Improvements relating to Rust Preventive Paints.
Year: 1893

page_text: Date of Application, 27th Nov, 1893
Complete Specification Left, 3rd Aug. 1894-Accepted, 17th Nov.. 1.894
PROVISIONAL SPECIFICATION.
Improvements relating to Rust Preventive Paints.
I, Dr. AUGUST BUECHER, Chemist, of Heidelberg, in the German Empire, do
hereby declare the nature of this invention to be as follows:-
This invention has for its object, to prevent iron and steel temporarily or
permanently from rust. For the manufacture of a paint or coating specially
suitable as a protection from rust, I employ a mixture of very finely divided zinc
and calcium carbonate, with the addition of polishing substances such as washed
tripoli, colothar, vegetable charcoal. The substances mentioned above are well
dried, sieved, and bolted. This mixture of powders is then mixed with an alcoholic
solution of saponate having a specific gravity of 0.925. For producing this
saponate solution, I employ two parts of a saponate prepared from olive oil, potash
solution, alcohol and water, and one part of a saponate prepared from olive oil, pork
grease, lead oxide, potassium carbonate and water. Pure benzene is added to the
mixture of the two saponates, as long as the liquid remains clear. The mixture of
powders and the liquid are stored separately, because the joint keeping of the
components in a closed vessel must be avoided on account of a strong mutual reaction
which would take place.
'
Shortly before use, the components are intimately mixed in a dish by means of
a paint brush which is subsequently to be used for applying the paint. The relative
weights of the mixture of powders and of the alcoholic saponate solution to be used
are as 1 to 2. This mixture is allowed to stand in a cool locality from 10 to 15
minutes, after which time the paint possesses the required consistency. The iron
utensils to be coated with the paint must have been carefully cleaned from fat and
other impurities. For objects which are kept under cover, a single coating is
generally sufficient.. but objects which are to be exposed to the weather, should
be coated twice.
The paint is applied in such a manner, that the metallic surface will no longer
be visible through the same (that is the coating should not be translucent). The
substance dries during its application, and in a few days the atmospheric air
renders it so solid, that neither snow nor continued rain will be able to wash the
paint away from the metallic surface.
As soon as the object painted with this paste is to be used, the coating is brushed
with a dry brush, which only requires a few moments.
The new compound will not smudge the metal surface, as is the case with some
other rust-preventive compositions.
The polish and brilliancy of the metallic surfaces thus treated are not destroyed,
even by several years of use, and may even increase, because during the removal
of the paste its polishing ingredients will come into action.
Iron and steel remain free from rust, as long as their surfaces are covered with
the new composition. Consequently, the new rust-preventive compound is specially
suitable for preserving arms, surgical instruments, stationary machines and their
reserve parts, and hardware kept in stores.
For permanently protecting iron structures from rust, which must be done in
the case of bridges, girders, etc., the manufacture is modified in the following
manner. Instead of mixing the pulverized mixture with the above described
saponate solution, it is mixed with an alkaline glutin solution, and the tripoli
powder which acts as a polishing ingredient, is omitted.
To a boiling aqueous glutiu solution a hot concentrated mixture of sodium

page_text: borate and potassium carbonate is gradually added while constantly shaking, and
the mixture is kept slightly boiling for about half an hour. Subsequently the
liquid is allowed to stand in a well-closed receptacle in a cool place for about
14 days, and then filtered over charcoal. In this manner a clear, non-gelatinising
and durable liquid of 10350 specific gravity is obtained.
The method of applying this paint is the same as that described above, except
that the ratio between the weight of the dry substances to be used to the alkaline
glutin-solution is as 2 to 1. This paint dries rapidly and hardens in a few hours,
unlike the protective compound produced with saponate solution, to such an extent,
that it can scarcely be removed by mechanical means. This property renders the
protective paint highly suitable as a ground coating for oil paint. By applying
over this ground coating a layer of oil paint, the protection against rust becomes
waterproof and therefore permanent.
The oil paint may be applied immediately; a single application or layer of the
new mass as a ground coating, and a single coat of oil paint is sufficient.
Dated this 27th day of November 1893.
FAIRFAX & WETTER,
Agents for the Applicant.
COMPLETE SPECIFICATION.
Improvements relating to Rust Preventive Paints.
I, Dr. AUGUST BUECHER, Chemist, of Heidelberg, 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 has for its object, to prevent iron and steel temporarily or
permanently from rusting. For the manufacture of a paint or coating specially
suitable as a protection from rust, I employ a mixture of very finely divided zinc
and calcium carbonate preferably about two parts of zinc to one part of chalk to
which are added about one half per cent. of polishing substances, such as washed
tripoli, colcothar, vegetable charcoal. The substances mentioned above are well
dried, sieved, and bolted. This mixture of powders is then mixed with an alcoholic
solution of saponate having a specific gravity of 0.925. For producing this
saponate solution, I employ two parts of a saponate prepared from olive oil, potash
solution, alcohol and water and having a specific gravity of about 0.9193, and one
part of a saponate prepared from olive oil, pork grease, lead oxide, potassium
carbonate and water and having a specific gravity of about 0.9385. Pure benzene
is added to the mixture of the two saponates, as long as the liquid remains clear.
The mixture of powders and the liquid are stored separately, because the joint
keeping of the components in a closed vessel must be avoided on account of a
strong mutual reaction which would take place. Instead of calcium carbonate,
magnesium carbonate or analogous compounds may be used, and the polishing
substances may be varied in quantity or omitted.
The saponate solution of 0-9193 spec. gravity mentioned above, may be produced
by heating 10 parts of olive oil with 5 parts of potassium carbonate, 7 parts of
alcohol and 10 parts of water, until complete saponification has set in, subsequently
adding 23 parts of alcohol and 10 parts of water, and filtering.
The saponate solution of 0.9385 spec. gr. mentioned above may be obtained as
follows:
15 parts of olive oil are ground together with 5 parts of pork grease
(mixture A); 10 parts of litharge are ground together with 3 parts of water to
form a paste, then added to mixture A, and the whole is heated (boiled) with a
moderate fire until a viscous mass has been produced. Of this tough or viscous
mass 160 parts are liquefied over a water bath and ground with 30 parts of pure

