cast

In letterpress and relief printing, casting meant reproducing a type form or wooden engraving by pouring molten metal into a mold taken from the original. The caster would create a papier-mâché or plaster mold, called a flong, from the raised surface of type or artwork, then pour stereotyping metal (usually an alloy of lead, tin, and antimony) into it. The result was a solid metal plate that could be locked into a printing press and used for thousands of impressions without wearing the original.

Two distinct processes fell under this term. Stereotyping produced flat or curved plates from type and engravings, using the flong method at temperatures around 350 to 400 degrees Celsius. Electrotyping, developed later, used electroplating to build up a thin copper shell over a wax or lead mold, then backed it with lead or type metal. Electrotyped plates held finer detail and lasted longer, making them preferred for high-quality and long-run work by the early twentieth century.

Casting allowed printers to preserve original artwork and type from constant press wear, and to distribute multiple copies of a form to different print shops without shipping the original. A newspaper could cast its front page type into a plate, send the plate to branch offices or affiliates, and keep the original type in the composing room for revision. This workflow depended entirely on casting technology.

The term is now archaic in active printing shops. Digital prepress and polymer plates have replaced metal casting in commercial work, but the vocabulary persists in print history, in foundry work, and among letterpress practitioners. Understanding casting is essential to understanding how industrial printing scaled before offset lithography became dominant in the mid-twentieth century.