Inspired by waste seen in other aspects of her life and the work of designers and artists focused on sustainability, Claire Ellis has made use of the sediment, seconds, and waste common in ceramics studios.
I work in Wurundjeri Woi-wurrung Country in Melbourne. In Australia, First Peoples have maintained deep relationships with land, materials, and ecosystems for over 65,000 years. The impacts of colonization, including displacement, loss of cultural authority, and policies such as the Stolen Generations, coincided with irreversible ecological damage across Australia. When I think about sustainability and circularity in ceramics, I’m reminded that caring for resources, avoiding waste, and taking only what is needed are long-standing principles in many Indigenous knowledge systems.
Today, we live in a global environmental crisis driven largely by industrialized extraction and production. While ceramic practice is not a major contributor, it still raises an important question: What are we responsible for? Ceramics has always been a medium for reflection and cultural dialogue. If we approached our materials with the mindset of custodianship rather than ownership—treating them as resources we care for rather than commodities we consume—how might that shift our practices? What responsibilities do we carry toward the materials we use and transform? Would we still discard them as custodians?
Impetus for the Research
My concern with waste began during my years as a chef; different kitchens produced vastly different amounts of waste, reflecting the priorities of the executive chef. Later, as a ceramic studio technician, I emptied sink traps and filled garbage bins with fired ceramics. Throwing away materials that felt precious—knowing the labor, energy, and emissions embedded in them—made waste impossible to ignore and showed me the resource quantities.
Designer Sarah K’s “Earth The New Client” teaching, which prioritizes sustainability within design, also shaped my early ceramics practice and still guides me. “What needs to be used?” guided my experimentation, especially as I learned more about mining’s impacts. Research with Clay Matters, a collective of Australian ceramicists dedicated to implementing environmentally friendly practices in their studios, on material provenance also revealed how hard it is to trace sources through long supply chains, access specific data, and make informed decisions.
All this led me toward a clear direction: to substitute virgin materials with local second-life resources wherever possible. This approach is part practical, part political, and part personal. Focusing on material reuse is a helpful outlet for my climate distress, and in small ways, contributes to a sense of agency. The experimentation involved keeps me excited in the studio.
Material Custodianship: The Philosophy
While working with like-minded friends on Bulk Buy, a pop-up shop selling recycled materials for ceramic artists, the philosophy of material custodianship came into my awareness. We adapted a transfer-of-custody agreement from Revival Projects, outlining principles of responsible use and a duty of care for customers.
“Look after the land and the land will look after you,” an Indigenous Australian proverb highlighting reciprocity between humans and nature. Custodianship in ceramics might begin with understanding that materials are part of the Country (land, waters, and all beings).
Applied to ceramics, custodianship could mean considering the origins and limits of clay, minerals, water, and fuel; prioritizing second-life resources; and passing on knowledge so future handlers can continue to care for materials.
The Studio Waste Streams I Focus On
a. Sink-Trap Waste
Sink sludge accumulates in most shared studios, containing clays, glaze residues, sponge fragments, hair, and other debris. As it compresses, it forms unique layers like studio-made sedimentary rock.
Despite its mineral-rich potential and its long history of extraction, processing and global transportation, variability, and smell mean thousands of kilos of it are sent to landfill annually.
b. Fired Seconds
Cracked, warped, flawed, or uncollected student work forms the largest ceramic studio waste stream. Some can be prevented or repaired, but seconds will never disappear. Fired ceramics don’t decompose, and crushing them for reuse is rare, partly due to limited equipment and knowledge.
Transforming Ceramic Waste Into New Materials
a. Sink-Trap Material Clay Bodies and Glazes
Sink sludge is often low in plasticity, but it suits press-molding where its beautiful layers and marbling can also be preserved. Its high flux content means it vitrifies at lower temperatures for energy efficiency. I’ve used it for single-fired unglazed artwork and designs, and have had unique results from experimental techniques like stacking and carving or tearing and pinching slabs, as well as piping. When dried, crushed, sifted, and mixed with fresh clay, sludge becomes even more versatile. I’ve used up to 20% when handbuilding, throwing, and slip-casting. Testing across firing ranges reveals color options and prevents slumping and bloating.
