IMPROVEMENTS IN THE PREPARATION OF GLASS AND OTHER SURFACES TO BE ORNAMENTED OR TREATED BY MEANS OF THE SAND BLAST, AND IN SUBSTANCES TO BE USED THEREFOR.
Year: 1877

page_text: PROVISIONAL SPECIFICATION left by Gerard Wenzeslaus von Nawrocki
at the Office of the Commissioners of Patents on the 22nd June 1877. (A
communication from Robert Johannes Gaedicke, of Berlin.)
GERARD WENZESLAUS VON NAWROCKI, of the Firm of J. Brandt and G. W.
v. Nawrocki, of Berlin, in the German Empire, Engineers and Patent Agents.
"IMPROVEMENTS IN THE PREPARATION OF GLASS AND OTHER SURFACES TO BE
ORNAMENTED OR TREATED BY MEANS OF THE SAND BLAST, AND IN SUBSTANCES
TO BE USED THEREFOR.' (A communication from Robert Johannes Gaedicke, of
Berlin aforesaid.)
"
"
The sand blast process has of late years been applied to the production of
frosted patterns on glass, the guide pattern made of paper, gelatine, or other material
being pasted to the glass, and the so prepared surface being exposed to the sand
blast, which thus acting on the parts not covered produces a frosted surface
thereon.
It is evident that the preparation and application of these guide patterns involves
some time and expense, wherefore small and complicated patterns such as of tulle or
lace are almost out of question. Moreover, for every repetition of the pattern a
fresh paper guide pattern has to be cut out, so that even when reproducing the
same article in great quantities no saving in wages is attained. It has been proposed
by means of different templates, or stencil plates, and different colours and mixtures,
to paint the pattern on the glass and then expose it to the sand blast, but the
experiments in this direction have not been practically successful, as the blast also
affected and wore away the parts so painted.
According to this present Invention a pattern colour is composed and prepared as
follows: About 50 grammes gelatine are steeped in water for about 6 minutes;
it is then allowed to trickle off in drops. The gelatine is then put into a porcelain
vessel, which is placed into a water bath; about 50 cube centimeter of a chlorzin
solution of about 52° Beaumé are then poured over it. The gelatine being completely
solved, about 50 cube centimeter glycerin of 25° B. are added and well stirred;
thereupon about 225 grammes of Swedish lamp black are worked into the mixture.
The mass is then left on the water bath till the steeping water of the gelatine has
evaporated, and a tough pasty mass is obtained.
When dried in the air it becomes an elastic india-rubber-like substance, easily
soluble in water, and not in any sensible degree attacked by the sand blast. For
I Price 971

page_text: the templates or stencil plates, ordinary varnished stencil paper may be used, which
is smeared over on the back with a mixture of copal and wax in benzine, in order
by the stickiness of this mixture to prevent the stencil paper from shifting on the
smooth glass surface.
The stencil paint is so thick and tough that it cannot be painted on with a brush,
but must be put on with a knife or spatula.
The stencil plate having been removed, the ornamented surface is sprinkled over
with tale and wiped evenly over with cotton wool, or a soft brush, in order to prevent
any damage to the still soft drawing. In the course of a few hours the paint is,
however, so hard that it may be exposed to the sand blast. The frosting being com-
pleted, the paint is washed off with cold water.
Instead of the aforesaid 50 cube centimeter chlorzine solution of 52° Beaumé for
the mixture, a suitable quantity of nitric or acetic acid may be substituted. The
chlorzine solution is however preferred, as it has no deleterious qualities, such as
the nitric or acetic acid, in dissolving the paper of the stencil or in hurting the skin
of the workman's hand.
By the use of this Invention the most complicated drawings can be transferred to
glass by means of templates or stencil plates, and thus many glass plates can be
made all with the same pattern and all exactly alike, which has heretofore, by the
ordinary mode of pasting on, been impossible.