How to Craft the Ultimate Eco-Friendly Mug

The year 2023 is poised to become the hottest in human history.^[1] It's time for ceramic artists to do their part and respond to the climate crisis. But what exactly can we do?

On the one hand, as our world hurtles toward an uncertain future, the idea of extracting non-renewable mineral resources and emitting tons of CO2 solely to create a humble pot is increasingly difficult to justify. On the other hand, the resources we rely on, including energy, water, clay, and other vital minerals, are at risk of becoming too scarce and expensive commodities for a potter to use.

Caring for our planet isn't just a noble cause; it's a responsibility that touches every facet of our lives, even our beloved craft of pottery. Many artists working with clay start questioning their practice and how (and if) they can continue it in the age of the Anthropocene.

In this article, I will focus on the basic steps to address this challenge based on my research. 

As an environmentalist and self-taught potter, questions about the potential harm to nature swirled in my mind as I started my journey into ceramics, with dreams of running an environmentally-conscious studio. I decided to calculate the carbon footprint of a handmade ceramic mug and model different scenarios to find the ultimate eco-friendly way of making a mug. I hoped that this method would allow me to gain insight into what makes ceramics more or less sustainable and how to create the greenest pottery possible. 

Insights from this journey laid the groundwork for my upcoming book, Potters Save the World: Learn to Make Sustainable Pottery and Help Protect the Earth. Here, I offer a condensed version of some of its chapters.

Decoding the Carbon Footprint

An environmental footprint is a measure of how much a product or process impacts nature. Scientists use quantitative data, such as raw material consumption and pollution emissions, to evaluate the impacts of various items, from cars to cities.

In 2023, humanity's collective environmental footprint, measured in hectares of land, equals a staggering 1.7 Earths.^[2] This alarming statistic reflects our consumption – nearly twice what the Earth can sustainably provide in the long run.

When measured in CO2 emissions, it is called the carbon footprint. Understanding an object's carbon footprint allows us to compare different products and make better choices for the environment as customers and as designers.

Estimating the Carbon Footprint of a Handmade Ceramic Mug

I wanted to estimate the carbon footprint of a typical handmade ceramic mug. But what do I mean by "typical"? 

It is an average model of a mug you might encounter at craft fairs or on social media – a basic handmade drinkware without specific sustainability measures. 

Imagine a 350 ml (12 oz) mug crafted from local stoneware clay, shaped on a traditional kick wheel, and coated with a standard commercial glaze. It undergoes two rounds of firing in a kiln powered by regular grid electricity, reaching temperatures of cone six (1200°C). It tips the scales at 350 g upon completion, with every tenth mug discarded due to defects. The mug then gets packaged in plastic bubble wrap and a cardboard box and shipped to its new owner from Europe to the USA via airplane. Over three years, it gets used every third day, undergoes hand washing with dishwashing detergent, and eventually finds its resting place in a landfill, along with its packaging.

My analysis covered every phase of the mug's life cycle:

1. Extraction of raw materials for clay, glaze, and packaging.
2. Domestic transportation of clay, glaze, and packaging to the studio.
3. Mug production in the studio (including throwing, bisque firing, glazing, and glaze firing).
4. Packaging (both plastic and cardboard).
5. International shipping (by plane).
6. Use by the owner (handwashing).
7. Disposal (landfill or recycling).

I collected data on material usage at each stage, drawing insights from my own studio experience and existing literature. To convert these measurements into CO2 emissions, I used Mobius Ecochain software and data from the Ecoinvent v3.8 Cut-Off database, a repository of global environmental impacts.

Revealing the Carbon Footprint

The carbon footprint, from inception to disposal, of an "average" handmade mug stood at 7.5 kg of CO2. To put it in context, this accounts for 0.1% of an individual's annual carbon footprint.^[3]

Interestingly, the stages leading up to the mug's sale made up a smaller portion of this footprint, totaling 1.9 kg of CO2. This includes raw materials, domestic transportation, production, and packaging – everything before the mug reaches its owner. Notably, the most carbon-intensive points in this phase include firing (1.4 kg), plastic packaging (0.3 kg), cardboard boxing (0.07 kg), frit production (0.06 kg), domestic material transportation (0.06 kg), and clay extraction (0.04 kg).

Additional factors like water usage accounted for less than 1% of the total footprint.

As we move beyond the studio stages, the environmental impact continues to unfold. Key contributors include cargo flight from Europe to the USA (2.6 kg), the energy required to heat water for dishwashing (2.2 kg), dishwashing detergent production (0.4 kg), and the eventual decomposition of packaging materials in landfills (0.3 kg).

