Improvements in Coating Aluminium and Aluminium Alloys.
Year: 1893

page_text: Date of Application, 10th Jan., 1893-Accepted. 8th July, 1893
COMPLETE SPECIFICATION.
Improvements in Coating Aluminium and Aluminium Alloys.
We, GEORG WEGNER of Oppelner Strasse, Berlin, Germany, Goldsmith, and
PAUL GÜHRS of 67 Berliner Strasse, Rixdorf, near Berlin, Locksmith, 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 relates to the coating of aluminium or aluminium alloys and it has
for its object to do so by an improved process.
The coating, which has a colour and possesses a high gloss, protects the
aluminium from the action of damp &c.
In carrying out the process under one method, with pure aluminium or an alloy
containing at least 80% of aluminium, we first brush the metal over with a solution
composed of the following ingredients mixed together in or about the proportions
named, for 1 litre of the mixture-acetous verdigris 30 gramms, oxide of iron
30 gramms, sulphur 30 gramms and sal-ammoniac 10 gramnis, and then heat it to
a high temperature, thereafter the metal is again brushed over with the solution
and then re-heated. The metal is now brushed with a sharp brush and then painted
over with a mixture formed of 10 gramms sulphur dissolved in 100 gramnis
turpentine and then again fired or heated. The metal is finally dipped into a hot
bath of pure linseed oil and kept there until the oil has entirely evaporated.
By this process the metal is covered with a coloured coating which adheres so
strongly that it will not peel off or crack even though the metal itself is bent or
broken.
A gloss or glaze is or may be formed on the coating by brushing it over with a
solution of bees-wax dissolved in turpentine. The effect of the brushing is to
slightly heat up the metal whereupon the wax forces itself into the coating and
imparts to it a certain degree of flexibility. The bees wax also promotes the
adhesion of the coating and it serves to protect the metal from the action of the
atmosphere.
If it is desired to produce a light or dark shaded coating on the metal the process
is as follows:-
The metal is first dipped in a bath consisting of vinegar (1 litre) ammonium
chloride (200 gr.) and chloride of iron (100 gr.) it is then heated and thereafter
cooled: it is now painted over with a pulpy mass formed by mixing together red
sulphur (30 parts) and bloodstone (20 parts) in a finely pulverised state with liquid
sulphide of ammonium (10 parts) and subsequently again heated. The red-
sulphur here referred to is the natural product dug up along with ordinary yellow-
sulphur.
After this treatment the metal is painted over with a pulpy mixture formed of
turpentine (100 gramms) and bloodstone (10 gr.) and may be thereafter operated
on, as in the first, above described, process, with the wax brush until the surface
appears coloured and bright. The shading or tinting of the various colours, such
as for example, giving light and dark shades, can be done by using smaller or
larger quantities of bloodstone and sulphide of ammonium.
It is to be understood that we do not confine ourselves to the precise quantities
specified for the several ingredients in the mixtures.
Having now particularly described and ascertained the nature of our said inven-
tion, and in what manner the same is to be performed, we declare that what we
claim is :-
1. A process of coating aluminium or its alloys consisting in first painting the

page_text: metal with a solution of acetous verdigris, oxide of iron, sulphur and sal-ammoniac
and then subjecting it to heat, thereafter again painting and heating the metal;
subsequently brushing it, and then painting it over with sulphur dissolved in
turpentine and firing it; finally steeping it in a bath of linseed oil; the coating
may or may not be brushed over with bees-wax, substantially as herein before
described.
2. A process of coating aluminium and its alloys, consisting in first dipping the
metal in a solution of chloride of iron, ammonium chloride, and vinegar, then
heating and cooling it; then coating it with a mixture of red sulphur, bloodstone,
and sulphide of ammonium, then again heating and cooling it, thereafter painting it
over with bloodstone and turpentine and finally brushing or not with a wax brush
to produce a glaze, substantially as hereinbefore set forth.
Dated this 9th day of January 1893.
H. D. FITZPATRICK,
70, Wellington Street, Glasgow, Agent.