Reliable starting points are substituting it for the clay source in a glaze recipe or making a triaxial test, blending it with a glass former and flux. My MOTHEROCK decanters are glazed using 20% sludge, recycled glass, and rock by-products.
Studios with glaze-mixing rooms or spray booths produce sink-trap material that can become an easy, but rewarding, 100% recycled sludge glaze. After sifting, testing across firing ranges produces generous color and texture results suitable for sculptural work. In general, I’ve found mattes at earthenware temperatures, satins at mid-fire, and gloss at stoneware.
b. Fired Seconds Aggregate, Grog, Clays, and Glazes
To recycle fired seconds, I break them with a block splitter, crush them using a rock crusher, and sift the ground bisque into mesh sizes, each suited to different methods. Fine powder becomes a stabilizer in glazes and can balance overplastic clay.
Grog from bisque-fired seconds majorly increases recycled content with minimal aesthetic impact. Crushed-glazed seconds can produce subtle speckles or be muted under glaze. Coarser pieces create terrazzo-like effects in sanded press-molded work.
This material creates a regenerative loop where ceramics feed back into themselves, evolving like a master stock. Caroline Cheng is a leader in this area, with her studio producing tiles and bricks made entirely from crushed seconds.
Implications and Vision Moving Forward
Studio waste streams carry material, environmental, and social value. With landfill space shrinking, using what already exists reduces land pressure, emissions, the heavy waste footprint of virgin materials, and creates possibilities.
It’s challenging, but shared equipment, larger-scale processing, and more education and funding could make it more viable. My in-person and online workshops on material reuse aim to support this shift.
Momentum will grow if we treat custodianship as a collective responsibility. As Jane Goodall reminds us, “Every individual matters.” What if we saw every material as something worth caring for?
the author Claire Ellis is a Canadian-born ceramic artist and designer based in Naarm (Melbourne), Australia. She won the innovation award at the 2022 Warrandyte Pottery Expo and was a finalist in The Churchie Emerging Art Prize in 2024. Ellis is passionate about climate justice, and aims to create opportunities for catharsis and political change through her work.
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Inspired by waste seen in other aspects of her life and the work of designers and artists focused on sustainability, Claire Ellis has made use of the sediment, seconds, and waste common in ceramics studios.
I work in Wurundjeri Woi-wurrung Country in Melbourne. In Australia, First Peoples have maintained deep relationships with land, materials, and ecosystems for over 65,000 years. The impacts of colonization, including displacement, loss of cultural authority, and policies such as the Stolen Generations, coincided with irreversible ecological damage across Australia. When I think about sustainability and circularity in ceramics, I’m reminded that caring for resources, avoiding waste, and taking only what is needed are long-standing principles in many Indigenous knowledge systems.
Today, we live in a global environmental crisis driven largely by industrialized extraction and production. While ceramic practice is not a major contributor, it still raises an important question: What are we responsible for? Ceramics has always been a medium for reflection and cultural dialogue. If we approached our materials with the mindset of custodianship rather than ownership—treating them as resources we care for rather than commodities we consume—how might that shift our practices? What responsibilities do we carry toward the materials we use and transform? Would we still discard them as custodians?
Impetus for the Research
My concern with waste began during my years as a chef; different kitchens produced vastly different amounts of waste, reflecting the priorities of the executive chef. Later, as a ceramic studio technician, I emptied sink traps and filled garbage bins with fired ceramics. Throwing away materials that felt precious—knowing the labor, energy, and emissions embedded in them—made waste impossible to ignore and showed me the resource quantities.
Designer Sarah K’s “Earth The New Client” teaching, which prioritizes sustainability within design, also shaped my early ceramics practice and still guides me. “What needs to be used?” guided my experimentation, especially as I learned more about mining’s impacts. Research with Clay Matters, a collective of Australian ceramicists dedicated to implementing environmentally friendly practices in their studios, on material provenance also revealed how hard it is to trace sources through long supply chains, access specific data, and make informed decisions.
All this led me toward a clear direction: to substitute virgin materials with local second-life resources wherever possible. This approach is part practical, part political, and part personal. Focusing on material reuse is a helpful outlet for my climate distress, and in small ways, contributes to a sense of agency. The experimentation involved keeps me excited in the studio.
