Improvements in the Method of Producing Thin Films of Metal and Manufacturing Metal Surfaced Paper therewith.
Year: 1893

page_text: Date of Application, 7th Feb., 1893-Accepted, 11th Mar., 1893
COMPLETE SPECIFICATION.
Improvements in the Method of Producing Thin Films of Metal and
Manufacturing Metal Surfaced Paper therewith.
I CARL ENDRUIVEIT of Lindowerstrasse 21; Berlin N., in the Empire of
Germany Manufacturer do hereby declare the nature of this invention and in
what manner the same is to be performed to be particularly described and ascer-
tained in and by the following statement :-
In previous methods or attempts to produce metallic paper, that is paper with
a metallic surface by means of a galvanic precipitate it has been found practically
impossible to so protect the cathode plate, upon which the thin layer of metal is to
be deposited, that the precipitated metal shall be equal throughout and capable of
being lifted off easily from the cathode plate when the paper backing has been
pasted on to the precipitated layer of metal.
The previous coating or protecting of the cathode-plate has been effected by
providing the plate with a fine covering layer of fat or of lac; but as it is
practically impossible to lay on this coating equally thick in all places, the
deposited metal coating will also be irregular and if for instance, the slightest
point even of the dimensions of a needle point is left unprotected on the cathode
plate, it is hardly possible and only by damaging the nietal skin, to lift the latter
from the plate; for these reasons looking to the time necessary for careful operation
and the great waste of spoilt sheets the cost of manufacture of such sheet has been
about one shilling a piece, a price practically prohibitive.
Furthermore it has not yet been found possible to paste the paper backing to
the skin of metal so as to produce an absolutely solid and lasting connection between
the metal and the paper, for in most cases it is possible to pull the paper from the
metal after the paste is dry.
These previously described disadvantages are obviated by the improved process
hereinafter described by which the cost of manufacture is reduced to about
three half pence per sheet.
In the previous method it was necessary to polish and re-coat the cathode plate
after making each sheet, but by the present process an unlimited number of sheets
may be taken off without interruption.
The improved process is as follows:
or
A well polished yellow-brass or nickeled sheet of metal is wetted by means of a
paint-brush or sponge with a solution of higher alkaline sulphide or hydro-
sulphide for instance: 5 parts by weight of potassium, tri-sulphide (HS)
hydro-sulphide (KSHS) to 100 parts of water, this solution further containing
1% of spirit. By such means an effective protecting coating is produced, though
not observable to the naked eye. Such chemical means avoids the mechanical
covering of the plate previously necessary.
Spirit is added to the solution to remove the greasy particles which may possibly
be present, so that the solution of sulphide may be capable of exercising its effect
over the whole surface.
After this treatment the plate is washed with clean water and immediately
immersed in a suitable solution of a copper or nickel salt and exposed to the effect
of an electric current. The copper-bath consists of one part of sulphate of copper
and 5 parts of water and must be kept as neutral as possible similarly the usual
nickel bath when that is employed, all free sulphuric acid being taken of by putting
in a carbonate.
Nickel plates or nickeled metal-plates may be put directly in the acid copper
bath.
In these solutions the plates are to be kept only short time, after which they are

page_text: placed in the usual acid copper-bath and subjected to the further influence of the
electric current, until the galvanic deposit produced has attained the desired
thickness. After this is done the cathode-plate is taken out and transfered to a
sulphate of zinc bath for a very short time where it is exposed to repeated passages
of the electric current to produce a deposit of zinc which with the paste employed
will give a solid and intimate junction between paper and metal.
The plate is removed from this bath and the zinc is lightly treated with a
solution of ammonium hydrosulphate NH,H,S mercaptan or a similar com-
pound HS(C,H.),S ;-sulphide of allyle (C,HS; then the sheet of paper coated
with starch paste to which is added one fourth of animal glue is pasted on the metal
skin. Instead of treating the zinc deposit with the above named solutions the latter
may be mixed shortly before use with the paste.
For receiving copper-deposits it may be mentioned that nickeled yellow-brass
plates are preferably used because the copper deposit can be removed very easily,
and the employment of the second acid copper bath is unnecessary because the
deposit produced in the first bath is sufficient.
These copper deposited skins pasted upon the paper are when dry, rubbed over
with a mixture of gold or silver-cyanate with carbonate of potash.in order to
produce a real gold or silver paper, whilst the nickel paper remains as it is.
The metallic paper obtained in the manner described is of uniform and brilliant
surface and as to durability practically indestructible.
Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to bé performed I declare that what I
claim is.
1. The improved method for producing on plates detachable metal films consisting
in treating a metal plate with a solution of the higher alkaline sulphides or hydro-
sulphides with a small proportion of a grease solvent such as spirit to produce a
uniform resistent coating on the plate previous to galvanic or other deposition of
the film of metal thereon.
2. The method of producing on plates detachable metal films consisting in treating
the metal plate with the solution described in Claim 1 and immersing the plate first
in a neutral solution of sulphate of copper, 1 part to 5 parts of water and afterwards
in an acid copper bath for galvanic plating.
3. For the manufacture of paper with metallic surface, the method consisting in
producing a thin metal film upon a suitable plate, depositing zinc thereon, and subse-
quently treating the same with a solution of hydrosulphate of ammonia (NH,H,S);
mercaptan or similar compound HS(C,H.),S or allylesulphide (CH),S previous
to pasting the paper thereon or causing the paper to adhere by paste in which the
said substances are mixed.
.
4. The finishing of the metallic surface of the paper so produced by means of
cyanate of gold or silver and an alkaline carbonate to produce gold or silver paper.
Dated this 7th day of February 1893.
R. HADDAN,,
Herbert Haddan & Co.,
18, Buckingham Street, Strand, London, Agent for Applicant.