This corresponds well with published studies of the carbon footprint of handmade ceramics that suggest a range of 0.7 to 3.1 kg of CO2 per item (only in-studio stages).^{[4][5][6][7][8]} A staggering 80% of this footprint is linked to kiln firing, whether powered by fossil fuels or electricity.

Now, what do we do with these numbers? We can use them as a benchmark for studio pottery production: approximately 2 kg of CO2 per mug before it leaves the studio and 7.5 kg CO2 per mug for a full life cycle. 

The exciting news is that we possess the power to shrink – or inflate – a mug's carbon footprint by up to threefold through our daily choices in a potter's practice and a client's lifestyle. Key factors at play include firing methods, material choices, shipping distances and modes, packaging materials, and the preferences of the mug's owner for washing and disposal.

Let's take a closer look at how small changes can make a big difference in the environmental impact of the mugs we create.

The "Dirty" Mug Scenario

In a less environmentally friendly version of the handmade mug, the carbon footprint jumped by a whopping 60%, going from 7.5 to 12 kg of CO2 per cup. This mug was made with choices that were less green:

- Imported clay and frit (+0.1 kg CO2): Transporting the materials from far away resulted in burning fuel and emission more CO2.

- Glaze colored with cobalt oxide (+0.1 kg): Adding cobalt oxide for color made it less eco-friendly.

- Liquid gold for decoration (+2.2 kg CO2): Using liquid gold for decoration really bumped up the emissions.

- Fired three times with coal-based electricity (+1.5 kg CO2): Multiple firings with coal-based electricity used a lot more energy and increased emissions.

- Packaging in a box with polystyrene, which was incinerated after use (+0.5 kg CO2): Polystyrene has a bigger carbon footprint than polyethylene bubble wrap.

- A 20% discard rate (+10% to resulting emissions per mug): More mugs being thrown away, with one in five being defective, made things worse for the environment.

Running these calculations shows that these particular practices contribute to greater harm to nature and should be avoided where possible.

The "Eco-Friendly" Mug Scenario

On the other side, a more eco-friendly version of the mug showed a remarkable 45% drop in the overall carbon footprint compared to the "average" mug, bringing it down to 4.1 kg of CO2. In this scenario, eco-conscious choices were made:

- Single firing (-0.7 kg): Skipping the bisque firing step used less energy and reduced emissions.

- Reused paper packaging (-0.4 kg): Opting for reused cardboard boxes and paper cushioning cuts down on waste and emissions.

- Changes in the mug owner's habits (-3.1 kg): Solar-powered water heating (-2 kg) and washing with baking soda (-0.1 kg).

 - Composting paper packaging (-0.3 kg): It is much better than landfilling or incinerating it. 

These are some of the choices that a potter can make in order to make her or his ceramic practice more sustainable. 

Comparing the "dirty" and "eco" mug scenarios shows that we can make a big difference for the environment by making simple, realistic changes in our practice. 

Further modeling has shown that, in theory, it is possible to create a mug with a carbon footprint close to zero. To do this, we need to start with the "eco" mug practice but use electricity from roof-top solar panels for firing, limit our sales to one continent, and ship only by train. This way, the mug's footprint would be about a mere 0.5 kg CO2, which could be additionally offset by planting trees or purchasing carbon credits. 

Now, let's break down this knowledge into practical steps that virtually any ceramicist can do to lower his or her carbon footprint. 

Smart and Green Firing

As discussed earlier, the kiln is responsible for about 80% of a conventional bisque-to-glaze pottery production carbon emissions. How do we cut that number?

Here are some quick and cost-effective tips to tread lightly when firing:

- Quality Control: Implement rigorous quality control measures before firing, reducing the need for refiring or discarding the pots.

- Avoid Idle Firing: Avoid firing kilns when they are partially empty. Opt for tight firing to maximize energy efficiency.

- Faster Firing Ramps: Select firing schedules that consume less energy by eliminating unnecessary pre-heats, holds, and slow temperature rises.

- Proper Kiln Insulation: Ensure your kiln is adequately insulated and the lid and peepholes close tightly to retain heat efficiently.

- Low-Firing Materials: Where possible, opt for materials that require lower firing temperatures, reducing energy consumption. 

- Single Firing: By glazing items when they are leather hard or bone dry and employing a slower glaze cycle, you can save time and money and reduce carbon emissions by skipping the bisque firing step.

- Smokeless Firing with Wood Waste: While calculating the carbon footprint of wood-firing remains complex due to varying opinions on whether wood is carbon-neutral, sustainable wood harvesting, smokeless firing, and shorter firing cycles can make wood-firing a reasonably "green" option.

