Improvements in the Preparation and Production of Aluminium Plates for Printing Purposes.
Year: 1892

page_text: Date of Application, 12th Sept., 1892
Complete Specification Left. 10th June, 1893-Accepted, 15th July, 1893
PROVISIONAL SPECIFICATION.
Improvements in the Preparation and Production of Aluminium
Plates for Printing Purposes.
I, OTTO CARL STRECKER of Mainz, in the Empire of Germany, Doctor of
Philosophy do hereby declare the nature of my invention to be as follows:-
My invention has for its object to provide aluminium plates which can be used
with advantage for printing from, after the manner of lithographic printing.
I treat the plates of aluminium with any acid which will form, with aluminium, a
salt or salts insoluble in water and adhering firmly to the surface of the metal.
A lithographic transfer or lithographic drawing or design can be readily applied to
a plate so prepared. The treatment may be effected before the transfer or litho-
graphic drawing or design is applied or the transfer drawing or design may be
applied first and afterwards the said treatment be effected. As examples I give
the following for carrying out my invention but I do not limit myself thereto.
A sheet or plate of aluminium is suitably fixed, levelled, and smoothed. Then the
acid selected (say a solution of phosphoric acid of about 20 parts acid in 80 parts
water) is quickly applied with a sponge, or pad of linen, so that no bubbles are
visible. When the surface assumes a white opaque appearance the application of
the acid is discontinued and the plate is rinsed in water and a diluted solution say
of a basic sulphate of alumina is applied and allowed to dry and remains thereon
in a very thin coat or layer until immediately before the plate is to be used.
After the transfer or lithographic drawing or the like has been applied to this
plate the proceeding is like that hereinafter described as the "second facing."
If the plate is to be prepared after the transfer or the like is applied the following
may be the procedure.
The sheet, or plate of aluminium is made level smooth and clean and the transfer
or drawing or the like, is applied, and then the plate is gummed dried coated with
a solution of gum and then charged with transfer ink thinned with a medium such
as spirits of turpentine. In washing off ink with spirits of turpentine only a little
water is to be added and no asphaltum or quick drying fat or grease should be
used. The plate is again gummed dried and washed and then the treatment with
acid is proceeded with after the manner hereinbefore described and the plates may
be submitted to a "second facing" in doing which the acid solution should be
stronger.
Dated this 12th day of September 1892.
J. H. JOHNSON & Co.,
47, Lincoln's Inn Fields, London, W.C., Agents.
COMPLETE SPECIFICATION.
Improvements in the Preparation and Production of Aluminium
Plates for Printing Purposes.
1, OTTO CARL STRECKER of Mainz in the Empire of Germany Doctor of
Philosophy 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 :-
My invention has for its object to provide aluminium plates which can be used
with advantage for printing from after the manner of lithographic printing. I

page_text: treat the plates of aluminium with an acid which will form with aluminium a salt
or salts of aluminium constituting a "facing" insoluble in water and adhering
firmly to the surface of the aluminium. Suitable acids are ortho-phosphoric acid,
meta-phosphoric acid, pyro-phosphoric acid and bydrofluoric acid. The said facing
although insoluble in water attracts or retains water and therefore when moistened
with water will repel oily or greasy matter, and therefore will not take up the ink
used in inking a lithographic transfer or lithographic drawing, writing or design
applied to the plate in inks or chalks or the like such as are used in ordinary
lithography which can be effected in the same manner as in lithography. The
plates may be treated with acid as aforesaid before the transfer or lithographic
drawing writing or design is applied or the transfer drawing writing or design may
be applied before treatment with the acid. As examples I give the following for
carrying out my invention. A sheet or plate of aluminium suitably supported and
levelled is smoothed for instance with pumice stone or pumice stone powder and
water moved thereover with slight pressure. When the aluminium has assumed a
uniform dull and rough appearance polishing is effected by a softer grinding
material such as very fine pumice stone powder and water applied by soft felt.
Afterwards the plate is washed and dried and then the transfer drawing or the like
is applied and inked up and the treatment with the acid mixture is proceeded with
as hereinafter described. The acid mixture is composed as follows the parts being
by weight but I do not limit myself to the proportions given.
Take 10 parts of a solution of gum of about the consistence of ordinary oil and
3 parts of a saturated solution of gallic acid in water and 1 part of a 20 per cent.
solution of orthophosphoric acid.
Care must be taken to avoid the use of impure chemicals and only organic acids
such as the gallic acid should be used with the inorganic acid such as the phosphoric
acid.
To the sheet or plate of aluminium prepared as aforesaid and to which a
lithographic design writing or transfer has been applied the acid mixture can be
conveniently applied by means of a sponge or cotton pad saturated with the acid
mixture and rubbed quickly but gently over the surface so that no bubbles
are caused.
When the surface of the aluminium assumes a white opaque appearance the
application of the said acid mixture is discontinued and the plate is washed with a
solution of gum and then with water and if the plate is not to be immediately used
a solution of gum is allowed to dry on it.
The transfer or lithographic drawing or the like may be augmented in body by
magnesia or resin applied by means of a pad of cotton wool or the like rubbed over
the plate the excess being wiped off by a damp cloth.
The plate is then subjected to a second facing by treatment with the acid mixture
which for this I prefer to be stronger than for the first facing suitable proportions
being 4 parts of the saturated solution of gallic acid and 2 parts of the 20 per cent.
solution of ortho-phosphoric acid to 10 parts of the solution of gum.
If the plate of aluminium is treated with the acid mixture before the transfer or
the like is applied the said plate is treated so that its surface will take the transfer
ink or the like. This may be effected by a solution of alum or by a slight treatment
with organic acid, acetic acid for instance.
After the design has been applied to the prepared plate it may be submitted to a
"second facing in doing which the acid solution should be stronger as hereinbefore
mentioned. I do not however, limit myself to any particular number of applications
of the acid mixture.
In plates prepared according to my invention the drawing design writing or the
like is not raised above the surface as is the case with lithography but the bottom
part of the ink of the transfer or the like is below the surface formed by the
aluminium salt which enables results to be obtained in printing from plates prepared
according to my invention better than can be obtained by lithography.

page_text: 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. Aluminium plates for printing purposes prepared by treating the aluminium
by means of acid so as to form on it a salt of aluminium substantially as and for the
purpose herein before described.
2. The preparation of aluminium plates for printing purposes by first preparing
the surface as described then applying the transfer drawing or the like and
afterwards treating with acid so as to form on the aluminium a salt of aluminium
substantially as hereinbefore described.
3. The preparation of aluminium plates for printing purposes by first treating the
plate with acid so as to form a salt of aluminium thereon then applying the transfer
drawing or the like & afterwards treating with a stronger acid to form what I have
called the second facing all substantially as hereinbefore described.
Dated the 8th day of June 1802
J. H. JOHNSON & Co.,
47, Lincoln's Inn Fields, London, W.C., Agents.
J. H. JOHNSON & Co.,
47, Lincoln's Inn Fields, London, W.C., Agents.