How Spode blue happens: the transfer printing steps behind Fort Vancouver’s dishes

A Spode plate's pattern is not blue when it is printed: it starts out dark brown, turns light purple after the first firing, and becomes the famous Spode blue only after glazing and a second firing. The National Park Service uses saucers to show each step, because transfer printed dishes are common finds at Fort Vancouver National Historic Site.

A Spode plate in a transfer print pattern called "Italian," found by archaeologists at Fort Vancouver. NPS photo.

Why Fort Vancouver has so much of it

Ceramic fragments often make up almost 25 percent of archaeological finds from the fort's fur trade era (1825 to 1860), and transfer printed pieces usually dominate. The great majority of those in the park's museum collection came from one maker, the Spode Company of Great Britain. The Hudson's Bay Company, which ran Fort Vancouver, had a nearly exclusive contract to import Spode's ceramics to its North American sites. The patterns engraved on the copper plates were used again and again, and many have names and production dates, which gives archaeologists a catalog for identifying artifacts and interpreting sites.

The steps

1. Engrave. An artist's drawing was engraved on a copper plate.
2. Color. Color made of inorganic metallic oxides mixed with oils was rubbed into the hot plate and the excess scraped off.
3. Press. Once the plate cooled, tissue paper prepared with a soap sizer was laid on it and both went through a press, forcing the paper into every line of the engraving.
4. Lift. The plate was heated again to dry the paper and soften the color, and the paper was peeled off with the print on it.
5. Place. Sections of the print were cut out and set on the unglazed earthenware vessel, which had had a first firing. The tackiness of the color held them in place. On a plate or bowl, the center design went on first and then the border, and the print was rubbed down with a brush lubricated with soft soap.

A plate with the tissue paper still attached. NPS photo.

6. Wash. The piece was immersed in water, which washed off the paper and left the print.

A saucer with the tissue paper removed. NPS photo.

7. Harden the print. A low-temperature firing "hardened on" the print, so the piece could be dipped in glaze without damaging the design. The color changes in the firing.

The print after the low firing. NPS photo.

8. Glaze and fire. The glaze covers the design completely.

A saucer glazed on one half only, to show how the white glaze hides the design. The color is not yet blue. NPS photo.

The piece was then fired to 1070 degrees centigrade.

The brilliant blue half has its final clear glaze; the darker matte blue half is unglazed, for comparison. NPS photo.

The well-known blue and white appears at the end. The reaction of the silica in the glaze with the cobalt in the color produced the famous Spode blue.

A fully glazed and fired saucer in the "Italian" pattern. NPS photo.

Sources

• National Park Service, Fort Vancouver National Historic Site, "The Transfer Printing Process for Ceramics" (https://www.nps.gov/articles/transferprintprocess.htm); rewritten in hubnx's own words. The page's percentage for Spode's share of the collection is garbled in the source and left out.