- Choosing a Greener Fuel Type: Make an informed decision based on the carbon emissions of different fuels. See the table below.

 Approximate carbon intensity of fuels in different kiln types. 

Type of kiln fuel	CO2 emissions per firing an average mug, kg
Wood, dead branches in portable "vegan" kiln (Dr. Steve Harrison, interview for Potters Save the World book, estimated by me)	0.2, excl. bisque firing
Roof-top solar (from Potters Save the World)	0.3
Wood in two-chamber noborigama with waste vegetable oil one day (John Britt cited by Denise Joyal)[9]	0.4, excl. bisque firing
Propane (estimated by me)	0.6
Ukraine grid mix (from Potters Save the World)	1.2
Coal-based electricity (from Potters Save the World)	1.7
Wood in anagama three days (Gudenky art residence, estimated by me)	2.6, excl. bisque firing
Wood in anagama eight and a half days (Kristin Muller cited by Denise Joyal)	5, excl. bisque firing

Conscious Material Choices

Primary raw materials in ceramics are non-renewable, demanding judicious use. These materials, originating from the Earth, include clay, feldspars, kaolin, and silica, while metal oxides provide color. 

While clay and most pottery minerals are generally abundant, certain specific grades could become depleted. Certain materials have considerable environmental and social ramifications, making them best avoided.

Here are some guiding rules for the sustainable use of raw materials:

1. Avoid Troublesome Metals: Extracting metals like cobalt, copper, and gold often causes problems for the environment and communities. It's better to steer clear of them.
2. Smart Shopping for Earth-Friendly Materials: When you're buying materials for your ceramics, be a mindful shopper. Always check with the supplier where your ceramic supplies come from. Give top priority to those that are sourced locally and produced ethically.
3. Get Hands-On with Clay and Minerals: It's a great idea to gather your own clay and minerals for your ceramics. Just remember to follow the rules and guidelines to avoid any legal issues or harm to the land.
4. Recycle and Reuse: Instead of digging up new raw materials, you can use waste materials from other industries like glass, rocks, and even eggshells in place of the primary stuff. 

Repurposing Waste for a Greener Future

Pottery studios generate a fair share of waste, from clay reclaims to broken pots, mixed glaze sludge, toxic oxides, and discarded packaging materials. While dealing with these can be challenging, it also offers an opportunity for creativity and resourcefulness.

The 5R hierarchy stands as a compass for waste management: Refuse, Reduce, Reuse, Repurpose, Recycle. Identify the types of waste generated in your practice and manage them according to these rules.

- Unfired Clay: Continuously reclaim and reuse unfired clay, minimizing waste generation.

- Glaze Remnants: Gather and repurpose glaze remnants to create new glazes or glaze granules, ensuring every bit gets a second life. Never discard glaze waste in the sink or outdoors. 

- Fired Ceramics: Crush and grind fired ceramics, transforming them into grog or ceramic powder to add to the casting slip. It helps to replace raw materials, extending their usefulness. 

Environmental Consciousness in Packaging

Ceramics are delicate, demanding careful packaging to prevent breakage. Yet, the environmental consequences of excessive packaging and waste in landfills cannot be overlooked. The most straightforward and effective approach to reducing the environmental impact of packaging is to reuse boxes and wrapping materials.

A preliminary examination of popular packaging materials for ceramics, ranked from the most environmentally friendly to the least, yields the following insights:

1. Reused Paper and Cardboard: The greenest option, as it is biodegradable and promotes the circular use of resources while minimizing waste.
2. Starch-Based Peanuts and Films: A biodegradable alternative that reduces environmental harm compared to traditional plastic packing materials.
3. New Paper and Cardboard: While not as sustainable as reused or recycled materials, new paper and cardboard are still preferable to many other options.
4. Polyethylene Films and Bubble Wrap: A less eco-friendly choice, as it relies on petroleum-based materials and produces microplastics, contributing to environmental concerns.
5. Styrofoam: Among the least sustainable options, polystyrene has significant negative environmental implications due to its non-biodegradable nature.

Beyond the Mug Making

From ceramic travel mugs designed to substitute for single-use coffee cups to innovative creations like artificial ceramic coral reefs, artists and crafters are at the forefront of sustainable changes. Their efforts instill optimism about the future of studio ceramics, where the potential extends beyond creating beautiful pieces to becoming leaders in product design, sustainability education, and green business practices.