Material Custodianship: The Philosophy
While working with like-minded friends on Bulk Buy, a pop-up shop selling recycled materials for ceramic artists, the philosophy of material custodianship came into my awareness. We adapted a transfer-of-custody agreement from Revival Projects, outlining principles of responsible use and a duty of care for customers.
“Look after the land and the land will look after you,” an Indigenous Australian proverb highlighting reciprocity between humans and nature. Custodianship in ceramics might begin with understanding that materials are part of the Country (land, waters, and all beings).
Applied to ceramics, custodianship could mean considering the origins and limits of clay, minerals, water, and fuel; prioritizing second-life resources; and passing on knowledge so future handlers can continue to care for materials.
The Studio Waste Streams I Focus On
a. Sink-Trap Waste
Sink sludge accumulates in most shared studios, containing clays, glaze residues, sponge fragments, hair, and other debris. As it compresses, it forms unique layers like studio-made sedimentary rock.
Despite its mineral-rich potential and its long history of extraction, processing and global transportation, variability, and smell mean thousands of kilos of it are sent to landfill annually.
b. Fired Seconds
Cracked, warped, flawed, or uncollected student work forms the largest ceramic studio waste stream. Some can be prevented or repaired, but seconds will never disappear. Fired ceramics don’t decompose, and crushing them for reuse is rare, partly due to limited equipment and knowledge.
Transforming Ceramic Waste Into New Materials
a. Sink-Trap Material Clay Bodies and Glazes
Sink sludge is often low in plasticity, but it suits press-molding where its beautiful layers and marbling can also be preserved. Its high flux content means it vitrifies at lower temperatures for energy efficiency. I’ve used it for single-fired unglazed artwork and designs, and have had unique results from experimental techniques like stacking and carving or tearing and pinching slabs, as well as piping. When dried, crushed, sifted, and mixed with fresh clay, sludge becomes even more versatile. I’ve used up to 20% when handbuilding, throwing, and slip-casting. Testing across firing ranges reveals color options and prevents slumping and bloating.
Reliable starting points are substituting it for the clay source in a glaze recipe or making a triaxial test, blending it with a glass former and flux. My MOTHEROCK decanters are glazed using 20% sludge, recycled glass, and rock by-products.
Studios with glaze-mixing rooms or spray booths produce sink-trap material that can become an easy, but rewarding, 100% recycled sludge glaze. After sifting, testing across firing ranges produces generous color and texture results suitable for sculptural work. In general, I’ve found mattes at earthenware temperatures, satins at mid-fire, and gloss at stoneware.
b. Fired Seconds Aggregate, Grog, Clays, and Glazes
To recycle fired seconds, I break them with a block splitter, crush them using a rock crusher, and sift the ground bisque into mesh sizes, each suited to different methods. Fine powder becomes a stabilizer in glazes and can balance overplastic clay.
Grog from bisque-fired seconds majorly increases recycled content with minimal aesthetic impact. Crushed-glazed seconds can produce subtle speckles or be muted under glaze. Coarser pieces create terrazzo-like effects in sanded press-molded work.
This material creates a regenerative loop where ceramics feed back into themselves, evolving like a master stock. Caroline Cheng is a leader in this area, with her studio producing tiles and bricks made entirely from crushed seconds.
Implications and Vision Moving Forward
Studio waste streams carry material, environmental, and social value. With landfill space shrinking, using what already exists reduces land pressure, emissions, the heavy waste footprint of virgin materials, and creates possibilities.
It’s challenging, but shared equipment, larger-scale processing, and more education and funding could make it more viable. My in-person and online workshops on material reuse aim to support this shift.
Momentum will grow if we treat custodianship as a collective responsibility. As Jane Goodall reminds us, “Every individual matters.” What if we saw every material as something worth caring for?
the author Claire Ellis is a Canadian-born ceramic artist and designer based in Naarm (Melbourne), Australia. She won the innovation award at the 2022 Warrandyte Pottery Expo and was a finalist in The Churchie Emerging Art Prize in 2024. Ellis is passionate about climate justice, and aims to create opportunities for catharsis and political change through her work.
To learn more about Ellis and her work, visit claireellisceramics.com or follow her on Instagram @claireellisceramics.
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