VARIOUS TYPE MATRICES FOR RUBBER STAMPS AND TYPES.
Matrices for stamp moulds can be made by several of the methods used by
stereotypers. Thus an electrotype could be taken directly from the face
of the type. There would be little or no utility in doing this where
the simpler processes are available.
PAPIER MACHÉ MATRICES.
The stereotyper for daily newspaper work uses very generally the
papier maché or “flong” process of reproducing the page. This is also
available for rubber stamp making.
The first requirement is paste. This is made by softening twelve parts
of whiting in forty parts of water, letting it soak for an hour or
more. Nine parts of wheat flour are added. This is best mixed with a
little water before adding to the main mixture. It is then brought to
the boil and seven parts of glue softened by soaking in twenty-one
parts of water, are added. For each gallon of such mixture, one ounce
of white crystallized carbolic acid is added if it is to be kept for a
long time.
The “flong” is made by pasting together, one on top of the other, a
sheet of fine hard tissue paper, three sheets of blotting paper (about
23 pounds to the ream), and a heavy sheet of manilla paper. The pasting
must be smooth and each layer must be pressed and rubbed down, but
not too hard. It is very important to secure perfect smoothness and
regularity, and entire absence of air bubbles.
Every printing office where the process is used has its own
traditions as to the preparation of flong. As a great deal depends on
manipulation, it would be well to endeavor to inspect its practical use
in a newspaper printing office before making it. Ready prepared flong
can also be procured.
The form of type must be very clean and there must be no paste on
the tissue paper face of the flong. The type are lightly oiled, some
powdered talc is dusted over the damp tissue paper face of the flong,
and the mass is laid face downward on the type. With a stiff haired
brush the paper is now beaten down against the type. Great care must be
taken to beat vertically; a slight side action will ruin the resulting
matrix. If the brown paper will not stand the beating, a cloth may be
spread over it.
The progress of the work can be watched by raising up a corner from
time to time. When sufficiently deep the last touch is given by the
printer’s planer. This is a block of hard wood. It is placed upon the
back of the flong and is hammered down. The operation is repeated until
the entire area has been treated. For much rubber stamp work the area
would be so restricted that shifting would be unnecessary.
The work is then put into a heated screw press, such as the vulcanizing
and matrix press, and is dried for a period varying from some minutes
up to half an hour. Some blotting paper is advantageously pressed
on top of the whole in the press while drying. The press is opened,
the flong removed, and dried in an oven. It is kept under a piece of
wire net while drying to keep it flat. The net may be of wire, .064
inch thick, with six meshes to the inch. This baking is not strictly
necessary for rubber stamp work.
This gives a matrix which may be used as rubber stamp moulds. In use it
is recommended to place a piece of smooth tin foil over it. This tends
to give a smoother surface to the rubber.
STRUCK UP MATRICES.
Didot’s polytype process may be advantageously used for producing type
metal matrices. The following is the method of applying it.
The type form is firmly locked and is backed up by and secured to a
solid block of wood. It is suspended in a sort of gallows frame with
the face of the type downward and exactly level a few inches above a
table. Underneath it a shallow tray is placed, into which some melted
type metal is poured. The melted metal is carefully watched. The block
and type are held by a catch so as to be released at will. Just as the
type metal is on the point of solidifying, the block is released and
drops upon the metal in the tray. The type should be slightly oiled.
The force of the blow produces a matrix in the metal, and the form can
at once be removed.
It is well to have accurately adjusted distance pieces for
corresponding striking pieces on the type block to impinge upon. The
process is highly spoken of, especially for small forms such as those
mostly required for rubber stamps.
CHALK PLATES.
The base for this form of matrix is a metal plate whose surface is
slightly roughened with sand-paper. It is next rubbed over with white
of egg, and flooded with the chalk wash made as follows: Flong paste
(described under Papier Maché Matrices, page 80), six ounces; whiting,
twenty-four ounces; water, three pints. The whiting is softened by
soaking for an hour or more. The whole must be intimately mixed. It
should cover the plate to the depth of one-thirtieth to one-twentieth
of an inch. The plate is dried in a perfectly horizontal position.
When dry the design or writing, etc., is made with a smooth steel
point, the lines being carried clear through the white layer to the
metal. The mould is now baked at a temperature well above boiling
water; as high as 392° F. (200° C.) may be reached without harm.
If the coating seems too thin, an extra coat can be given between the
lines especially over the larger areas. This must be done before the
baking. A pipette may be used for putting on this coat. This deepening
has the bad effect of increasing the chance of the coating stripping
from the metal.
The matrix thus prepared is used in the press just as is the ordinary
plaster matrix. It is suited for reproduction of autographs, scrip,
diagrams, etc.