An Improved Coating for the Interior of Metal Vessels
Year: 1896

page_text: Date of Application, 3rd June, 1896-Accepted, 25th July, 1896
COMPLETE SPECIFICATION.
An Improved Coating for the Interior of Metal Vessels
I, CARL FRIEDRICH HOHENBERG of Neue Post Strasse 250 Wittstock in the
Mark, in the German Empire, Confectioner, 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 :-
The object of this invention is to provide the inner walls of metal vessels
with a protective or insulating coating or lining, whereby the contents of the
vessel are protected from the contact and influence of metallic parts or surfaces,
or the vessel itself is secured against any dissolving or oxidising tendencies of
its contents. The improved coating or lining is more especially adapted for use
in connection with preserve tins or cans, for, as is well-known, food-and
particular canned meat-hitherto packed in sheet metal receptacles of this
description has been found, at least to some extent, however slight, to have been
injuriously affected by contact with the metal, so that continued use of such
preserved food could not fail, in the long run, to prove injurious to the health of
the consumers. Now this serious defect is entirely removed by the coat or lining
with which, according to this invention, preserve tins may henceforth be internally
covered, inasmuch as the same is apt to be affected neither by alkalies nor by acids.
The process by which the substance which is to form the protective lining is
obtained and applied is performed in the following manner :-
Permanent white (blank fix, or heavy spar, BaSO) in the form of powder is
at a normal temperature mixed with whites of eggs to the condition of a paste or
pulp. The inner walls of the vessels or receptacles to be protected, after having
been previously cleaned or washed with soda or the like, are coated with this paste
by means of a paint brush, or covered in any other convenient manner. The
coating is then allowed to dry by exposure to sufficiently heated air, when it will
become quite hard. After this a fresh layer of the paste is similarly applied over
the first and once more dried. When this has been done, the coating thus formed
is submitted to the action of either steam or, if preferred, boiling water, whereby
the albumen or white of egg will be caused to coagulate. The coating is then
again allowed to dry, once more impregnated with white of egg, once again
allowed to dry, and again treated with steam or boiling water.
If desired it may then be varnished over with a layer of collodium. This,
however, is not absolutely necessary.
The coating obtained in the manner above described is remarkable for its fastness
and durability as well as for its power of resistance both to mechanical and chemical
influences. It firmly adheres to the surface of the metal, so much so that it can
only be removed by the aid of a knife or similar tool. It is not liable to cracking
or scaling off, even should the vessel happen to be much indented by rough
handling, inasmuch as the improved coating substance is endowed with very
considerable elasticity. And it will furthermore successfully withstand the effects
of heat or hot fluids, so that vessels, thus protected, may also be employed in
boiling. The invention will be particularly valuable in the case of aluminium
vessels, the introduction of which into general use has hitherto been hindered by
the fact that the aluminium was apt to be affected or dissolved by certain ingredients
or substances occurring in the composition of food and beverages. This drawback
s entirely obviated by the improved lining or coating, with the result that aluminium

page_text: which, in other respects, presents so many advantages of great value, is rendered
unexceptionable as a material from which to manufacture food-containing vessels.
Having now particularly described and ascertained the nature of my said inven-
tion, and in what manner the same is to be performed, I declare that what I
claim is :-
A process for the preparation and application of a protective lining or coating
for metal vessels or receptacles of every description, such as preserve tins or cans,
pudding-moulds, travelling or campaigning (aluminium) flasks, or the like; the main
operations of which process are that the metal surfaces which have been previously
cleansed with soda or other suitable alkalies, are covered with either a single
coating, or a number of coatings, of a mixture of permanent white (or heavy spar)
and albumen (white of egg); each of which coats or layers (whatever their number)
is dried by exposure to heated air; then submitted to the action of boiling water
or steam; then again quickly dried; impregnated with white of egg; once more
submitted to the action of boiling water or steam, and lastly again dried.
Dated this Third day of June One thousand eight hundred and ninety-six.
MARKS & CLERK,
18, Southampton Buildings, London, W.C., and
13, Temple Street, Birmingham, Agents.
MARKS & CLERK,
18, Southampton Buildings, London, W.C., and
13, Temple Street, Birmingham, Agents.