Improvements in the Manufacture of Bronze Printing Materials.
Year: 1899

page_text: Date of Application, 17th Nov., 1899 -Accepted, 23rd Dec., 1899
COMPLETE SPECIFICATION.
Improvements in the Manufacture of Bronze Printing Materials.
I, LUDWIG BURGER, of Schweinfurt-on-Main, Bavaria, Germany, Merchant,
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:
-
Existing bronze printing materials (hereinafter called colours) present the
grave disadvantage that they do not yield prints having the metallic lustre
desired, as is attained, for example, with prints that are produced by the old
dry process. The existing bronze printing colours become spoilt in the mix-
ing so that with them it is absolutely out of the question to obtain a print with
a metallic lustre. This is due to the fact that in the existing manufacturing
processes the substances that are mixed together, destroy the lustrous metallic
particles-that is to say, these substances coat the said metallic particles with
a layer of oxide-so that however great may be the care taken during the print-
ing process, a lustrous print in bold relief and having sharp contours can never
be obtained.
These defects are completely obviated by means of this invention, by means
of which a bronze printing colour can be produced that is both durable and
easy to work.
Prints produced with bronze printing-colours manufactured according to this
invention possess the full lustre of the bronze powder employed and the impres-
sions are exceedingly durable.
The process is substantially as follows:-1 gramme of soft mutton suet is
mixed with 04 to 05 gramme of linseed oil; the mixture thus produced is then
heated until it becomes thinly liquid. Then metallic bronze-powder is mixed
in with constant stirring, sufficient bronze-powder being added to make the
mixture rather thick. After this about 015 to 02 gramme of thickened lin-
seed oil, according to the proportions given above, is added very gradually and
thoroughly mixed. The bronze printing colour produced in this way may be
ground on the stone by means of colour rollers and worked like any other print-
ing-colour.
The thickened linseed oil may be mixed with the mutton-suet first of all so
that the process will be as follows: A gramme of soft mutton suet is heated
with 035 gramme of thickened linseed oil until the mixture has become a thin
liquid. Then bronze is stirred in until the mixture assumes a pulpy consistency.
The following process has, however, shown itself to be the best:-
About 250 grammes of a solution of copal or amber in linseed oil in the pro-
portion of 1 gramme of copal or amber to about 8 to 10 grammes of linseed oil,
are melted thoroughly together with 200 grammes of tallow and 80 grammes
of olein. Instead of olein, parathin oil or castor oil may be used.
To this warm
thin-fluid mass bronze powder is now added until the mixture attains a pulpy
consistency. After the mixture has almost completely cooled down, about
80 grammes of linseed oil, thickened by boiling, is very gradually added thereto
and mixed therewith.

page_text: The bronze printing-colour obtained in this way is exceedingly durable and
exhibits a fine metallic lustre, so that printing carried out with it can scarcely
be distinguished from that done by the dry process.
The percentage composition depends entirely on the quality of the raw
material, and especially on the softness of the tallow and the nature of the
linseed oil.
In order to facilitate the working of the bronze printing-colour produced in
this way there may be added to the same a diluent consisting of copal or amber,
tallow, linseed oil, and olein, paraffin oil, or castor oil in the same proportions
as the said substances have in the mixture to which the diluent is to be added.
Instead of the tallow herein before mentioned, stearine, palmitin, or bone-fat
may be used in suitable proportions. Likewise a mixture of true silver or gold
bronze with a printer's varnish or any other suitable oil, as for example, one
of those used in the process herein before described, yields a bronze printing-
colour which, although it dispenses with tallow, nevertheless gives quite prac-
tical results.
Having now particularly described and ascertained the nature of my inven-
tion and in what manner the same is to be performed I declare that what I
claim is:-
-1. The manufacture of bronze printing-colours by melting about 250 grammes
of a solution of copal or amber in linseed oil in the proportion of 1 gramme of
copal or amber to about 8 or 10 grammes of linseed oil, with about 200 grammes
of tallow and about 80 grammes of olein or paraffin oil or castor oil to a thin
fluid, adding to this fluid bronze powder until a pulpy consistency is attained
and, after the mixture thus obtained has been almost completely cooled, adding
thereto about 80 grammes of linseed-oil that has been thickened by boiling.
2. The manufacture of bronze printing colours by melting 1 gramme of
tallow with 04 to 05 gramme of linseed oil to form a thinly liquid mass, adding
bronze-powder to this mass until it has a pasty consistency, and then adding
very gradually 015 to 02 gramme of thickened linseed oil.
Dated this 17th day of November 1899.
W. LLOYD WISE,
46, Lincoln's Inn Fields, London, W.C., Chartered Patent Agent.