IMPROVE- MENTS IN MEANS OF AND PROCESS FOR PRODUCING ORNAMENTAL OR OTHER DESIGNS UPON TIN PLATES
Year: 1882

page_text: PROVISIONAL SPECIFICATION left by Charles Johnson at the Office of
the Commissioners of Patents on the 10th May 1882.
CHARLES JOHNSON, of 54 Holborn Viaduct in the City of London "IMPROVE-
MENTS IN MEANS OF AND PROCESS FOR PRODUCING ORNAMENTAL OR OTHER
DESIGNS UPON TIN PLATES
"
My invention relates to what are ordinarily known as crystallized tin plates,
and it has for its objects a novel method and process for producing upon the surface
of such crystallized tin plates ornamental or other designs, the surface where such
designs are produced remaining uncrystallized whilst the remaining surface exhibits
the crystallization in the ordinary way. Such crystallized tin plates, which have
long been well known as Moireé Metallique, have heretofore been produced by
crystallizing the whole entire surface of the plates by well known processes in which
the tinned surface is first fused or partially fused, then cooled by the application of
water or other means, and treated with various acids, and finally in most cases
varnished with a clear or coloured Lacquer or varnish, whereby the ordinary effect
of a one-coloured or colourless crystallization over the whole surface of the plate is
obtained.
The object of my present invention is to produce tin plates partly crystallized but
having ornamental patterns, letters, or other devices, which are not so crystallized,
some portions of the surface of the plates being crystallized and the remaining
portions showing the tin surface either naturally bright, or illuminated in imitation
of gold, or in one or more colours.
In order to put my invention in operation I first prepare the tin plates for the
crystallization process by heating them in any convenient way until their tin surface
is almost fused, and then cooling them with water by a shower or plunge bath, and
I then polish their surface.
Upon the surface of the tin plates so prepared I print any desired ornamental or
other design or device, either by direct printing in a press of any ordinary kind, or
by transfer or offset, in one or more coloured or colourless varnishes, using preferaby
printing inks or varnish containing a sufficient proportion of gold size or other acid
resisting or quick-drying material or materials.

page_text: When the pattern or other design has thus been printed or produced upon the
tinned surface of the prepared plates, I immerse them in a bath of a suitable acid
of the requisite strength as ordinarily used, and the surface of the tin will become
crystallized upon those parts of the plate not protected by the printed design; whilst
the parts so stopped out will retain the ordinary bright tin surface.
The printing ink or varnish which forms the design may then be washed away
by any suitable solvent or detergent such as turpentine or paraffin, or it may be
allowed to remain.
When it is desired that the design should have the appearance of burnished gold,
it is printed or produced upon the prepared surface of the plates with ink composed
of the pigment well known as King's yellow combined with Lithographic or other
suitable varnish which is then dried in an oven or stove or by other convenient
means, and the plates are then treated with acid in the manner already described.
The ink composed as described and forming the design remains upon the plates
and gives to the polished portions of the latter underneath a perfect resemblance
to burnished gold, a result which it would be impossible to obtain if the whole
surface of the plates were crystallized before the design was produced upon them.
Before the removal of the printed or other design from the surface of the plates,
various colours may be applied to the crystallized surface of the plates in the
following manner.
I immerse the plates in a solution consisting of aniline dye of any desired
colour and strength in combination with citric acid and water in about equal
proportions.
By this means the crystallized portions only of the surface of the plates are stained,
and a great variety of shades of colour may thus be produced, whilst there is no
thickness of colour upon the surface which would be liable to cracking or removal
in bending or making up the plates for the purpose of manufacture into canisters,
boxes, or other articles for which they may be used when ornamented or decorated
in the way described.
Where it is desired to remove the printed or other design after it has dried upon
the plates, I place them after crystallization in a bath of cyanide of potassium in a
state of ebullition, by which the printing ink is removed and the design remains as
clear bright tin having a silvery appearance. The cyanide of potassium whilst
dissolving the dried printing ink does not develope the crystals upon the parts of
the plate which the ink has previously protected, and these parts consequently
remain bright and free from crystallization.