The tatami is large made up of three parts. One is a “tatami facing” that is the part on the surface of tatami, a “tatami bed” that is the padding of the tatami, and a “tatami edging” that is cloth sewn to the tatami to protect its edge.
The tatami facing is made of mat rushes woven into the warp and is the same as rush matting. Cotton yarn and hemp yarn are used for the warp. Using a strong warp makes it a good “tatami facing” with high cushioning properties. It is also the part that is in direct contact with people, and the part that is damaged most easily, so by renewing it regularly you can prolong the service life of the tatami.
The “tatami bed” is the part that becomes the padding of the tatami and is made of many layers of rice straw. However, few “tatami beds” have recently been produced using genuine rice straw. Tatami made with genuine rice straw are regarded as the top-end goods and used in shrines and temples, luxury houses, old houses that have been in existence for a long time, and so on. What is used in ordinary households is “rice straw sandwich tatami beds,” where a board of polyethylene foam is sandwiched between layers of rice straw, and “tatami beds of building materials” made of insulation boards of compressed wood chips and polystyrene foam. Because “tatami beds” made of chemical materials are less likely to be infested with mites and other bugs and they also have high heat insulating properties, in new houses in particular, “tatami beds of building materials” seem to be used a lot.
The “tatami edging” is the textile part sewn to the long sides of the tatami to prevent the corner parts of the tatami from being damaged. In the samurai era, applying colors and family crests to the edging to indicate one’s identity symbolized status, but these days, most people choose edgings with their favorite colors and designs. There are various kinds of edging designs, from traditional Japanese designs to patterns that also match Western-style interiors.