Besides making ceramics with a smaller carbon footprint, we can also make them bring about positive changes in society. Here's a quick guide:

1. Design for a Greener Life: Craft ceramic items that make it easier for people to live in an eco-friendly way. Like travel mugs, ceramic water filters, and rocket stoves for cooking.
2. Art with a Message: Use your ceramics to share powerful environmental messages, turning them into a canvas for change. Think pictures of endangered species, environmental slogans, or art that reflects on the state of the planet. 
3. Art that Gives Back: Raise funds for organizations protecting nature through your art. Every piece can make a difference.
4. Join Forces with Scientists: Collaborate with scientists to use clay and ceramics to restore our natural world. Examples include artificial coral reefs, insect hotels, and other habitats. 
5. Create Experiences: Explore new realms of art with installation and performance to give your audience a cathartic connection with nature.
6. Unleash Your Creativity: Find your unique way of using your talents to tackle environmental challenges because creativity knows no bounds.
7. Team Up and Share: Work together, co-create, communicate your ideas, and, most importantly, enjoy the journey! Use hashtags like #PottersSaveTheWorld and #SustainableCeramicsPractice on social media to find like-minded artists. 

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The Book for Sustainable Ceramicists

If you're keen to dive deeper into eco-friendly practices and want to learn directly from some of the best sustainable potters on Earth, I hope you will check out my new book, Potters Save the World: Learn to Make Sustainable Pottery and Help Protect the Earth. 

Based on the carbon footprint assessment and featuring personal stories from Dr. Steven Harrison, Sara Howard, Caroline Cheng, Joe Thompson, Courtney Mattison, and many more, the book offers evidence-based advice on topics like:

• Firing Ceramics Sustainably;
• Eco-Friendly Ceramic Materials; 
• Zero Waste Studio Practice; 
• Managing a Sustainable Ceramic Business; 
• and Positive Impact Beyond Pottery Studio. 

This book caters to both novices and seasoned ceramicists, answering pressing questions such as: How to reduce energy consumption during firing; Is wood firing sustainable; How to recycle flawed ceramics; and How pottery can preserve ecosystems and stop war.

It is scheduled for release at the beginning of November 2023 as a self-published edition, available in paperback and e-book formats on Amazon.com and Etsy.com. 

Use coupon STUDIOPOTTER10 to get a 10% discount on Etsy. 

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NOTES

^[1] Zeke Hausfather. “State of the climate: 2023 now likely hottest year on record after extreme summer,” The Carbon Brief (July 2023), https://www.carbonbrief.org/state-of-the-climate-2023-now-likely-hottest-year-on-record-after-extreme-summer/.

^[2] "This year’s Earth Overshoot Day lands on August 2: The trend is flattening but still far from reversing," Earth Overshoot Day (July 24, 2023), https://www.overshootday.org/newsroom/press-release-june-2023-english/.

^[3] Sala S., Crenna E., Secchi M., Pant, R., "Global normalisation factors for the Environmental Footprint and Life Cycle Assessment," Publications Office of the European Union, Luxembourg (2017).

^[4] Železný A, Kulhánek J, Pešta J, Kočí V. "LCA Case Study of Ceramic Tableware: Ecodesign Aspects of Ceramics Production from Ancient Technology to Present Factory," Sustainability (2023): 9097. 

^[5] Paula Quinteiro, António Araújo, Bruna Oliveira, Ana Cláudia Dias, Luís Arroja. "The carbon footprint and energy consumption of a commercially produced earthenware ceramic piece," Journal of the European Ceramic Society Volume 32, Issue 10 (August 2012): 2087-2094.

^[6] Li Y, Sharaai AH, Ma S, Wafa W, He Z, Ghani LA, "Quantification of Carbon Emission and Solid Waste from Pottery Production by Using Life-Cycle Assessment (LCA) Method in Yunnan, China," Processes (May 2022): 926.

^[7] Phairat Usubharatana and Harnpon Phungrassami, "Effect of functional unit and processing types on carbon footprint and specific energy consumption assessment of Thailand tableware products," International Journal of Sustainable Engineering (2021): 460-470.

^[8] Pham Phu, Song Toan & Thi, Hoa. "Carbon Footprint Evaluation for the Traditional Pottery Village - A Case Study in Hoi An City, Vietnam," Chemical Engineering Transactions (2020): 78. 

^[9] Denise Joyal, "Aesthetics and Environment, Kilns and Carbon," Ceramics Monthly (February 2011). https://ceramicartsnetwork.org/docs/default-source/uploadedfiles/wp-content/uploads/sites/6/2017/02/048-053-feb11-cm-1.pdf