[Keep Warm with a Yutanpo on Cold Days]

The cold days are still continuing. When it is cold, our bodies tend to shrink and tense up. As we spend more time indoors, how are you all dealing with the cold at home?

During the cold winter, a “yutanpo” (hot water bottle) is something we simply cannot do without. We cannot get through winter without one. Especially when going to bed, we always tuck it into the futon; it is so cold that we can hardly sleep without it. It also keeps us warm while sitting at home working or reading. It is wonderful how it provides warmth for a long time without using electricity.

The one we use at home is a common corrugated galvanized iron yutanpo, and there is a meaning behind those “waves.” As you know, a yutanpo is a heating device that stays warm by filling it with hot water, but the internal pressure changes as the temperature of the water changes, which can cause deformation or damage. To prevent this, the surface is corrugated to increase strength. This shape also increases the surface area in contact with the air, enhancing the heating effect.

Furthermore, the yutanpo was introduced from China during the Muromachi period. At first, many were made of expensive copper, making them inaccessible to common people. Therefore, the mainstream yutanpo that spread among commoners during the Edo period was made of ceramic rather than metal. While galvanized iron yutanpo were mass-produced and became popular during the Taisho period, ceramic ones were re-evaluated when metal became scarce during the war. Recently, plastic versions have become common and easy to use, but ceramic remains superior in heat retention and is said to have far-infrared effects. Indeed, when we used a ceramic one before, the water cooled down slowly, and the warmth lasted for a long time.

The yutanpo available at Shokunin.com is made of porcelain by Ceramic Japan, called “yutanpÖ,” which is well-known for its heat retention. What is noteworthy is that this yutanpÖ does not have the “waves” mentioned earlier. It is designed to withstand decompression, resulting in a smooth, beautiful shape that showcases the sleek texture of porcelain. It is also convenient that you can fill it with tap water (after removing the aluminum cap) and heat it in a microwave.

There are yutanpo made of various materials such as rubber, galvanized iron, and plastic. Finding one that fits your lifestyle makes it a reassuring ally in winter. We are also being kept very warm by our yutanpo this winter.

Ceramic Japan's yutanpÖ
https://www.shokunin.com/en/ceramicjapan/yutanpo.html

Reference
https://ja.wikipedia.org/wiki/湯たんぽ