First published July 17, 2019.
Pour soy sauce into one of these small white porcelain dishes and a picture appears: Mount Fuji, a Shinto shrine gate, a kitten or a puppy. Empty, each dish looks almost plain. Filled, it shows a detailed sepia-toned image that looks like an old photograph.
The dishes are made by ReDeStu, a small Japanese studio that combines 3D printing with traditional ceramics. The trick is a carefully shaped relief in the bottom of the dish. Deeper hollows hold more sauce and look darker; shallower areas hold less and look lighter. Your eye reads those tones as a picture.
Below you will find how they are made, a closer look at each design, a short history of soy sauce, and what people said when the dishes went viral in 2019.
How the hidden pictures work
The effect is the same principle as a lithophane, the 19th-century porcelain panels that reveal an image when held up to a lamp. There, thinner porcelain lets through more light. Here, deeper porcelain holds more dark liquid. In both cases a single colour, controlled only by thickness or depth, produces a full range of tones.
Soy sauce is an ideal medium because it is dark, slightly translucent and runs smoothly into every hollow. A pale liquid such as rice vinegar would show very little.
How ReDeStu makes the dishes
The dishes are not printed directly. According to the maker, the original form of each design is produced on a 3D printer, which can reproduce the fine depth changes the image needs. A plaster mould is taken from that master, and white porcelain slip (liquid clay) is poured into the mould to cast each dish. The pieces are then given a thin clear glaze and fired.
The clay used is Seto ware, from Seto in Aichi Prefecture, one of Japan's Six Ancient Kilns. Potters have worked in Seto since the 13th century, and the town became so important that setomono, “Seto things”, is still a general Japanese word for ceramics. ReDeStu says the technique is patented.
In 2019 the dishes were reported to cost ¥1,080, about $10. The shop now lists each design at ¥1,430, with gift boxes and sets available. More information: redestu.buyshop.jp | Instagram.
The designs, dish by dish
ReDeStu currently sells five designs: the upside-down Fuji with cherry blossom, Itsukushima Shrine, a kitten, a husky puppy and a Shiba Inu puppy. The photos below show most of them both empty and filled.
The Itsukushima Shrine design, empty and filled. Without sauce the dish shows only faint white ridges; once the hollows fill, the great torii gate that seems to float off Miyajima island appears in shades of brown, complete with its reflection.
The same torii photographed from above. Because deeper hollows hold more sauce, they read as darker tones, while the raised parts stay pale, much like the shadows and highlights of a photograph.
The Mount Fuji design before pouring. In white porcelain the relief is barely visible: a subtle mountain outline with a spray of cherry blossom on one side.
Filled with soy sauce, the scene becomes the “upside-down Fuji” with cherry blossoms. The mountain and its reflection in a lake are a classic Japanese landscape motif, especially loved at blossom time.
The kitten dish, empty. The modelling of the fur and eyes is fine enough that you can make out the design if you tilt it to the light.
The kitten filled. Large eyes and whiskers emerge from the darker pools, so the cat seems to peer out of the dish.
A husky puppy, before the sauce goes in. The shop also sells a Shiba Inu puppy version, making five designs in all.
The husky after filling. The contrast between the dark mask and pale muzzle comes entirely from the depth of the porcelain.
Two dishes side by side, one filled. The comparison shows that there is no printed decoration at all; the image only exists when liquid is present.
A step-by-step sequence of the Fuji dish filling up. The picture builds as the sauce spreads, first the dark lower slopes, then the reflection and finally the blossoms.
An empty dish held in the hand, showing how small these plates are. They are mamezara-style condiment dishes, sized for a little soy sauce beside sushi or sashimi.
The full collection lined up: Fuji, the Itsukushima torii, the husky and the kitten, each repeated across a row. Seen together, the designs show how consistent the slip-casting process is.
See it happen on video
Watching the sauce flow in is the best way to understand the design. The image does not appear all at once; it develops from the deepest areas outward, rather like a photograph in a developing tray.
A short history of soy sauce
Soy sauce began in China. A fermented soybean paste, known as jiang, is recorded in the Han dynasty, and soy sauce in something like its present form dates back roughly 2,200 years. Older articles sometimes claim it goes back more than 3,000 years, but the documented history of the liquid sauce is shorter than that.
Buddhist monks brought soy-based seasonings to Japan in the 7th century, where it became shōyu. The Dutch East India Company began exporting Japanese soy sauce to Europe in 1647. The English word “soy” is usually traced back to the Japanese name, passed on through Dutch traders.
How it is made
Traditional brewing follows a few steps. Soybeans are soaked and cooked, and wheat is roasted and crushed. The two are mixed and inoculated with Aspergillus mould to make koji. The koji is then mixed with brine to form a mash called moromi, which ferments for months while enzymes, yeasts and lactic acid bacteria break down proteins and starches into flavour. Finally the mash is pressed, and the liquid is pasteurised and bottled. Typical fermentation runs from about three to six months, and premium sauces can age much longer.
The main Japanese types
- Koikuchi: the standard dark soy sauce from the Kantō region, made from roughly equal soy and wheat. It accounts for more than 80% of Japan’s production.
- Usukuchi: lighter in colour but saltier, popular in the Kansai region for keeping food colours bright.
- Tamari: rich and dark, made with little or no wheat, traditional in the Chūbu region.
- Shiro: “white” soy sauce made mostly from wheat, pale and sweet.
- Saishikomi: “twice-brewed”, made with soy sauce instead of brine, very dark and intense.
For these dishes, a standard dark koikuchi gives the strongest contrast. A pale usukuchi or shiro would produce a much fainter picture.
What people said online
When photos of the dishes were shared online in 2019, the reaction was almost universally delighted. A few of the comments are below.
Reader comments: one simply asking for the sauce, another praising the idea and noting that even the ripples in the water are rendered so the result looks like a photograph, one insisting the dishes are far more than mildly interesting, and a last one calling them brilliant.
The dishes are a good example of design that uses an everyday material in a clever way. There are no screens or moving parts, only porcelain shaped to the right depth, and the image is completed by the meal itself.
Sources: ReDeStu official shop; ReDeStu on Instagram; Wikipedia: Soy sauce; Wikipedia: Seto ware.
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