LITHOGRAPHIC TRANSFER INKS
Various Forms--Distinguishing Features--Formulæ--Writing
Transfer Ink--Stone-to-stone Transfer Ink--Copperplate
Transfer Ink--A Modification.
Given a perfectly clean and smooth polished stone as described in the
previous chapter, the next important point is the composition of the
fatty matter wherewith a design or drawing is applied.
As already stated, the active principle in any suitable transfer medium
of this character is invariably the same, no matter what form its
composition takes. For applying with pen or brush it must possess
soluble properties, and of necessity be reduced to a liquid form. Such
soluble properties, however, must not interfere with its fatty
properties, these latter being essential features.
In crayon or _chalk_ drawing the composition must be employed in a
concrete form, as a crayon, the hardness and texture of which will be
controlled (1) by the character of the work to be carried out; (2) by
the character of surface to be operated upon.
Transfers from other printing surfaces can only be made when the
composition used is in the form of a pigment, and reduced to a
convenient working consistency.
These, then, comprise the varieties of transfer mediums which are likely
to be required in most phases of commercial lithography. Others are, of
course, employed for specific purposes and under peculiar conditions;
but these, again, are more or less modifications of existing formulæ,
prepared to meet particular requirements.
The ink used for transferring impressions from one printing surface to
another, _e.g._, the re-transferring of work from stone to stone, may
with a very slight alteration serve for type to stone transfer; but a
considerable departure must be effected to produce a satisfactory
photo-litho transfer ink, while a composition of a peculiarly
distinctive character will be requisite for the successful production of
transfers from copperplate engravings, as well as for a transfer ink for
writing and drawing on stone or transfer paper. This writing transfer
ink must be soluble in water, yet without becoming slimy; otherwise it
will not work freely with the pen or brush. It must also dry quickly,
and without any tendency to smear.
A plate transfer ink must neither melt nor drag when applied to the hot
plate. It must, of course, soften sufficiently to fill in the lines of
the engraving, and should so harden as it cools that it cannot easily be
dragged away during the cleaning and polishing operations. See Chap. IV.
page 19.
Each and all of the above inks must be excessively greasy and
penetrative, but without having the slightest tendency to spread
superficially. The ingredients and methods of preparation specified in
the succeeding paragraphs are not given as standard formulæ, but in
corroboration of statements made, and as practical illustrations of the
character and purpose of transfer inks and compositions generally.
_Transfer ink._--Writing transfer ink, for writing or drawing on stone
or transfer paper, may consist of equal quantities of:--
Castile soap,
Wax,
Tallow,
Shellac,
with the addition of carbon black or black printing ink as a colouring
matter. Another reliable formula is:--
Soap 4 parts
Tallow 3 parts
Wax 6 parts
Shellac 4 parts
Carbon black 1 parts
Whichever formula is adopted the method of preparation is the same
combination.
Free the soap from all moisture by drying, and thus facilitate its
combining with the other ingredients.
Melt the tallow and wax over a hot fire until they are thoroughly well
mixed. Add the dried soap a little at a time, so that it may become
thoroughly incorporated with the wax and tallow. Bring the mixture to
boiling-point, then remove it from the fire or stove and ignite the
fumes which will then be rising freely. Continue the burning process for
about fifteen minutes, then extinguish the flames by replacing the lid
of the pan. The shellac and black may be added while the composition is
cooling.
_Stone-to-stone re-transfer ink._--The ingredients of this ink consist
of:--
4 oz. Transfer ink.
4 oz. Litho black ink.
4 oz. Medium varnish.
1 oz. Canada balsam.
Melt the transfer ink over a slow fire and add the other ingredients
separately.
Canada balsam will not only add to the effectiveness of this ink, but it
will also improve its working qualities.
_Copperplate transfer ink._--Ingredients consist of:--
1 oz. Tallow.
3 oz. Bee's wax.
4 oz. Shellac.
2 oz. Soap.
4 oz. Bitumen.
1 oz. Canada balsam.
1 oz. Carbon black.
The method in this case differs somewhat from the preceding. First melt
the bitumen and then add the wax and soap in small pieces as before.
Burn this for fifteen minutes, and add the shellac, balsam, and black,
boiling the whole gently for forty minutes. Mould into squares or
sticks, and for convenience in handling cover these with tinfoil.
Should an extra powerful ink be required for shading or stippling films,
the stone-to-stone re-transfer ink can be reduced to a working
consistency with castor oil instead of varnish, and thus rendered
suitable for this purpose.