Underglaze printing by hot press

Underglaze Printing by Hot Press

This technique was developed at Worcester in the 1750s for printing in a single colour, blue. Brown and black printing was developed in the 1790s. Several other colors for underglaze decoration became available in the 1820s, and the technique was adapted for multicolor printing using a single copper plate.  In the 1830s it was adapted for multicolor printing using multiple plates. By this time it was also possible to print a continuous flow of pattern in a single colour by cylinder printing. The technology was also dependent on improvements in the manufacture of tissue paper, and sources of the blue pigment cobalt.

For the single-color technique read Thomas Battam’s account of 1851, or the following description.


 Stage 1: engraving or etching the copper plate

 The first stage was to engrave the design into the surface of a copper plate. Engraving means cutting into the metal with a sharp steel tool called a burin. Sometimes the plate was etched as well as engraved. Etching uses acid to bite into the surface of the copper. The plate is first coated with a wax which protects it from the acid and is known as a ‘resist.’ The design is then lightly scratched through the wax. The plate is then exposed to the acid. The acid bites into the copper wherever the design has been scratched through the wax. The result of both engraving and etching is a plate with the design cut into its surface.

 Stage 2: transferring the design from the copper plate to the tissue paper

 The printer heated the copper plate and rubbed a mixture of pigment and a heavy, sticky oil into the engraved lines. Heating the plate made the mixture run better into the lines. The printer carefully wiped the mixture off the surface of the plate, leaving it only in the lines. The printer took a sheet of tissue paper dampened with a mixture of soft soap and water. He placed this on the plate and passed the two together through a hand-printing press. This transferred the sticky mixture from the copper plate to the tissue paper. The paper was then carefully peeled off.

 Stage 3: transferring the design from the tissue paper to the pot

 The next stage was to trim the printed paper with scissors so that the design would fit the pot. Then the paper was placed on the pot and rubbed hard to transfer the sticky design on to the pot. The paper was then washed off.

 Stage 4: fixing the print on the pot

 Because the print was applied to the pot before it was dipped in glaze, this was an underglaze print. It was given a very light firing known as ‘hardening-on’, before the pot was dipped in glaze and then fired at high temperature, usually at least 1000 degrees Celsius. The print was then protected by the fired glaze and would not wear off.