A NEW OR IMPROVED PROCESS FOR PRODUCING A PROTECTING COATING OF RUST ON CAST IRON, WROUGHT IRON OR STEEL
Year: 1883

page_text: LETTERS PATENT to Lorentz Albert Groth. K.G.V. Civil Engineer and
"
Managing Director of The Universal Inventors and Patentees Financial
Company Limited 30 Finsbury Pavement London EC for an Invention of
A NEW OR IMPROVED PROCESS FOR PRODUCING A PROTECTING COATING OF
RUST ON CAST IRON, WROUGHT IRON OR STEEL communicated to him from
abroad by Erwin Nicolaus, a person resident at Lauchammer in the Kingdom
of Saxony German Empire
"
PROVISIONAL SPECIFICATION left by the said Lorentz Albert Groth at the
Office of the Commissioners of Patents on the 31st May 1883.
LORENTZ ALBERT GROTH K.G.V Civil Engineer and Managing Director of
The Universal Inventors and Patentees Financial Company Limited 30 Finsbury
Pavement London E.C. "A NEW OR IMPROVED PROCESS FOR PRODUCING
"
A PROTECTING COATING OF RUST ON CAST IRON, WROUGHT IRON OR STEEL
A communication to me from abroad by Erwin Nicolaus, a person resident at
Lauchammer, in the Kingdom of Saxony, German Empire,
The object of this process is to produce on objects of cast iron, wrought iron, or
steel a durable protecting covering of rust laid in regular coatings on the objects
and penetrating the surface thereof. The processes heretofore in use for protecting
iron partly against the action of the weather and partly to give thereto a coloured
coating exhibit faults which render it desirable to substitute for these processes one
of similar kind which enables a better result to be obtained and which is generally
applicable. Oil colour paint covers or veils too much the more or less valuable
decoration of the iron whilst galvanic coatings which avoid that evil do not adhere
well. The new or improved process forming the subject of the present invention
combines the covering power of oil paint with the fineness of galvanic covering and
possesses an extraordinary durability. The objects are thereby altered chemically
at their surfaces only and there is thus in reality no separate coating.
The process can be applied with equal safety to cast iron, wrought iron or steel.

page_text: The objects to be patinaed are first carefully ground and polished in order to
produce a clear metallic surface, to remove dirt and to prepare it to receive the
lustre or brilliancy required in some cases to complete the effect.
Then follows the most important minipulation, namely the annealing of the
objects Cast iron, especially such as is very thin, for artistic and architectural
purposes, by reason of its unequal thickness cannot be subjected to the process
unless annealed. The annealing of the cast objects is intended to make the
material homogeneous whereby the success of the succeeding operations is secured.
So called tempered cast articles must likewise be subjected to the annealing process.
Larger objects such as statues or monumental castings can be subjected to the
succeeding operations without further preparation, as their material possesses
sufficient homogeniety. When the articles are regularly annealed they are allowed
to cool slowly and are then placed in a pickle to remove the annealing scale. This
pickle may consist of a weak solution of sulphuric or muriatic acid in which the
article is immersed for a few minutes.
Then follows a mechanical working of the surface by scouring in order to remove
the scale completely
When the object is completely cleansed so that all uneven parts and annealing
scales are removed the peculiar patinaing process can be commenced.
This process
consists in so laying on a dilute inorganic acid (about one part acid to five parts of
water) that the surface is covered with a very thin coating of the liquid. After
covering over with this rust water the object is allowed to dry completely and it is
then brushed or rubbed with a brush or clean rags, after which the rusting
process is repeated in the same manner as before and the remainder of the rust
which is not fixed is removed after the subsequent drying by means of brushes and
rags. Finally the previously warmed cast article is painted over with Linseed Oil,
it is then dried in an oven or drying room and is then covered with colourless
lacquer (spiritus lac) which can be made highly brilliant at any required parts by
wax polishing.
Castings treated in this manner become of a beautiful durable black colour when
submitted to the action of heat in a stove
For browning wrought iron and steel the above described process gives better
results than the ordinary process and has the advantage of greater simplicity. In
treating wrought iron and steel the annealing process is dispensed with because
those materials already possess the homogeniety requisite for the patinaing
process

