purple clay is a thin layer found within the Jia clay ore, and due to its higher iron oxide content compared to Jia clay, it turns purple or dark brown after firing, making it the primary material for crafting purple clay teapots. Purple clay can be further divided into purple clay, red clay, and green clay. Within the category of purple clay, there are also subtypes such as purple clay, Dicaoqing, Hong Pilong, Bai Pilong, Hong Mazi, and Bai Mazi. These three base clays are like the primary colors in painting, capable of producing an infinite variety of hues through different ratios of mixing.
The color variations of purple clay achieved through different mixtures of these three base clays and firing temperatures are considered natural and additive-free. This is similar to how we would refer to fabrics dyed with natural plant pigments by ethnic minorities as naturally colored coarse cotton cloth.
The color changes in purple clay are related to the types and proportions of metal oxides present in the clay. After firing, the clay can display a range of colors including sky blue, dark Liver, hibiscus red, vermilion purple, aquamarine, sunflower yellow, pear skin, pomegranate Peel, dark green, light ink, and indigo, among others. The artisans have always kept the methods of mixing the clay colors secret, considering them valuable trade secrets passed down through generations.
People's understanding of mixing purple clay has evolved over time. In the early days, without the concept of chemistry, the colors of purple clay were obtained solely through mixing different clays. Later, with the introduction of chemical elements, people discovered that adding iron produced red, manganese produced black, and cobalt produced blue. This was akin to when people preferred synthetic fabrics over cotton for their appearance. At that time, there were no concerns about issues like gutter oil, melamine, genetically modified foods, smog, formaldehyde, or lean meat powder, so additives that changed the color of the clay were accepted.
This practice continued until the 1990s. As the popularity of Yixing purple clay grew, the price of raw materials increased. Some unscrupulous merchants, driven by profit, began using ordinary pottery clay mixed with chemical additives to imitate purple clay, leading to the creation of harmful “chemical teapots.” After the 2009 Yixing purple clay scandal, there was a renewed interest in natural products, and there was a demand for teapots made from pure, unadulterated ore. While some coloring agents, like ferric oxide, can be added in small quantities without harm, in today's market and living conditions, there is a strong preference for teapots made from pure, natural ore. Consequently, high-end Teapot makers now prefer to use pure ore clays in their creations.
One teapot has been used for two days, while the other has not yet been used. Can you see the difference?
