Lithophane

A lithophane is a thin plaque made of a translucent material. Most lithophanes are crafted from porcelain. The term comes from Greek words. "Lithos" means stone. "Phainen" means to cause to appear.

This name describes how the image behaves. At first glance, the plaque may look plain or white. The image only reveals itself when light shines from behind.

This happens through varying thicknesses of the material. Thicker areas block more light and appear as dark shades. Thinner areas allow more light to pass through. This creates a detailed image using different tones of grey, known as grisaille.

The process of making a porcelain lithophane is very precise. An artist begins by placing a wax plaque on a glass backing. They carefully carve the wax to create the image. During this stage, they can shine light through the wax to see the developing picture. This helps them ensure the thickness is correct.

Once the wax is ready, a cast is made using plaster of Paris. This plaster cast becomes a reusable mould for the porcelain. As production increased, makers often used more durable metal moulds instead. The porcelain is generally left unglazed, a state called biscuit porcelain. This work is difficult because the porcelain is often only about 1 mm thick. Because of this thinness, wastage during the firing process was high, reaching up to 60%.

There were earlier precedents for this kind of art. In China, a technique called "an hua" existed. This means "secret" or "hidden" decoration. However, the Chinese method differed from the European one. Artists scratched or engraved designs into unfired porcelain. These were mostly floral patterns or Buddhist text inscriptions. They were usually placed on closed vessels like teapots or vases. This suggests that a backlit view was not the original intention. The European technique was a distinct invention with a different purpose.

The modern European lithophane was invented by Baron Paul de Bourgoing. He was a French diplomat who patented the process in 1827. He worked with his friend, Baron Alexis du Tremblay. The earliest examples were produced at the pottery on Tremblay's estate in Rubelles. Because de Bourgoing was a diplomat, he did not use his own name for commerce. Instead, the lithophanes were marked "AdT" to honor Tremblay. Other factories soon adopted the technique, often using licenses from de Bourgoing. Meissen porcelain began making them in 1829 and produced tens of thousands by 1850.

Lithophanes became a massive global industry during the 19th century. They were used for lampshades, nightlights, or hung in windows. Germany eventually became the world's main producer. The Prussian Königliche Porzellan-Manufaktur (KPM) in Berlin was the largest manufacturer. Their work was so famous that people called them "Berlin transparencies." The Plaue Porzellanmanufaktur in Thuringia was another major producer. They continued making lithophanes into the second half of the 20th century. The peak of production occurred between 1840 and 1870. Other notable makers included Volkstedt, St Petersburg, and Royal Copenhagen.

In England, the technology spread through various licenses. Robert Griffith Jones received an English patent in 1828. He then provided sub-licenses to famous factories. These included Minton, Copelands, and Grainger's Factory in Worcester. While the fashion for lithophanes faded by the end of the 1800s, they remained important for special events. For example, they were made to commemorate the Coronation of Edward VII in 1902. Later, in the mid-20th century, the technique was used in Japan. There, they were often used for teasets for American soldiers after World War II. These sets sometimes featured the face of a geisha at the bottom of the cups.

Today, the art of the lithophane is experiencing a revival. Modern technology allows for new ways to create these images. Some people use 3D printing, which is an additive process. Others use CNC, which is a subtractive process involving digitally-controlled cutting. While traditional porcelain lithophanes are still made by companies like Wedgwood and Bernardaud, new materials are common. Makers now use glass, plastic, and even paper. These modern versions can also include added color. Many museums still hold important collections. The Blair Museum of Lithophanes in Ohio contains the largest collection in the world.