Improvements in Etching upon Glass.
Year: 1890

page_text: COMPLETE SPECIFICATION.
Improvements in Etching upon Glass.
We, BEN ZION METH, of 6, Wollinerstrasse, Glass-worker, and HERMANN KREITNER,
of 83, Chorinerstrasse, Merchant, both in Berlin in the German Empire, 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 etching upon glass differing from the methods
hitherto employed in that the etching is effected by a cold process and with the aid of
an india-rubber stamp, the etching of such articles as bottles, lamp glasses, glass
plates, and similar objects being considerably accelerated, and the cost of treatment
reduced.
In carrying out our process, we use an etching solution prepared in the following
manner-10 grammes of pure fluoride of ammonium, a gramme of common salt, and
a gramme of carbonate of sodium are well pounded up in a porcelain mortar, and
mixed in a gutta-percha bottle with 4 grammes of highly-concentrated fuming
hydrofluoric acid and 2 grammes of concentrated sulphuric acid; the bottle being well
shaken. In a separate vessel, made of lead, a gramme of crystallized fluoride of
potash is dissolved in 1 gramme of common muriatic acid heated in a hot water bath.
Of the latter mixture, 1 gramme is added to the mixture previously prepared; the
contents of the bottle being again agitated and mixed with 2 drops of silicate of sodium
and 1 drop of spirits of sal-ammoniac.
A small quantity of the etching solution thus formed is dropped upon a sheet of
india-rubber covered with a cloth pad, which is rubbed until almost dry; whereupon,
by means of an india-rubber stamp, bearing the design to be reproduced, a portion
of the liquid previously absorbed by the pad is transferred to the surface to be etched
with the result that the design is eaten out.
Should a deposit be formed in the gutta-percha bottle in consequence of the etching
solution not having been used for some time, such deposit may be dissolved by hydro-
fluoric acid.
Having now particularly described and ascertained the nature of this invention
and in what manner the same is to be performed, we claim :-
1. In etching upon articles of glass, the employment of a solution prepared by
mixing the following ingredients substantially in the proportions herein specified;
that is to say, 10 grammes of pure fluoride of ammoniumn, a gramme of common salt,
and a gramme of carbonate of sodium, well pounded together, adding 4 grammes of
highly-concentrated fuming hydrofluoric acid and 2 grammes of concentrated
sulphuric acid, then adding 1 gramme of a mixture of a gramme of crystallized
fluoride of potash and 1 gramme of heated muriatic acid, and finally adding two
drops of silicate of sodium and one drop of spirits of sal-ammoniac.
2. The cold process for etching upon glass substantially as herein described, and
wherein the etching solution is transferred by means of an india-rubber stamp from a
pad to the article to be etched.
3. The employment, substantially as herein described, of hydrofluoric acid for
regenerating the etching solution referred to in the first of the preceding claiming
clauses.
Dated the 2nd day of Awenst 1800
G. G. M. HARDINGHAM,
191, Fleet Street, London, E., Agent for the Applicants.