Lithophane

A lithophane is a thin panel made from a see-through material, most often porcelain, that has been shaped with varying thickness. When a light shines from behind, these differences in thickness create a range of shades, revealing a picture. The image only appears correctly when backlit. These objects were invented in the 1800s and quickly grew in popularity, commonly used as lampshades, nightlights, or hung in windows. They could also be placed on stands in front of a light source. Typically, the longest side of a lithophane measures between 6 and 10 inches (15 to 25 cm).

The subjects chosen for these images were often artistically conservative, mostly copying designs from prints or paintings via reproductive prints. Many depicted sentimental domestic scenes, though portraits, landscapes, and religious themes also appeared. The technique naturally produced images only in shades of grey, known as grisaille, but later examples were sometimes hand-painted with translucent paints, like watercolors, to add color. The name comes from Greek: *lithos* meaning "stone," and *phainen* meaning "to cause to appear."

Invented in France during the 1820s, lithophanes quickly spread and were produced in several countries. However, Germany soon became the main manufacturing center and remained so for the rest of the century. The largest producer was the Prussian Königliche Porzellan-Manufaktur (KPM) in Berlin, which led to the English term "Berlin transparencies." Another major manufacturer was the Plauesche Porzellanmanufaktur in Plaue, Thuringia, Germany, which continued production into the second half of the 1900s. Their peak production period was roughly from 1840 to 1870. By the end of the 1800s, lithophanes had largely gone out of fashion, but in recent decades they have seen a revival, using materials beyond porcelain, such as glass, plastic, and even paper with 3D printing.

**Technique** To make a porcelain lithophane, a wax plaque was placed on a glass backing and carved. By lighting it from behind, the developing image could be seen, much like the final product. A plaster of Paris cast was then taken from the wax, creating a reusable mold for the porcelain. The finished piece was usually left unglazed as biscuit porcelain. As production increased, more durable metal molds were often used. Because the porcelain could be as thin as about 1/8 inch (3.2 mm), waste from breakage during firing was high, sometimes reaching up to 60%.

**History** There were earlier precedents in Chinese porcelain, using a technique called *an hua*, meaning "secret" or "hidden decoration." However, this was typically done by scratching or engraving the unfired porcelain body and was mostly used for floral patterns or text inscriptions, often Buddhist, rather than the narrative images common in Western lithophanes. It was also mainly applied to closed vessel shapes like vases and teapots, suggesting backlighting was not the intended purpose.

The European technique was invented by French diplomat Baron Paul de Bourgoing (1791–1864), who patented it in 1827. His friend Baron Alexis du Tremblay owned a pottery on his estate at Rubelles, where the earliest examples were made. Since de Bourgoing felt it was inappropriate for a diplomat to use his name in commerce, these lithophanes were marked "AdT" (for Tremblay's name). Other factories quickly adopted the technique, many under license from de Bourgoing. Meissen porcelain began making them in 1829 and had produced tens of thousands by 1850. Besides Berlin and Plaue, other manufacturers included Volkstedt, St. Petersburg, and Royal Copenhagen. An English patent, licensed from Bourgoing, was granted in 1828 to Robert Griffith Jones, who then sub-licensed it to English factories such as Mintons, Copelands (later part of Spode), and Grainger's Factory in Worcester (later merged into Royal Worcester). By the end of the century, the fashion had largely faded, though lithophanes were made to commemorate the Coronation of Edward VII in 1902. By the mid-1900s, the technique was used in Japan, mostly for gaudy tea sets made for American soldiers after World War II, featuring a lithophaned face of a geisha at the bottom of the cups.

**Modern Lithophanes** Porcelain lithophanes are still made in limited numbers by studio potters and large manufacturers like Bernardaud and Wedgwood. Similar effects can be achieved with molded colored glass, though these are not typically called lithophanes. The term has been revived for images created by digitally controlled cutting (CNC), a subtractive process, or by 3D printing, an additive one. Many companies now offer to make one-off images or sell the equipment to make them, and solutions exist to add color to these. One early pioneer of modern 3D-printed lithophanes was artist Jonty Hurwitz, whose 2011 artwork *Physics is Funny* used early additive manufacturing to create a 3D lithophane. Initially, creating these required complex manual processes to map 2D grayscale values into physical height variations. Open-source maker communities followed manual conversion workflows, but the process was automated in April 2013 when MakerBot released a browser-based "Customizable Lithophane" tool. In 2015, developer Mark Durbin launched the open-source web generator 3dp.rocks, which widely popularized the medium by allowing users to easily render images into 3D meshes. Modern consumer 3D printing mainly uses two technologies for lithophanes: fused deposition modeling (FDM), which uses standard thermoplastic filaments like white polylactic acid (PLA) extruded layer-by-layer to control light transmission, and stereolithography (SLA), which uses liquid photopolymer resins cured by light. SLA printing enables microscopic layer resolutions, achieving smooth, high-fidelity results.