Year: 1898

page_text: J, SYDNEY PITT, of Sutton, in the County of Surrey, Gentleman, do hereby declare
the nature of this invention (which has been communicated to me from abroad by
The Pharmaceutisches Institut Ludwig Wilhelm Gans, of Frankfort-on-Main, in the
Empire of Germany, Manufacturing Chemists), to be as follows:-
The object of this invention is the production of all kinds of metal leaf, such as
gold leaf, silver leaf, and leaf of all metals of the platinum group, and also of any
desired mixtures or alloys.
For the production of leaf metal the so-called " ceramic lustrous preparations" and
the "ceramic lustrous preparations of the noble metals" are employed in the following
manner:
The solution of a lustrous preparation, for instance the resin acid compound of a
metallic oxide dissolved in ethereal oil, is laid upon a smooth sheet of glass, porcelain
or metal, not sensitive to heat or acids, and is burnt in, in the usual manner. After-
wards a solution of a lustrous metal preparation, as sold in the market, is laid on the
already burnt-in layer of lustre and is likewise burnt-in. With nonoxidisable
lustrous noble metals, such as gold or platinum, the burning is effected in an ordinary
fire; with the oxidisable metals, however, such as osmium, it is effected in the
reducing portion of the flame, or still better in a closed muffle, which is filled with a
reducing or indifferent gas, such as coal gas, hydrogen, or carbonic acid.
The skins of noble metal thus produced can now easily be detached by etching
the layer of lustre away by means of acids.
In this manner however one rarely succeeds in removing the skins whole as they
are easily torn to pieces.
The most perfect method of detaching the skins is by applying a coating of
collodion, gutta percha solution varnish or the like to the thin skin of noble metal
before etching the ground away.
Or an electrolytically deposited strengthened metal skin might be employed.
Now if the ground of the lustre be etched away, a leaf of noble metal of faultless
quality is produced, it having been perfectly protected by the collodion or cover froin
tearing, which otherwise would occur very easily.
In order to remove the collodion or other skin, different processes may be used,
such as dissolving or burning off.
For most purposes, however, it is best to leave on the cover, as the leaf of noble
metal will then be much more durable, so that it can be worked much more easily ;
this is a great advantage of the new method beside the absolutely uniform gauge of
the leaf which can never be obtained by the gold beating process.
To produce the lustre ground, the lustrous preparations of all metal oxides can be
used, which after being burnt in are soluble in acids.
The same effect, as with the lustres, is arrived at, if one employs fluxes easily
soluble in acids, viz., borosilicates, phosphates and the like, which are used in the
same way by laying them upon the sheet and burning them in.

page_text: For etching the lustrous layer, all mineral and all strong organic acids, such as
acetic acid, can be used.
It will easily be seen that any desired mixture or alloy, and consequently every
shade of colour, of one or more noble metals, can be produced by the corresponding
mixture of solutions of noble metal preparations.
Osmium leaf could not hitherto be produced by any process whatever, as osmium is
not fusible, and is not suitable for the gold beating method on account of its
infusibility and brittleness.
By this new method osmium leaf can be manufactured just as easily as any other
leaf.
By painting with solutions of noble metal preparations, any desired design or
pattern may be produced; after detaching the skin of metal together with the
collodion skin, they can be employed as decoration elements for gilding instead of
ordinary gold leaf and the like.
Improvements in the Manufacture of Metal Leaf.
I, SYDNEY PITT, of Sutton, in the County of Surrey, Gentleman, do hereby declare
the nature of this invention (which has been communicated to me from abroad by
The Pharmaceutisches Institut Ludwig Wilhelin Gans, of Frankfort-on-Main, in the
Empire of Germany, Manufacturing Chemists,) 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 a new process for the production of metal leaf, such as
gold and silver leaf, or that of the metals of the platinum group, or of alloys or
inixtures of the same.
In this process the so-called lustres or lustrous preparations of the metals are used,
which, now sold and used for the decoration of porcelain, glass etc., are organic
compounds of metals (resin acid compounds or sulphuretted resin compounds, or
products of the decomposition of metallic chlorides by heating them with lavender oil),
mixed in their application with an ethereal oil, such as lavender oil. Such lustres of
many metals are known. But there is a very remarkable difference between those,
which have for basis the so-called precious metals, i.e. gold, silver, and all the metals
of the platinum group,-and those, which have for basis the common non-precious
metals. The first ones, when applied upon porcelain, glass or metal, and then burned
in, leave behind a thin skin of metal, whilst the lustres of the non-precious metals,
when treated in the same manner, form a skin of metallic oxide.
The process is carried out as follows:-
A solution of a ceramic lustre (for example the resin acid compound of a metallic
oxide mixed with an ethereal oil) is spread upon a smooth surface of a material which
is acid resistant and capable of enduring unimpaired the temperature usually
employed to burn in the ceramic lustre employed, such as porcelain for example.
The ceramic lustre is then burned in upon the porcelain, or its substitute, in the
usual manner.
Fluxes easily soluble in acids, such as borosilicates or phosphates of
soda, etc. may be substituted for a ceramic lustre in this step of the process, if treated
in the same way by laying them on a plate and burning them in.
Upon this bed, as I shall call it, after it has been burned in, a ceramic lustrous
preparation of the desired noble metal is laid while in the condition in which it is
ordinarily applied in decorating porcelain etc., and is then burned in, in the usual

