Improved Processes for Coating Aluminium or other Metals with Silver or other Metals.
Year: 1897

page_text: Improved Processes for Coating Aluminium or other Metals with
Silver or other Metals.
We, GASTON WEIL, ALFRED LEVY, being both Chemists, and living both at 24, Rue
St. Lazare, in Paris, do hereby delare the nature of this invention to be as
follows:-
:-
We claim as our own process the means we are going to describe of silvering
gilding, coppering, nickelling, &c. aluminium, it being understood that we reserve
to ourselves the right of applying the same to silvering gilding coppering nickelling
&c. any other metal.
We have discovered that if a product which belongs to the class of the so called
photographic developers, such as hydroquinone, pyrocatechin, pyrogallic acid &c.
is added to an ordinary bath for silvering, gilding, coppering, nickelling &c., this
bath which before said addition could not silver gild &c. aluminium, does perfectly
metallize aluminium after above mentioned addition has been made.
It is by
strongly alcalinizing the thus modified baths that we obtained the best results"
however we intend to reserve to ourselves the right of using neutral or acid baths
modified in the same way through addition of one or several of the above mentioned
productions and among these productions we will particularly mention:
Pyrocatechin, hydroquinone,
Pyrogallic acid and pyrogallates
Gallic acid and gallates
Tannic acid and tannates
Oxalic acid and oxalates
Tartaric acid and tartarates
Lactic acids and lactates.
But again and besides the above said productions we claim as our own property any
process of metallization which would consist in the addition to an electro-chemical
bath of any production susceptible of ranging in the category of photographic
developers since it was shown by our experiments that any production of this kind
may under certain circumstances give favourable results. We reserve to ourselves
the right of using our baths either warm or cold and simply through the simple
dipping process or by means of an electric current. We more especially use
hydroquinone or lactic acid for silvering baths and and pyrogallic acid for coppering
baths.
་
By means of our process we can directly metallize aluminium as well as we
can do it after previous coppering. In both cases we deposit heavy coatings of
metal, which coatings are perfectly adherent, since the objects so coated stand
thoroughly well the burnishing operation, and still more that of polishing.
By coppering aluminium we are enabled to goldplate or silverplate it through
such means as are used in similar cases.
In short we claim of our own property.

page_text: 1°. The silvering gilding coppering nickelling &c. of aluminium or any other
metal by adding to any bath for silvering gilding coppering nickelling &c. one or
several productions belonging to the category of the so called photographic
developers and more especially the following productions:
Pyrocatechin, hydroqinone
Pyrogallic acid and pyrogallates
Gallic acid and gallates
Tannic acid and tannates
Oxalic acid & oxalates
Tartaric acid and tartarates
Lactic acids and lactates
These baths being used either cold or warm through a simple dipping process or
with an electric current.
2°. More especially the use of hydroquinone or lactic acid for silvering baths and
pyrogallic acid for coppering baths being strongly alcaline though they may be
likewise neutral or acid, applied cold or warm by means of a simple dipping process
or of an electric current.
3°. The gold or silver plating of previously coppered aluminium.
Improved Processes for Coating Aluminium or other Metals with
Silver or other Metals.
We, GASTON WEIL and ALFRED LEVY, both of 24, Rue St. Lazare, Paris, in the
Republic of France, Chemists, do hereby declare the nature of this invention and
in what manner the same is to be performed, to be particularly described and
ascertained in and by the following statement :-
This invention relates to improved processes in the art of electro-plating its
object being the electro-deposition on aluminium of a perfect coating of silver or
of copper. Although specially adapted for the coating of aluminium the processes
are applicable to the coating of other metals.
In carrying out our invention we employ baths composed of metallic and alkali
salts to which has been added one of certain definite substances belonging to the
class of so-called photographic developers, viz.: hydroquinone, pyrocatechine or
pyrogallate or gallate of ammonia.
For coating with silver we nienare a bath of

page_text: or this may be replaced by an equal amount of gallate of ammonia.
This bath may be used hot or cold; preferably a temperature of about 100° Fh.
is employed.
The article to be coated is prepared and treated in the manner usually employed
in the electro-plating art.
The best results are obtained with alkaline baths as described, but these may be
rendered either neutral or acid by means of organic acids such as gallic or tartaric
acid etc.
Although the quantities given above are those which are found to afford the best
results in practice we do not bind ourselves to the exact proportions which may be
slightly varied.
Having now particularly described and ascertained the nature of the said
invention and in what manner the same is to be performed, we declare that what we
claim is:
1. In the electro-deposition of metals the employment in an electrolytic bath of
hydroquinone or of pyrocatechine.
2. In the electro-deposition of silver or copper on aluminium or other metals the
employment of baths composed substantially of the ingredients and in the
proportions specified.
BOULT & WADE,
Agents for the Applicants.