Is there sustainable ceramic tableware?

Have you ever thought about whether your tableware is sustainable? If you do some research on the Internet, you'll find surprisingly little information about it - in the case of ceramics, the topic of sustainability hardly seems to be discussed yet. That's precisely why we've taken a closer look at it.

The raw materials: Is clay sustainable?

First of all, we must note that clay is a natural raw material consisting of several mineral elements. As such, clay is mined and as long as it is not fired, it can always be restored to its original state. This means that pottery objects that break before the first firing can always be "re-sumped" with water and you can work with them all over again. This applies to both hobby potters and industrially produced ceramics.

Can fired clay be recycled?

In order for objects made of ceramics to become hard and thus usable, they must be fired. This is usually done in two firings, the so-called low firing (biscuit firing) and the high firing (somewhat simplified). After the first firing, the objects are solid and can be glazed. This means that when the objects come into contact with liquid, they no longer soften. From this stage, ceramics can no longer be returned to their original clay form. 

How to recycle fired clay (ceramics)?

In the true sense of the word, clay cannot be "recycled". However, since costs are also incurred in industry due to broken fired clay objects, attempts are also made here to continue using fired clay. This is done in industrial production by finely grinding the fired clay and then adding it to the new clay as so-called "chamotte". This promotes the structure of the clay objects and is therefore helpful in the production of new ceramics. Such "ceramic sand" can also be used for the production of glazes.

Can glazed ceramics be recycled?

After the raw firing, ceramics are usually glazed. For this purpose, a mixture of various minerals mixed with water is applied to the clay vessel. During firing, the object is heated until the minerals begin to melt and a "glass layer" forms on clay bodies - the glaze. Glazed objects can no longer be ground and used as fireclay. So, in the strict sense, glazed ceramics can not be recycled. 

How to reuse broken ceramics?

Unfortunately, broken tableware is not suitable for the production of new ceramics. However, there are ways to further use ceramic waste:

• Glazed ceramics can be ground into sand or gravel and added to other building materials such as cement, for example.
• Broken into shards, ceramic waste can be used for mosaics or to make terrazzo.

What is the CO2 balance of ceramics / tableware?

Basically, one must again distinguish between hobby potters and industrial ceramics. Hobby potters usually work with electrically operated turntables and electric kilns. The main share of energy here is therefore caused by electricity - and this is not insignificant when firing. As a rough guide, a medium-sized kiln generates electricity costs of approximately 30-40 Swiss francs per firing. Efficiency can be increased here by layering as well as possible and placing many objects in one kiln (do not run a half-full kiln). The decisive factor for sustainability is therefore where the electricity comes from to run the kiln.

In more professional factories or in industry, however, gas kilns are used. In a normal kiln in a Portuguese ceramics factory, there is room for about one euro pallet of goods (stacked about 2 m high). Natural gas is used here instead of electricity. Natural gas is per se less environmentally friendly than (green) electricity, but is used as standard due to better technical results. By the way, the gas in Portuguese factories comes primarily from Algeria. By the way, gas is also one of the biggest cost points in the production of ceramics - so with the current gas prices one should not be surprised if tableware becomes a bit more expensive...

What CO2 emissions are generated in the production of ceramics?

Basically, we can distinguish between the following processes:

• Manufacturing process before firing: Here, only a few emissions are produced, since, for example, a lot of casting is done without electricity. The preparation of the clay as well as the operation of turntables causes low electricity costs. The CO2 emissions here depend on the power source.
• The biggest factor in production is the raw and glaze firing. Here, for example, energy is saved by firing the glaze at below 1200°. This reduces the overall firing time and the amount of gas required. 
• Another important factor is the transport route. Short transport routes (ceramics from Europe vs. ceramics from China) cause fewer CO2 emissions and do not pollute the sea.
• How do the ceramics get to you? Do you go to the store by car or by public transport? Even if you order ceramics by mail, there are often long transport routes - packages are usually first sent to a distribution center, from where they reach you.

How can ceramics be made more sustainable?

Basically, the most important factor we can influence is the useful life of our tableware. Therefore, we focus on high-quality produced, robust tableware in timeless colors. Of course, it's always hard to estimate whether you'll still like the tableware in a few years, but it's worth thinking about whether you want to eat out of a garish pink bowl every day. Our own dinnerware is therefore deliberately designed to present food in the best possible way. In our experience, gray, blue or white contrasting colors work best to show food in the best light.