What is Shoji?
When you hear the word 'shoji' (pronounced 'show-jee'), in modern Japan, shoji means wooden sliding doors with translucent paper on. These doors slide on wood tracks very smoothly and quietly, work as a room divider or window coverings.
The original concept of shoji was born in China, and was imported into Japan sometime between 7th to 8th centuries. The word 'shoji' indicates 'something to obstruct' in both Chinese and Japanese. At that time, it meant everything used as a room partition, including freestanding screen and fixed panel with paper or fabric on. So those freestanding shoji screens in the U.S. aren't too far off from the origin of 'shoji'. By the 12th century, shoji had evolved into something unique to Japan, the sliding doors lined with paper.
The Magic of Shoji Paper
The paper is translucent and is called 'shoji paper'. Sometimes people call it 'rice paper' (since it sounds 'oriental'?), but shoji paper really has nothing to do with rice.
Traditionally shoji paper was always 'washi' (=literal translation is 'Japanese paper'), commonly made of these 3 kinds of materials, Japanese mulberry tree called 'Kozo', or shrubs called 'Mitsumata' and 'Ganpi'. The paper was scarce and valuable because it was all natural and hand-made, until manufacturing of shoji paper began in late 1800s. The use of synthetic and chemical fiber started around 1960s, making the paper very affordable.
What made shoji so great and popular, has a lot to do with what the shoji paper does. Because of its rough texture, this paper refracts and diffuses lights. The paper filter intense sunlight and throw a nice soft glow even on the hottest summer day. When privacy is needed, you can close doors without making the room too dark. Sound can be still heard, but all you can see from the other side is just a silhouette....
Elements of Shoji
How does the sliding system work? Top rails run between corner posts that support beams. Bottom rail lies on the floor, sticking about a half inch. There are deep grooves in the top rail and shallow grooves in the bottom. Grooves are slightly narrower than the door stile thickness. The top and bottom of the doors are cut with a matching L-shape tenon, and they slide along the groove smoothly. The doors are so light you can open it with one finger. The doors can stay opened or closed, depending on the privacy level you want. If you need a one big room for a gathering, doors can be taken off the rails and put away. This sliding shoji door and track system worked so well in traditional Japanese house, because a house used to have only one large room with no permanent walls, in the old times. Talking about an open concept floor plan!
Another important element of shoji is the lattice work, or 'kumiko' (translates 'woven'). The clever structure of shoji only need minimal amount of material (wood and paper) and yet pull out each material's possible strength to a maximum. Since wood pieces are inter-woven, they become a lot stronger and sturdier. Simple geometric pattern actually stabilize outer wood frame and also keep the paper tension. It is something that seems to have only aesthetic value but it is actually the core of strength and functionality. Because of kumiko, shoji is delicate, beautiful, light, and strong.
In conclusion, besides its aesthetic role, shoji
is a temporary room divider, a privacy screen and a light diffuser.
So then, How do shoji rails work?
Traditional Japanese sliding doors and track system used to be made of just natural material, wood and paper. Shoji is changing to fit in modern lifestyles, but the basic idea of the track system remains unchanged.
Inside of a traditional Japanese house, there are very little permanent wall. Rooms are separated by corner posts that support beams. If there is a typical 6 feet wide opening, there would be two panels of 3 feet (plus a stile width) wide shoji door. One track is on the floor and the other track is at the top. The top rail is attached to the bottom side of a beam. Two grooves are cut on each rail. The top grooves are 5/8 inch deep and the bottom grooves are only 1/16 inch deep. The top and bottom of the doors are cut with a matching L-shape tenon, and they slide along the groove effortlessly.
(Figure 1) 2 panels on 2 grooves
Two panels on two grooves (Figure 1) slide and pass each other. When open, that means two panels on one side stacking over another, there is 3 feet opening at maximum. When closed, the width of the stile is overlapped in the middle, so you won't see any crack of light in between two doors, covering 6 feet altogether.Another common pattern is four panels on two grooves (Figure 2). From left, the first panel on groove A, the second panel on groove B, they can pass each other. The third panel is also on groove B, butts against the second panel. The fourth panel on groove A, so the third and fourth are mirror reverse from the first and second panels. The second panel slide to the left and the third panel to the right, making the full opening of 6 feet. When closed, the four panels take up 12 feet.
(Figure 2) 4 panels on 2 grooves
Two above are common and traditional in Japan, but there are so many variations possible. For example, instead of stacking one over another, they can open to both sides and slide along adjacent wall surfaces on a single track (Figure 3). When closed, they meet in the middle, much like the two middle panels of four-panel-system above. This can be done when there is enough space on the wall. Even if that's not the case, they can slide into a wall pocket making a shoji pocket door. These are not typical but innovative ways to implement shoji into western style homes, which is more popular among new generations in Japan.
(Figure 3) 2 panels on 1 groove