All of the materials used to create stoneware, earthenware, and porcelain come from soil.

Yet, it is important to remember that the production process itself is not particularly sustainable. Firstly, the mining of china clay alone leaves behind nine tonnes of waste for every one tonne of clay extracted. Secondly, to fire a kiln, you need quite a lot of energy. And most kilns are powered by fossil fuels. Kilns emit CO2, carbon monoxide, particulate matters, sulfur dioxide and black carbon which pollute air. These emissions can also negatively impact soil health. Moreover, once glazed and fired to over 1,100° C, clay cannot easily be reused, nor will it biodegrade.

What is more, chemicals for glazing can be toxic. Lead- and cadmium based glazing can be harmful for humans’ health if pottery is used as kitchenware (as it may leak into the foods and water). Among other potentially toxic elements occasionally added in glazing are barium, cobalt, nickel, and selenium.

There are not many eco-friendly alternatives to kilns.

In recent years, there appeared electric kilns which can be powered by solar or wind energy.

Another option might be using water and calcium carbonate nano powder to compact ceramics at room temperature. The research found that it is energy-efficient and does not cause as much pollution.

To reduce your carbon footprint, you can also use recycled clay and locally sourced materials.  As for the glazing, it could be made from wood and plant ashes. 

Material designer Sinae Kim created glazed from human urine, and designer Yoon Seok-hyeon coated ceramics with layers of resin instead of glazing. Thus surfaces became waterproof, and the pieces didn’t require firing.

To add more on the positive side, ceramics might be a good choice if you aim for longevity – as it endures for millennia. Although glazed pieces can't be recycled, they can be upcycled – for example, turned into tiles.

Read more on this medium in "Know your media" section.