Kiln-effects pots (窑变壶)

Kiln-effects pots, or pots that do not possess a uniform colour after the firing process had taken place in the kilns. The pots usually have two distinct colours due to changes in the kiln environment. As I could not find a suitable term for it, I will call it kiln-effects pots (in Chinese they are called 窑变壶). There are some articles in cyber space on this type of pots (how the pots are formed).

I ever bought a kiln-effects teapot during the 80s from an antique shop. At first I thought the non-uniform colour on the pot meant that the pot was a defective piece. It was strange to see a teapot having two colours. As I liked the pot very much, I bought it anyway (for quit a low price). Many years later, I found that there are actually people looking for such pots to collect. In other words, they become collectors' items. They said these pots are rare and unique. That really puzzled me. I even read that there are people who would try everything to fake the kiln-effects pots.


Kiln-effects pot

 

If you see carefully, the colour on the left is reddish brown while the colour on the right is greyish. You can tell that something must happen to the pot during the firing process. As the pot was probably made in the 60s, it could have been fired in a traditional dragon kiln where old techniques were employed in the firing process. Actually I love to use this pot to brew tea. As hot water is poured into the pot, the colour of the pot turns greyish black (a bit like twilight) and this is what I call the true purplish colour. The teapot has a name, imitate-ancient pot.

 

Kiln-effects pots were the results of early pots being fired in traditional dragon kiln (a long kiln where the firing process may take many days to complete) where wood was used  as the only source of energy. Here the workers controlled the kiln temperature by observing the colour of the fire in the kiln and feeding wood accordingly. Apart from skills and expertise (which were crucial) the success of the firing process depended on many factors such as availability of oxygen (to assist combustion of the wood and the conditions/environments inside the kiln.  Temperature and atmosphere are also contributing factors. As the kiln was not always operating in optimum conditions, occasionally too much oxygen might be present in the kiln causing some oxidation to take place on the wares. As a result, the fired wares would showed different colours on the surface (may also be due to the fact that different parts of the wares were exposed to different firing conditions).Incidentally, the Yixing clay needs to be fired to certain temperature before the clay colour can fully develop.

 

 

Today the dragon kilns had been phased out. All the pots are fired in electrical furnaces where temperature control is precise and firing conditions are very consistent. In the absence of surplus oxygen, there could hardly be any kiln-effects pots produced in electrically fired wares. Some prefer to use the term "baked in oven" as compare to "fired in kiln" when pots are made these days. 

 

As people are looking for this type of pots to collect, businessmen begin to fake the wares by artificially creating the environments and conditions necessary for colour changes to occur on the pots.