printing plate for Dana Girls book
 Example of a copper-clad electrotype printing plate used for The Clue of the Rusty Key (©1942) in the Dana Girls series. The plate has a copper printing surface and a heavy backing metal (overall 1 lb.).

How a Series Book is Printed

When series books were published, it was expected that thousands of copies would be printed and sold.  The lead-based type metal (actually lead, tin and antimony) was too soft and heavy for a page’s worth of type.  

The electrotype printing plate was one of two main methods used to make plates for books (and other kinds of printed matter).  The other was stereotype which was mostly used in the newspaper field.

Trixie Belden manuscript pages
 Two pages from a complete typed manuscript for a Trixie Belden book (not Syndicate) with hand corrections in color by a couple editors on staff.
Linotype machine
Linotype machine at the International Printing Museum in Carson, California.

After a book manuscript is edited and provided to the typesetter, a line-casting machine is typically used.  The Linotype or similar produces a line of type cast in type metal after the operator presses keys for each letter.

The keyboard is not arranged like a familiar typewriter.  Instead there are three sections of keys for upper case, lower case, and numbers and symbols.  So different was this that special typewriters were made with this arrangement for use in print shops where the staff was trained in this configuration.

Brass molds or “matrixes” hold the shape of each character that is pressed on the keyboard.  These drop down, in sequence, to form the line.  When the line is complete, a lever is pressed and molten type metal is pressed into the series of molds.  The excess is trimmed off and the line of type is dropped into a receiving tray.

Printing Galleys and Proofs

A galley full of slugs from the Linotype machine.
A galley full of slugs from the Linotype machine.

When many lines have been produced, they are placed in a galley tray and inked.  A long piece of cheap paper is placed on top of the inked type and a heavy roller presses the paper down to pick up the ink.  When the paper is lifted, it forms what is called a “galley proof.”  If it initially looks OK to the printer, it is sent off to the author (or syndicate) for correction.  Flawed lines will be replaced with the Linotype machine.

The next stage involves dividing the lines of type into pages, adding the page numbers and running head text.  From these page proofs are printed.

 These page proofs are corrected again with special attention given to the optimum number of pages overall and lines for the last page in a chapter.  If necessary, replacement lines can be created with the Linotype.  

When as perfect as possible, the proofs are marked “F” for “final” or “foundry” and electrotype plates are made.

Electrotype Printing Plate is Created

A mold is taken by pressing wax or another material against the type metal lines.  From this the mold is treated with a conductive material like graphite.  The mold is connected to one side of a battery and placed in an electrolytic bath.  The other side of the battery (or DC power source) is connected to a copper source.  After some length of time, copper is deposited on the graphite in the mold.  When enough of this has gathered, it is removed from the bath and a backing added.  The overall page plate is trimmed and beveled to create the copper-clad electrotype printing plate seen above.

A plate like this is needed for every page in a book with ink on it.  Each one weighs about a pound.  Between print runs, these are placed in crates and the crates stored in vaults.  It is important to protect them from corrosion, physical damage, or being placed out of order.

 The Clue of the Rusty Key (Grosset & Dunlap, 1944) in the Dana Girls series.

Printed and Gathered

For use, the plates for many pages are installed in a form in a particular order and orientation according to the number of pages printed on each side of a sheet.  When printed, these sheets are folded and trimmed and form a “signature.”  Several signatures form the page block for a book.  

As these are gathered, a signature with advertisements is added to the stack for binding.  This is the reason that post-text ads in a series book are a clue to the vintage of the binding.  The publisher liked to have as many of the available titles in a series advertised as possible.  Thus, if the ads were recently printed, the last title on them will reflect the approximate binding date for the book.  Dust jacket listings were changed even more frequently and are a more precise estimate (if the book and jacket were kept together throughout the book’s life).

The printing plate here for a volume in the Dana Girls series was used on every U.S. printed copy—potentially tens or even hundreds of thousands of copies.  Usually this kind of item was melted down, especially during shortages such as World War II, so having a survivor like this is fairly unusual.