By Robert D. Servoss.
Almost all of the maps found in text and reference books, as well as
the geometrical diagrams used in mathematical and scientific works,
are made by what is known as the "wax process."
This process was invented and patented by an Englishman named Palmer
about 1840, shortly after the discovery of the method of making
electrotype plates for printing purposes. He announced that he would
furnish artists with copper plates covered with a waxlike composition
on which they could make their own drawings, in a manner similar to
but much simpler than the method followed by the etcher on copper.
After receiving the artist's work, the plates were to be returned to
Palmer, who then made an ordinary electrotype of the engraving. A
circular, issued about 1841, gives the necessary instructions for
engraving, and the prices for the wax-coated plates and the subsequent
electrotypes, and shows many beautiful illustrations made by artists
of that time. It was then called the "glyphographic process."
The process was first introduced into this country by a firm of
printers in Buffalo, New York, and was used by them for several years
for illustrating the United States patent office reports until it was
superseded upon the introduction of photo-lithography and the
subsequent adoption by the government of a uniform standard for patent
drawings.
This process may be described in a general way as follows: A copper
plate having a highly polished surface is first blackened by the
application of a weak solution of sulphuret of potassium, or other
chemical which will oxidize the copper. Then a composition, made by
melting together in proper proportions, beeswax, zinc-white, and
paraffin, is "flowed" over the blackened surface, producing an opaque
whitish engraving ground. The thickness of the wax is varied according
to the subject to be engraved, but in general should not exceed that
of heavy writing paper. After it has been allowed to cool with the
plate lying perfectly horizontal, the wax is smoothed down to an even
thickness by a steel scraper, and the plate is then ready to receive
the engraving.
Taking for an example the engraving of a map, the original copy is
either photographed on the wax surface, or is transferred to it by
covering the back of the copy with red chalk and tracing over every
line with a steel point. The photograph, or the tracing, on the wax
must not be a reversed one, as might be supposed, but should "read
right." The outlines of the map are then gone over, with an engraving
tool which cuts out a small channel in the wax, down to, but not
into, the surface of the copper plate. The bottoms of these channels
will eventually form the surface of the relief lines in the resultant
electrotype plate, but now appear as dark lines against the whitish
groundwork of the wax.
The engraving tools are made in different sizes, and therefore
channels of varying widths at the bottoms may be cut in order to
produce lines of different sizes. In cutting lines to indicate
rivers,--which must be thin at the source and increase in thickness as
they approach the mouth,--tools are used in graduated sizes. The first
one cuts its own line of equal width for a very short distance, then
another and slightly wider tool is used, the next still wider, and so
on until the river line is completed. In reality a series of steps,
the work is so done that the line appears to the eye to increase in
width evenly and gradually from a very fine beginning to a heavy
ending. The wavy lines indicating hills and mountains are made in
substantially the same way. Special steel punches are pressed through
the wax to the copper to show town and capital marks, and after all
the lines and marks are completed, the plate is ready to receive the
lettering. The name of each individual town, city, state, or river is
set up in printer's type and stamped one name at a time into the wax.
The type is placed in a small tool resembling a vise, which holds it
in perfect alignment and on a perfect level. Tools of various shapes
are used for stamping the names in straight and curved lines. It is
necessary to wet the type to prevent its adhering to the wax.
The plate is then carefully compared with the original copy and after
any necessary corrections have been made it is gone over by an expert
operator, who cuts out any of the channels which may have been
obliterated by the burr of the wax, resulting from pressing in the
names.
We now have a plate in which the lines have been cut in small channels
and the names stamped with type. This is a matrix, or mould, from
which an electrotype of the lines now sunken in the wax may be made in
high relief for printing, but the blank portions of the wax are so
thin that it is first necessary to fill in all these places on the
plates with wax in order to produce a sufficiently deep electrotype
plate. This is done by "building up" the plate. A small hook-shaped
tool, heated over a gas jet, is used to melt small pieces of wax which
are run carefully around all the names and in the spaces between
lines, thus filling up all these spaces with a round, smooth body of
wax. From this mould an ordinary electrotype is made by the method
described elsewhere in this book.
All these operations require much skill and patience at every step,
but the plates produced by the wax process are always much deeper and
stronger than those made by any other process.