A Process for Producing Printing Surfaces upon Zinc and Copper Plates, Applicable to the Production of Copper and Zinc Printing Rollers.
Year: 1890

page_text: Date of Application, 25th Feb., 1890-Accepted, 31st May, 1890
COMPLETE SPECIFICATION.
A Process for Producing Printing Surfaces upon Zinc and Copper
Plates, Applicable to the Production of Copper and Zinc Printing
Rollers.
I, WILLIAM LOFTUS HARE 7 Bride Court Fleet Street London, Photo-engraver
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:
I take a plate of ordinary polished zinc & stain it black by means of a solution of
salts of antimony in water after which I transfer upon it the key drawing previously
made, by the usual method of lithographic transfer. I then pass the plate in acid and
deposit upon it a fine powder of resin which melts & becomes adherant to the plate
upon the application of heat from any suitable apparatus say a stove or a number of
gas jets. Having now the grain upon the plate I paint with a brush such parts of the
picture as I desire to be solid colour, being guided in this operation by the key
transfer which remains upon the plate during the whole process. I then subject the
plate to a slight etching in nitric acid and water which bath reveals to the oye a fine
grain previously almost imperceptible. After having dried the plate I proceed in the
same manner as before covering such parts of the picture as I wish to be solid. The
bath just described leaves the plate etched all over except in such parts as are
protected with the varnish which is used by means of the brush as before mentioned.
This varnish may be composed of anything that will resist acid & flow conveniently
when applied to the zine plate.
After each covering I etch the plate, the result of which is that the unprotected
parts are lightened in colour. The number of etchings depends upon the number of
tones there are in the colour which is being worked upon.
When the stages are complete I wash the plate in the ordinary manner with
turpentine & potash. All other plates are treated in precisely the same way. In
case there are colour plates in which I desire absolute white I cover all the parts to be
retained with the brush & varnish and etch away the remainder entirely.
The manner in which I make the zinc rollers is as follows: after treating the plate
in the way described above I bend it upon a roller made of cast iron or any suitable
metal and I fix it down with screws; it is then ready for printing wall papers or fabrics
by relief printing.
With regard to the copper rollers, the method I employ is a little different. [
treat the copper plate similarly to the zinc plates as far as the depositing of the grain
upon it. Then I paint out such parts with the varnish as I desire to be white in the
printed impression; following which I etch in perchloride of iron or any suitable
etching fluid. I then paint out such parts as are nearly white & proceed in this way
until eventually I come to those parts which are to be solid black-to which parts I
give as much etching as possible. I then bend the copper plate upon to a roller of cast
iron or any suitable metal & I fix it on with screws, or in any way which I find most
desirable.
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 1
claim is
(1.) That the process admits of producing by letterpress printing, chromographic
work hitherto effected by means of lithography only.
(2.) That the results obtained are even superior to lithography especially so when
it is considered that on an average ths the number of colours employed in litho-
graphy are required for this process. The reason of this is that upon one plate I can

page_text: obtain a graduation from solid black to an almost imperceptible black. This obviates
the necessity of employing two different shades of any special colour as is always the
case in high class chromolithography.
(3.) The process has also the advantage of economy in its printing stage & I claim
especially that in cases where many thousand copies of one particular illustration are
required the cost is very sensibly reduced.
(4.) 1 also claim that there is no process more suitable for the production in
facsimile of water colour drawings. The results I have obtained in this direction fully
justify this last statement.
(5.) I also claim that the process, so far as it refers to the production of rollers has
great advantages both in saving of time & labour & also to the excellence of result,
for hitherto all copper rollers are engraved by hand being a most expensive and
lengthy process.
Dated this Twenty fourth day of February 1890.
WILLIAM LOFTUS HARE,
7, Bride Court, London, E.C.