Clay Culture: Sustainable Steps Yuliya Makliuk

Appears in the November 2024 issue of Ceramics Monthly.

If you would like to make parts of your practice greener, the following guidelines describe the factors that take a pot from highly unsustainable to more eco-friendly. 

As potters, how can we better care for our planet? If you feel concerned—or even guilty—about the carbon footprint of your ceramics practice, this article can help guide you toward more sustainable choices in making, firing, and selling pottery. It breaks down the main sources of carbon dioxide (CO₂) throughout the life cycle of a handmade ceramic item and compares different scenarios—from the least eco-friendly to the most sustainable mug. By identifying key hotspots, you’ll discover where small changes in your studio practice can lead to significant environmental gains. 

Depending on the aim of the study, an environmental footprint can be calculated using various indicators. The emission of CO₂ is one of the most popular metrics, known as the carbon footprint. Expressed this way, as of 2022, our global carbon footprint reached a staggering 36.6 billion tons of CO₂.¹ 

To make things even more complicated, there is also a way to calculate the environmental (or carbon) footprint not only for the production of a product, but for its entire life story—from raw materials extraction to manufacturing, shipping, usage, and end-of-life disposal. This method is called the Life-Cycle Assessment, or LCA. 

I decided to estimate the carbon footprint of an average, handmade, ceramic mug to identify hotspots and set some benchmarks. My definition of “average” is a 350 ml, or 12 oz, mug made from local stoneware clay body, thrown on a kick wheel, and glazed with commercial glaze. It undergoes two firings in a kiln using conventional electricity from the grid, reaching cone 6 (2232°F (1220°C)). The weight of the finished product is 350 grams. As some items come out of the kiln with defects, every tenth mug is discarded in this scenario. The mug is then packaged with plastic bubble wrap and a cardboard box, and shipped from Ukraine to the US by truck and airplane. Over a span of three years, it is used every third day, hand washed with detergent, and eventually discarded into the landfill, together with its packaging. Calculating the impact of each stage with LCA software, the total cradle-to-grave carbon footprint of an average mug is 7.5 kg of CO₂. This is equal to 0.1% of the average person’s carbon footprint.² 

Surprisingly, the stages undertaken in making the mug are responsible for a smaller fraction of the footprint, adding up to 1.9 kg of CO₂. This is the “cradle-to-gate” phase and includes raw materials, domestic transport, production, and packaging— everything that happens before the mug is sold. Among these, the most carbon-intensive points are firing (1.4 kg), packaging with plastic (0.3 kg), using a cardboard box (0.07 kg), producing frit (0.06 kg), domestic transporting of materials (0.06 kg) and extracting clay (0.04 kg). 

Other inputs, such as water usage, proved to be less than 1% of the footprint. The rest of the impact is influenced by what happens after the mug leaves the studio, including shipping, use, and disposal. Here, the biggest contributors are a cargo flight from Europe to the US (2.6 kg), heating water for dishwashing (2.2 kg), dishwashing detergent production (0.4 kg), and packaging decay in a landfill (0.3 kg). 

Does it make sense? Have I calculated correctly? The published LCA studies of handmade ceramics suggest a range of 0.7–3.1 kg per mug of 350 g. These studies only include the cradle-to-gate stages, everything that happens before the mug leaves the studio. Around 80% of this footprint is associated with kiln firing ceramics, using fossil fuels or electricity. 

So, my assessment is well within the magnitude range of similar research, and I will be using it for further analysis to identify the worst and best alternatives when developing sustainable studio ceramics. Now, let’s see what the most polluting pottery mug is. 

The Dirty Mug: Add Gold and Cobalt 

How can I make a “dirty” mug, environmentally speaking? I played with the LCA software and changed parameters to build a realistic scenario that would produce the most carbon and easily managed to raise the mug’s full footprint by 60%, from 7.5 to 12 kg CO₂ per cup. Let’s see what I tweaked and how it influenced the outcome. 

The dirty mug is made from imported German clay and frit (+0.1 kg CO₂), the glaze is colored by cobalt oxide (+0.1 kg), and liquid gold luster is applied for decoration (+2.2 kg CO₂). It is fired three times using coal-based electricity (+1.5 kg CO₂) and packaged in a box with polystyrene that is incinerated after use (+0.5 kg CO2). The discard rate for this scenario is 20%, where it is estimated that every fifth mug is defective. The cradle-to-gate, or pre-sale phase, in this scenario, had a carbon footprint of roughly 6 kg CO₂ and after sale another 6 kg. 

While the dirty mug is a worst-case scenario, it is realistic, showing just how easily our choices impact the environment. Admittedly, making things worse is often easier than improving them. Let’s see how much cleaner we can make an average mug and turn it into an eco mug. 

