2000 years ago, the ancients used a wooden bucket for bathing. The other was a "ground pot" that warmed the water while washing. It was an iron product. The firewood under the pot could ensure the temperature of the bathing water. Both wooden buckets and "ground pots" are the origins of modern free standing bath tubs.
In fact, wood and lead lining were materials of the earliest bathtubs. Then marble bathtubs appeared. From the 18th century, people began to like metal bathtubs. Metal bathtubs were popular. The most common material in metal bathtubs was red copper tin plating. The biggest feature of this material is that it will not rust. Most people like it. In the separate bathtub, tin plating or even silver plating can prevent the bathtub from rusting. It makes the separate bathtub more beautiful. Some bathtubs use joinery as material. They are antique furniture. They are works of art. Some separate bathtubs are designed with backrests or cushions. Some adopt form of sofa chairs or benches. This separate bathtub can be used by one or two people. At the end of the 18th century, there was a famous wooden shoe bathtub. There were more than 20 metal parts on it. It became famous because of its shape. There was a funnel for filling water and a faucet for draining water on it. Its design became advanced.
The comfortable facilities of modern bathrooms began in Britain in the 19th century. Bathtubs that can take wave baths appeared and eventually became a closed bathroom. At the end of the 19th century, the "cast iron bathtub" appeared. Another separate bathtub made of another material was born. The cast iron bathtub at that time turned at right angles. It was not smooth and uneven in thickness. There were many defects. By the 1880s, craftsmen mastered the technology of turning uncomfortable right angles into round edges. A few years later, they solved the problems of uneven glazing and thickness. They improved the defects of such bathtubs. Cast iron bathtubs became a perfect product.
With the passage of time, the separate bathtub has developed. The materials of the separate bathtub have changed from wood to cast iron, ceramics, steel plates, acrylic, etc. There are many changes in shape. The purpose is to make bathing more comfortable and refreshing. The bathing spirit in the bathtub has passed through thousands of years. It makes bathing a relaxing thing, which is worth savoring.