page_text: potassium carbonate to a uniform mass. This mass is repeatedly extracted with
strong alcohol, and finally the alcoholic extracts are filtered.
Shortly before use, the components are intimately mixed in a dish by means of
a paint brush which is subsequently to be used for applying the paint. The
relative weights of the mixture of powders and of the alcoholic saponate solution
to be used are as 1 to 2. This mixture is allowed to stand in a cool locality from
10 to 15 minutes, after which time the paint possesses the required consistency.
Iron utensils to be coated with the paint must have been carefully cleaned from fat
and other impurities. For objects which are kept under cover, a single coating is
generally sufficient, but objects which are to be exposed to the weather, should
be coated twice.
The paint is applied in such a manner, that the metallic surface will no longer
be visible through the same (that is, the coating should not be translucent). The
substance dries during its application, and in a few days the atmospheric air renders
it so solid, that neither snow nor continued rain will be able to wash the paint away
from the metallic surface.
As soon as the object painted with this paste is to be used, the coating is brushed
with a dry brush, which only requires a few moments.
The new compound will not smudge the metal surface as is the case with some
other rust-preventive compositions.
The polish and brilliancy of the metallic surfaces thus treated are not destroyed,
even by several years of use, and may even increase, because during the removal
of the paste its polishing ingredients will come into action.
Iron and steel remain free from rust, as long as their surfaces are covered with
the new composition. Consequently, the new rust-preventive compound is specially
suitable for preserving arms, surgical instruments, stationary machines and their
reserve parts, and hardware kept in stores.
For permanently protecting iron structures from rust, which must be done in the
case of bridges, girders, etc., the manufacture is modified in the following manner.
Instead of mixing the pulverized mixture with the above described saponate
solution, it is mixed with an alkaline glutin solution, and the tripoli powder which
acts as a polishing ingredient, is omitted.
An aqueous glutin solution is prepared by dissolving (80 grammes of) glue in
(liter of) water over a water bath, and introducing this solution into (1 liters
of) boiling water. This glutin solution is maintained at a temperature varying
from 80 to 90° C. for about 30 or 35 minutes. In the meantime a concentrated
mixture of sodium borate and potassium carbonate is prepared by dissolving
(60 grammes of) borax and (4 grammes of) potassium carbonate in (100 cubic
centimeters of) water, and the solution kept boiling for about 20 minutes. There-
upon the said saline solution is gradually introduced into the glutin solution, while
constantly shaking, and the mixture is kept slightly boiling for about 10 minutes.
Subsequently the liquid is allowed to stand in a well-closed receptacle in a cool
place for about 14 days, and then filtered over charcoal. In this manner a clear,
not gelatinising and durable liquid of yellowish colour and 10350 specific gravity
is obtained.
The method of applying this paint is the same as described above, except that
the ratio between the weight of the dry substances to be used to the alkaline
glutin solution is as 2 to 1. This paint dries rapidly and hardens in a few hours,
unlike the protective compound produced with saponate solution, to such an extent,
that it can scarcely be removed by mechanical means. This property renders the
protective paint highly suitable as a ground coating for oil paint. By applying
over this ground coating a layer of oil paint, the protection against rust becomes
waterproof and therefore permanent.
The oil paint may be applied immediately, a single application or layer of the
new mass as a ground coating, and a single coat of oil paint is sufficient.
The advantages of the new protective paint in comparison with red-lead paints
are evident. The paint does not scale off, and the injurious after-effects of metallic

page_text: sulphides and sulphates frequently contained in ordinary paints, are avoided. As
a single coating is sufficient, and all operations may be carried out in rapid
succession, the present invention will also save much time.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is ;-
1. The manufacture of a rust-preventive paint, by preparing a mixture of
finely divided metallic zinc, calcium carbonate (or similar compounds) and (in
certain cases) polishing substances such as tripoli, colcothar, vegetable charcoal,
and adding an alcoholic saponate solution or an alkaline glutin solution shortly
before use, substantially as described.
2. A rust-preventive paint composed of finely divided metallic zinc, calcium
carbonate, (or similar compounds) an alcoholic saponate solution or an alkaline
glutin solution and (in certain cases) a suitable polishing substance, substantially
as described.
Dated this 3rd day of August 1894.
FAIRFAX & WETTER,
433, Strand, London, Agents.