Year: 1887

page_text: Date of Application, 17th Dec., 1887
Specification Accepted, 10th Feb., 1888
We, ALBRECHT EDWARD BARTHEL of New York in the United States of America,
Engineer, at present residing at No. 34 Deich Strasse, Hamburg, Germany and JOHANN
CHRISTOPH JULIUS MÖLLER of No. 34 Deich Strasse, in the City of Hamburg in the
German Empire, Merchant, do hereby declare the nature of our said invention and in
what manner the same is to be performed to be particularly described and ascertained
in and by the following statement:-
Our invention relates to a process for providing metallic objects with a coating of
molten tin which possesses the advantage over the other metallic coatings or sheathings
produced on the electrolytic or galvanic system, such as nickel copper or brass, that it
does not oxidize so readily.
Our process can be employed with special advantage for tinning cast iron cooking
utensils, household and other implements of cast iron as the employment of poisonous
enamel is avoided and as much higher degree of polish attained.
Our process can also be employed for protecting architectural or other iron decora-
tions from rusting by the coating of tin or other metal without detriment to the
sharpness of the form as is the case with the customary oil or bronze paints.
In order to produce a perfectly even coating of tin on cast iron the same is first
provided with a thin coating of chemically pure iron regardless of the form of the
casting. This coating is produced in galvanic manner in a bath composed as follows:
600 grammes sulphate of iron Fe SO,, are dissolved in 5 litres water to which we add
a solution of about 2400 grammes carbonate of soda Na, CO₂, in 5 litres water. The
precipitate of ferro carbonate, Fe CO₂, resulting is dissolved in small quantities in so
much concentrated sulphuric acid until the fluid has a green color. The bath is now
rendered aqueous by adding about 20 litres water.
Blue litmus paper dipped in the bath must assume a deep claret color and red
litmus paper remain unchanged.
The objects to be provided with a coating of chemically pure iron are placed in the
bath opposite to the anode of cast or wrought iron or iron ore and both parts connected
to the corresponding poles of a dynamo machine, electric battery or other appropriate
source of electricity.

page_text: In a very short time the objects placed in the bath are covered with a coating of
iron, the thickness of which depends on the duration of the action of the bath or the
strength of electric current.
The so coated objects are then well rinsed in clear water, dried, then painted with
or immersed in a solution of ammonia in chloride of zinc or chloride of zinc alone and
then immersed in a vessel containing molten tin. The tin adheres with great tenacity
to the so prepared surface and the surplus of tin can be readily removed by a brush or
in other manner.
If the object to be tinned is of such size or so complicated in form that it cannot be
readily immersed in molten tin, it can be placed in a galvanic tin bath, which can be
readily made in any desired size, and be provided with a layer of tin of desired thick-
ness which after having been painted either with a solution of chloride of zinc or
ammonia in chloride of zinc can be heated to such a degree that the tin is equably
melted onto the said object or objects.
In like manner objects cast or made of lead or other readily melting metal which
would lose their form by melting when immersed in molten tin, are previous to tinning
provided with a coating of pure iron, and are then provided with a coating of tin in a
galvanic bath as mentioned above, without being subjected to heat for melting the
layer of tin deposited on the same
If objects of wrought or rolled iron or which do not require the afore described
treatment id. est. the production of a coating of chemically pure iron it will be
sufficient to carefully clean the same and paint them with a solution of ammonia in
chloride of zinc or only a concentrated solution of chloride of zinc.
This tinning process combines the advantage of simple manipulation and the great
durability of the coating with the cheapness of the manufacture which is partially
attained in the saving in tin.
Having now particularly described and ascertained the nature of our said invention
and in what manner the same is to be performed we declare that what we claim is :-
1. The process of tinning objects made from cast iron, lead and other inetals on to
which tin cannot be molton or adheres with difficulty consisting therein, that the said
objects are previously provided with a galvanic layer of chemically pure iron in a
bath of hydrate of ferro protoxide by employing an anode of iron, which said object
are then cleaned, painted with a chloride of zinc solution or a solution of ammonia in
chloride of zinc and immersed in a bath of molten tin, or coating the same with tin in
a galvanic bath alone or heating the same so as to cause the deposited tin to melt and
firmly combine with the iron, substantially as and for the purpose set forth.
2. The process of tinning objects of wrought or rolled iron or steel consisting in
previously cleaning the same then painting them with a solution of ammonia in chloride
of zinc or a solution of chloride of zinc alone and then immersing the same in a bath
of molten tin, substantially as and for the purpose set forth.
Dated this 17th day of Dagambar 1887