Process for the Production of Colored Designs and Colored Writing on Mirrors.
Year: 1891

page_text: Date of Application, 9th June, 1891-Accepted, 11th July, 1891
הד ב-6.
Process for the Production of Colored Designs and Colored Writing
on Mirrors.
I, Dr. LEONHARD LEDERER, of Waldhof, Mannheim, Germany, 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 a process for producing colored designs on the polished
or engraved or etched surfaces of glass mirrors and consists in first coating these
surfaces with soluble metallic compounds and then acting on these with sulphuretted
hydrogen, or ammonium sulphide, or in place of metallic compounds other chemical
reagents may be used, which form compounds that are colored by means of
sulphuretted hydrogen or ammonium sulphide. The surfaces so acted upon are then
covered with metal foil.
For the above purpose the design produced on the glass by engraving or etching,
or a combination of these, is coated on those parts which are not to be colored with
a coating of varnish, the glass having been previously carefully cleaned. The
exposed glass surface is now treated uniformly with a dilute aqueous solution of
sulphate of cadmium. After evaporation of the water there is left on the glass a
very thin coating of the cadmium salt. If it is desired to produce several colors,
the solutions of the substances giving colored compounds, are applied as rapidly as
possible one after the other.
The glass surface thus prepared is then subjected to the action of sulphuretted
hydrogen, whereby the colorless cadmium sulphate is converted into yellow cadmium
sulphide.
If the layer of cadmium sulphide is now covered, by metal foil, the color will
appear as dead gold or burnished gold, according to the nature of the etching or
engraving of the glass.
The said covering is effected as follows upon the colored design. The part of
the surface which was protected by varnish having been cleared and carefully
cleaned, a foil of silver aluminium &c. is then pressed upon the colored parts by
suitable known means in such manner that no air is left between the foil and the
glass. The foil fills out the finest recesses of the design and adheres closely to the
glass surface.
In order to remove the metal extending beyond the design, it is acted upon
with a spatula of wood, horn vulcanite &c., so as to limit the metal covering
accurately to the design. The entire glass surface is then carefully cleaned again,
and is silvered all over in the usual manner.
Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed, I declare that what I
claim is:
1. A process for producing coloured designs or writing on the polished, engraved,
or etched glass surfaces of mirrors by the action of sulphuretted hydrogen or
ammonium sulphide upon a coating or film of soluble metallic compounds or other
reagents forming compounds that are colored by the action of sulphuretted hydrogen
or ammonium sulphide, substantially as described.
2. Covering the glass surface coated with a colored film or coating as set forth in
the preceding claim, with metal foil, substantially as described.
Dated this 9th day of June 1891
ABEL & IMRAY,
Agents for the Applicant.