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Lorentz Albert Groth in the Great Seal Patent Office on the.
30th November 1883.
LORENTZ ALBERT GROTH, K.G.V. Civil Engineer and Managing Director of
the Universal Inventors and Patentees, Financial Company Limited, 30. Finsbury
Pavement, London, E.C. "A NEW OR IMPROVED PROCESS FOR PRODUCING
A PROTECTING COATING OF RUST ON CAST IRON, WROUGHT IRON,
A communication to me from abroad by Erwin Nicolaus a person resident at
Lauchammer in the Kingdom of Saxony, German Empire.
OR STEEL.'
"
The object of this process is to produce on objects of cast iron, wrought iron or
steel, a durable protecting covering of rust laid in regular coatings on the objects
and penetrating the surfaces thereof.
The processes heretofore in use for protecting iron partly against the action of
the weather and partly to give thereto a coloured coating, exhibit faults which
render it desirable to substitute for these processes one of a similar kind which
enables a better result to be obtained and which is generally applicable
Oil colour paint covers or veils too much the more or less valuable decoration of
the iron, whilst galvanic coatings which avoid that evil, do not adhere well
The new or improved process forming the subject of the present invention
combines the covering power of oil paint with the fineness of a galvanic covering
and possesses an extraordinary durability
The objects are thereby altered chemically at their surfaces only and there is
thus in reality no separate coating
The process can be applied with equal safety to cast iron, wrought iron or steel
The objects to be patinaed are first carefully ground and polished in order to
produce a clear metallic surface, to remove dirt and to prepare it to receive the
lustre or brilliancy required in some cases for the complete effect
Then follows the most important manipulation, namely, the annealing of the
objects
Cast iron, especially such as is very thin, for artistic and architectural purposes,
by reason of its unequal thickness cannot be subjected to the process unless
annealed
The annealing of the cast objects is intended to make the material homogeneous
whereby the success of the succeeding operations is secured
So-called tempered cast articles must likewise be subjected to the annealing
process.
Larger objects such as statues or monumental castings can be subjected to the
succeeding operations without further preparation, as their material possesses
sufficient homogeneity
When the articles are regularly annealed they are allowed to cool slowly, and are
then placed in a pickle to remove the annealing scale.
This pickle may consist of a weak solution of sulphuric or muriatic acid in which
the article is immersed for a few minutes
Then follows a mechanical working of the surface by scouring in order to remove
the scale completely
When the object is completely cleansed so that all uneven parts and annealing
scales are removed, the peculiar patinaing process can be commenced
This process consists in so laying on a dilute inorganic acid (about one part of
acid to five parts of water) that the surface is covered with a very thin coating of
the liquid

page_text: After covering over with this rust water, the object is allowed to dry completely
and it is then brushed or rubbed with clean rags, after which the rusting process is
repeated in the same manner as before and the remainder of the rust which is not
fixed is removed after the subsequent drying by means of brushes and rags
Finally the previously warmed cast article is painted over with Linseed oil, it is
then dried in an oven or drying room and is then covered with colourless lacquer
(spiritus lac) which can be made higbly brilliant at any required parts by wax
polishing
Castings treated in this manner become of a beautiful durable black colour when
submitted to the action of heat in a stove
For browning wrought iron and steel the above described process gives better
results than the ordinary process and has the advantage of greater simplicity
In treating wrought iron and steel the annealing process is dispensed with
because those materials already possess the homogeneity requisite for the patinaing
process
Having now described the nature of the said invention and the manner in which
the same is to be carried into effect, I would have it understood that what I
claim is:
First. The process for producing a protecting coating of rust on objects of cast iron
in the above described way, whereby smaller and weaker objects are
previously subjected to an annealing process in order to give the material
the homogeneity necessary for the process
Second. The use of the described process in its application to wrought iron or
steel, whereby the previous annealing process can be dispensed with,
substantially as above described
In witness whereof I the said Lorentz Albert Groth have hereunto set my
hand and seal this Thirtieth day of November in the year of our Lord one
thousand eight hundred and eighty three
LORENTZ ALBERT GROTH (L.S.)