page_text: manner. This may be repeated again and again until the desired thickness is
attained, if one coat is thought insufficient for the intended purpose or it may be
thickened by electrolytic deposition of the metal.
Thus a skin, so to speak, of the desired noble metal is formed upon a bed of
ceramic lustre, which latter is attached to the porcelain or other plate upon which it
was originally burned in.
Though known in the art, it may not be amiss to mention, that while the lustres
of the non-oxidizable noble metals may be burned in without precaution against
oxidation, the lustres of the oxidizable metals, such as osmiuin, should be burned in'
in a reducing flame, or better still in a closed muffle in the presence of a reducing or
neutral gas, such as illuminating gas, hydrogen or carbonic acid.
The next step is to detach the skin of the noble metal. This is done by immersing
the plate in a solvent (principally inorganic and strong organic acids) of the bed (the
ceramic lustre) which is thus dissolved away, leaving the skin of the noble metal free
so that it can readily be peeled off from the plate.
But these skins of the noble metal, particularly if very thin, are easily torn. To
avoid such accidents it is advisable to brush over the skin of noble metal with some
form of tough varnish, such as collodion or a gutta percha solution after firing and
before endeavouring to detach the skin from the plate. This protecting coating can
O be dissolved away by any suitable solvent as soon as the metal skin is removed from
the plate; or it may be allowed to remain indefinitely to protect the metal skin until
its removal becomes desirable.
It is obvious that foil or leaf of any metal or alloy which may be used in the form
of a lustre to decorate glass or porcelain by burning in, may be made by this process
5 provided the precaution be taken to select as a bed (that is, the first application to
the plate) a lustre or flux which is soluble in a solvent which does not attack the metal
or alloy which it is desired to produce.
It is also obvious that metals may thus be produced in the foil or leaf form, which
by reason of their infusibility and lack of ductility and malleability are not adapted
O to the art of the gold beater, and cannot be rolled; while if deposited electrolytically
in metallic form from a cathode, these métals have so little cohesion that they cannot
be stripped off in the form of a foil or leaf and used on any other surface than upon
that where they are originally deposited.
Osmium is a case in point, which cannot be produced in thin sheet form by any
5 method heretofore known, for the reasons already given; but which can be as easily
produced by this method as foil or leaf of any other metal.
It is also obvious that by simply applying the lustres to the plate in the form of a
pattern or design, instead of covering the whole surface of the plate, the resultant
inetal will be in pattern or design instead of in a uniform leaf or sheet.
0 In order that the process may be better understood the following examples are
given.
EXAMPLE I. SHEET OR LEAF GOLD.
A flat piece of porcelain is painted with magnesium lustre and burned in in the
ordinary way. Then upon this magnesium lustre the lustrous gold ceramic prepara-
tion is laid, and the whole is again fired. Then upon this, if it is desired to toughen
the metal sheet to facilitate handling, a collodion varnish is applied. The plate with
its adherent material is then immersed in warm diluted sulphuric acid, when after
a few minutes the sheet gold skin can easily be removed. The collodion can there-
after be dissolved by a suitable solvent, or in many cases it can simply be burned off,
or it may be left to protect and strengthen the metal. Silver, iridium and rhodium
foil or leaf can be produced in the same way.
A flat piece of porcelain is painted with magnesium lustre and burned in in the
ordinary way. Then upon this magnesium lustre the lustrous gold ceramic prepara-
tion is laid, and the whole is again fired. Then upon this, if it is desired to toughen
the metal sheet to facilitate handling, a collodion varnish is applied. The plate with
its adherent material is then immersed in warm diluted sulphuric acid, when after
a few minutes the sheet gold skin can easily be removed. The collodion can there-
after be dissolved by a suitable solvent, or in many cases it can simply be burned off,
or it may be left to protect and strengthen the metal. Silver, iridium and rhodium
foil or leaf can be produced in the same way.

page_text: and burned in. Then upon this a lustrous osmium ceramic preparation is laid and
the whole is again fired. Then upon this a gutta percba solution may be applied, and
the whole dipped in dilute hydrochloric acid which dissolves the thorium-oxide-lustre
bed, when the osmium sheet or leaf may be removed and the gutta percha
dissolved off.
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 :-
1. The herein described process of manufacturing metal leaf, which consists first in
covering an acid and heat resisting plate with a ceramic lustre of an ordinary (non-
precious) metal and firing the same upon the plate to form a bed; second, in applying
thereto a ceramic lustre preparation of the desired metal and again firing; third,
subjecting the whole to the action of a solvent which will attack the bed but
not the desired metal, and finally peeling off the desired sheet or leaf from the
plate.
2. The herein described process of manufacturing metal leaf, which consists first
in covering an acid and heat resisting plate with a ceramic lustre of an ordinary
(non-precious) inetal and firing the same upon the plate to form a bed; second in
applying thereto a ceramic lustre preparation of the desired metal and again firing;
third, covering the same with a tough varnish, such as collodion; fourth, subjecting
the whole to the action of a solvent which will attack the bed but not the desired
metal and fifth, peeling off the desired metal sheet or leaf from the plate.
3. Metal leaf and the process of manufacturing the same substantially as
described.