceived, 50 grammes of ammonia (alkali) (this quantity is not always
necessary.
The mixture is very readily effected and I allow it to rest for 2 hours, after
which I pour in 300 grammes of essential oil of lavender. I heat slightly in order
to mix thoroughly and then let cool; I then filter the product through paper, which
I take care to immerse in essential oil of lavender in order to render it impervious
to water.
The auriferous liquor passes through while the ammoniacal water remains on the
filter. The product so obtained is ready for use on leaving the filter.
Many other processes for obtaining gold in this form have been described and
applied to porcelain, pottery, and glass ware, but they are not suitable for
application to metals. It is not however this formula that I have the intention to
Patent, but the application of bright gilding without polishing or burnishing, or of
matt gilding on metals by means of baths, or the application with a brush of gold,
"

page_text: either alloyed or pure, held in suspension or solution in fatty bodies or essential
oils according to the requirements of the application.
For bright gilding on wrought or cast iron, copper, and other metals I proceed
as follows: The articles to be gilded should be very clean, that is to say, free
from oxidation or foreign matters; the articles in this condition are slightly
heated to remove moisture, and I then proceed by dipping a brush in product No. 2
and coating the articles therewith, taking care to apply to all parts a sufficiently
thick coat, which should be about as thick as a rather heavy coat of oil paint. The
articles thus coated are placed in a cupboard to shelter them from dust, and left for
a few hours to dry, after which they are heated in a muffle similar to that employed
by enamellers, or of a size suited to that of the articles to be operated on. On
leaving the muffle the articles present brilliant blue black aspect. When cooled
the articles thus treated are ready for gilding, which is effected by dipping a
brush in the gold liquor No. 4, and applying a very light and very even coat of
it to the articles. I then allow them to dry for a few hours in a situation
sheltered from dust, after which I proceed to heat the gold in the same manner
as for product No. 2, taking care to heat them slowly in order to prevent the
blistering of the gold layer. The transformation is then seen to take place, the
articles passing from the black tint to a brilliant yellow, and at this moment
they should be removed from the muffle. The beauty and solidity of this gilding
will be at once apparent, it being much superior to electro or mercurial gilding.
For matt gilding it is only necessary that the coating of No. 2 should be very
thin in order that it may remain matt, as the lustre is only due to the thickness of
the layer. As the articles remain matt the gilding will be also matt.
If desired to obtain bright gilding without using product No. 2, it may be done
by polishing the articles beforehand, either by hand tools or in a lathe in the
ordinary way. The gold applied to polished metals is also brilliant, but it requires
to be laid on much thicker in the case of cast iron on account of its porosity.
A matt surface may be similarly produced upon the metal direct, but it is always
preferable to use product No. 2, as three fourths less gold are required than when
applied to the metal direct.
It will be seen from the foregoing that the process is at once simple and
economical.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Alexander Melville Clark in the Great Seal Patent Office on the 17th
August 1880.
ALEXANDER MELVILLE CLARK, of 53, Chancery Lane, in the County of
Middlesex, Patent Agent. "IMPROVEMENTS IN GILDING ARTICLES OF METAL"
A communication from abroad by Gabriel François Louis, Comte de Chastenet
d'Esterre, Adininistrateur Délégué de la Société Française d'Inoxydation et de
Platinage, of Paris, France.
This Invention consists in coating metals with a very light but solid covering of
gold presenting à very rich appearance, a bright or lustrous surface being obtained
Product No. 1. I dissolve one kilogramme of pure alum in a sufficient (but the
least possible) quantity of water; after it is completely dissolved I pour in 1 litro
of ammonia (alkali), whereby the alum is precipitated in the form of a very thick
jelly. This precipitate is then placed on a filter in order to drain off as much
of the water as possible. The alum is then put into a porcelain capsule and
I add 500 grammes of nitric acid, which has the property of redissolving the alum.
I then dissolve in another capsule 150 grammes of carbonate of cobalt in 200
grammes of nitric acid; I assist the solution by the gentle heat of a sand bath.
When the solution is complete I pour it upon the alum solution; the whole being
well mixed I completely evaporate the acids by placing the capsule in a highly
heated sand bath. I collect and pound the product, and calcine it in a crucible
over a strong fire before employing it in the following composition :-
Product No. 2.-1 melt the following composition well mixed together in a
crucible over a quick fire :-

page_text: For bright gilding on wrought or cast iron, copper, and other metals I proceed as
follows: The articles to be gilded should be very clean, that is to say, free from
oxidation or foreign matters; the articles in this condition are slightly heated to
remove moisture, and I then proceed by dipping a brush in product No. 2 and
coating the articles therewith, taking care to apply to all parts a sufficiently thick
coat, which should be about as thick as a rather heavy coat of oil paint. The
articles thus coated are placed in a cupboard to shelter them from dust, and left for
a few hours to dry, after which they are heated in a muffle similar to that
employed by enamellers, or of a size suited to that of the articles to be operated on.
On leaving the muffle the articles present a brilliant blue-black aspect. When
cooled the articles thus treated are ready for gilding, which is effected by dipping a
brush in the gold liquor No. 4 and applying a very light and very even coat of it
to the articles. I then allow them to dry for a few hours in a situation sheltered
from dust, after which I proceed to heat the gold in the same manner as for
product No. 2, taking care to heat slowly in order to prevent the blistering of the
gold layer. The transformation is then seen to take place, the articles passing from
the black tint to a brilliant yellow, and at this noment they should be removed
from the muffle. The beauty and solidity of this gilding will be at once apparent,
it being much superior to electro or mercurial gilding.
Fer matt gilding it is only necessary that the coating of No. 2 should be very
thin in order that it may remain matt, as the lustre is only due to the thickness of
the layer. As the articles remain matt the gilding will be also matt.
If desired to obtain bright gilding without using product No. 2, it may be done
by polishing the articles beforehand, either by hand tools or in a lathe in the
ordinary way. The gold applied to polished metals is also brilliant, but it requires

page_text: to be laid on much thicker in the case of cast iron on account of its porosity.
A matt surface may be similarly produced upon the metal direct, but it is always
preferable to use product No 2, as three-fourths less gold are required than when it
is applied to the inetal direct. It will be seen from the foregoing that the process
is at once simple and economical.
Having described the nature of the said Invention and the manner of performing
the same, 1 declare that what I claim as the Invention to be protected by tho
hereinbefore in part recited Letters Patent is,—
The improved process of bright gilding or matt gilding on cast or wrought iron
and other metals with a gold liquor.applied by means of a bath or brush, as
herein before described.
In witness whereof, I, the said Alexander Melville Clark, have hereunto set
my hand and seal, this Seventeenth day of August, in the year of our Lord
One thousand eight hundred and eighty.
A. M. CLARK. (L.S.)