The Eco Mug: Raw Glazing and Wild Clay Slip 

After much reading, experimentation, and advice from colleagues, I came up with better alternatives to the “average” mug. These are achievable for studio use, practiced by me and other potters, and include changes in use and end-of-life. Running them through the LCA software decreased their overall carbon footprint by 45% compared to the average mug, bringing it down to 4.1 kg CO₂. So, what makes an eco mug? 

Firstly, I substituted 25% of the clay body with ceramic shards ground into powder, decreasing the need for raw material extraction and transportation. I switched the commercial frit glaze to a local, wild, low-fire clay slip. In terms of firing, I skipped the bisque firing and fired only once with a raw-glaze schedule. I also changed the packaging materials, from a new cardboard box and bubble wrap to reused cardboard and paper filler (remember dumpster diving?). In addition, the defect rate in this scenario was improved to 5%, meaning only one in twenty mugs is defective. For the use phase, I assumed the owner would be using baking soda instead of dishwashing detergent and would compost the paper packaging. Since my hypothetical owner is very eco-friendly, they also have solar panels to heat the water for dishwashing. As for transportation, the mug was delivered by flight from Europe to the US, the same as in the previous two scenarios. 

How did all these changes influence the carbon balance? For the pre-sale phase, all the measures taken led to a significant 1.2 kg drop in CO₂, from 1.9 kg in an average mug to 0.7 kg in an eco mug. 

The biggest influences were single firing (-0.7 kg), reused packaging (-0.4 kg), elimination of frit (-0.06 kg), and reduced transportation (-0.02 kg). The addition of recycled ceramic shard powder had a minimal effect on the footprint. This was just a 10-gram drop per cup, as it requires electricity to grind the ceramic into powder, not to mention the additional firing testing new materials requires. 

The lifestyle changes of the mug’s owner led to an additional 3.1 kg-CO₂ reduction. Solar-powered water heating resulted in -2 kg, composting led to -0.3 kg, and washing with baking soda led to -0.2 kg CO₂. 

If we compare the dirty and the eco mug scenarios, we’ll see that it is possible to achieve a three-times lower carbon footprint with realistic, relatively easy-to-implement changes. Or even nine times, if we consider just the pre-sale stage, where almost everything is influenced by the potter’s decisions! Isn’t that inspiring? 

Finally, let’s see if it is possible to make a ceramic mug with zero carbon at all. This scenario is theoretical and I went to extremes with assumptions. Nevertheless, this exercise proves that it is conceivable to run a carbon-free ceramic practice, with the help of renewable energy and carbon offsetting. 

What is the Net-Zero Mug? 

Firstly, it is made of local wild clay, with a domestic commercial clay body and recycled-ceramic additions. It is raw glazed with wild clay slip made with rain water, single-fired with electricity produced with roof-top solar panels and stored in a battery, packaged with reused cardboard and paper, and all materials are delivered locally, mostly by train. Such production methods result in a tiny 0.1 kg of CO₂ per cup for the pre-sale stage, where the biggest contribution is from power production. 

After the sale, the cup is shipped from Ukraine to Germany, instead of the US. This is done by train, resulting in 0.02 kg CO₂. It is washed with baking soda and cold water, and its packing materials are composted. 

Altogether, the net-zero mug creates 0.5 kg CO₂ per 350 ml item per full life cycle. While this is an ideal scenario that requires significant changes, I hope you will agree that it isn’t impossible. 

Carbon Offsets 

I stated it would be a net-zero carbon mug, right? So to cut down the last bits of CO₂, we’re going to factor in carbon offsets. 

Carbon offsetting involves paying someone else to remove or compensate for the carbon you emit into the atmosphere. For example, this can be done by investing in renewable energy projects or restoring natural forests. This approach is not without controversy but is still recognized by environmental practitioners. The Gold Standard and the Verified Carbon Standard are the most reliable types of carbon offsets to choose. 

To achieve a net-zero mug, we need to buy 0.5 kg of verified carbon credits. The market price of a carbon credit is between $10–100 per ton of CO₂. Choosing the higher cost credits, it would cost $100 to cover 2000 of these net-zero mugs, or 50 cents per mug. 

I must stress, however, that for the net-zero mug, these Life- Cycle Assessment (LCA) results include only CO₂ emissions. There may be other potential environmental impacts like toxicity or raw materials depletion. 

the author Yuliya Makliuk is an artist and activist based in Ukraine. This article is an excerpt from her book, Potters Save the World: Learn to Make Sustainable Ceramics and Help Protect the Earth. (ISBN-13: 979-8864765364).

1 P. Friedlingstein et al. “Global Carbon Budget 2022.” Earth Syst. Sci. Data 14 (2022): 4811–4900. Published by Copernicus Publications. 

2 Sala S., Crenna E., Secchi M., and Pant R. Global normalisation factors for the Environmental Footprint and Life Cycle Assessment. EUR (28984), Publications Office of the European Union, Luxembourg, 2017. ISBN 978-92-79-77213-9. doi:10.2760/88930. JRC109878.