Many enthusiasts of purple clay pots favor those with more vibrant colors, which catch the eye and are very appealing. Particularly popular are black purple clay pots. However, in naturally mined purple clay pots, there is no true black.

Black purple clay pots come about under only two circumstances: one involves adding chemical substances, such as manganese oxide, to adjust the color of the clay; the other is achieved through a special firing technique known as "smothering with ash." Naturally black clay materials have existed and were once exported in large quantities, but these types of clay are now rarely seen.

It-s common to see names like "Black Gold Sand," "Black Iron Sand," and "Black Clay" on the market, all of which are very attractive. In reality, these names refer to clays that have been colored by adding manganese oxide.

(Black Gold Sand, colored with manganese oxide)

Another possibility for black purple clay pots is "smothering with ash," a unique method of firing. After an initial firing, the pot is placed in a low-temperature, oxygen-deprived environment and burned alongside charcoal. This causes a reaction between the charcoal and the iron elements in the clay, altering the state of the iron ions and turning the pot black. Therefore, the black color obtained through smothering with ash is natural and harmless, as no harmful chemicals are added; it simply changes the state of the iron ions in the clay.

The black produced by smothering with ash is fundamentally different from that created through chemical coloring. Upon close examination, the colors are distinguishable. The black from smothering with ash is bluish-black, with a hint of blue or green, not a deep, pure black.

(Shouzhen Duiqiu smothered with ash)

Not all types of clay can be successfully smothered with ash. Generally, only purple clay varieties are suitable. Zhuni (red clay) has a high degree of crystallization and a low success rate when smothered with ash. On the other hand, duan (segmented) clay, due to its loose structure, easily develops uneven coloration during the process.

When encountering unusual clays, if you cannot confirm what additives the seller has used, it-s best not to buy them. It-s recommended to choose naturally mined clays and avoid those with colorful hues.

Source: Encyclopedia of Purple Clay Pots, information is valuable when shared. If any copyright issues arise, please contact us for removal.