© 2022

The Hidden Beauty Of Sludge




Colour in the circular economy: An interview with colour & material developer Agne Kucerenkaite. Red Dot Award-winning designer, Agne Kucerenkaite, talks to Laura Perryman about colour, provenance and reconceptualising waste.

As the sustainability agenda becomes more urgent, industries are increasingly collaborating with designers to find ways to capture and capitalise on waste before it enters the biosphere.

You can argue that when waste is used, the word loses its meaning. I’m giving a new identity to waste. It’s not a limitation; on the contrary, it encourages me to formulate and experiment creatively.” — Agne Kucerenkaite

Generally, waste is considered to be a material problem. But by seeing colour potential in the most unpromising of places — drinking water treatment sludge — Agne Kucerenkaite has been able to elevate a messy miscellany of minerals into high-value ceramics. Kucerenkaite’s Ignorance is Bliss project challenges the very notion of waste and raises important questions about how we assign meaning and worth in the 21st century.

In this interview, Laura Perryman catches up with Agne to discuss the joys of working with a salvaged palette and the obstacles we will need to overcome if we are to enjoy a healthier relationship with colour, materials and our environment.

Filtration residue from a water processing centre in Lithuania.
Collecting iron-rich sludge from the soil remediation industry for Kucerenkaite’s Ignorance is Bliss ceramic tile collection.

LP It’s nearly two years since we first spoke about your work as a designer and material investigator. I wanted to begin by asking, why did you first choose to work with waste colours?

AK It started with my fascination with raw materials, and that was triggered by a residency in Japan, where I worked for three months with ceramics and porcelain. My project investigated barely remembered materials from the past once used to make colour. Working with Japanese professionals and local people, we would go to sites of specific native minerals. That way, I learnt how to grind, crush and make colour from rock. When I came back from Japan, I wanted to continue, but I felt there needed to be some additional value. I started looking at waste streams because of the huge quantities of raw material. What’s interesting with waste is that you’re not fully in control, and that’s one part I really like: trying to control something that’s not controlled at the beginning.

LP One of the waste streams you’ve investigated, drinking water treatment sludge, contains high levels of iron. Why is this iron residue considered to be waste?

AK  It is quite a valuable material and can be reused, but it is generated in extreme quantities. In Vilnius in Lithuania, the company providing drinking water for half the town generates around 10 tons of iron per month. In the Netherlands, it is the same. Some cities have even several drinking water supply companies, so the quantities are enormous.

Iron extracted from drinking water treatment sludge. Photograph by Darius Petrulaitis.

For me, iron is an infinite number of colours. I have over a thousand glazed ceramic samples, and I don’t have two that are identical.”— Agne Kucerenkaite

As you say, iron is the most abundant metal on earth, and it’s incredibly versatile in hue range, from red, yellow to black and brown. And interestingly, this varies according to the location, provenance and source. Iron is not toxic, and you can also use it as a mordant or fixator for colour in textiles. For me, iron is an infinite number of colours. I have over a thousand glazed ceramic samples, and I don’t have two that are identical. And within ceramics, there is even more to the colour, such as glossiness, transparency and texture.

LP How is the iron extracted?

AK Most of my waste iron comes from Evides, a large water supply company in the Netherlands. It is provided by AquaMinerals, also based in the Netherlands, which looks for and identifies destinations for the material streams that are generated by water treatment processes. They harness water deep from the ground, and with it comes a brown mass of iron, calcium and other minerals they have to remove with specialist methods. One technique, called airing, uses oxygen to bond the iron together, making it drop as matter, as a particle, so you can separate it from the water. All the world does this in a very similar way. It’s the most common way to produce drinking water.

LP What other minerals are in this waste? And what colours do they produce?

AK What’s interesting is that water companies have data from all their locations, so I can also see what is in the sludge. Most of it is iron, but I can see traces or contents of other minerals or pollutants. Through trial and experimentation with firing ceramics, I’ve harnessed these and created a whole palette of distinctive shades.

Each industry has a variety of waste streams they can categorise. Drinking water supply companies in the Netherlands mostly generate iron, calcium carbonate, manganese, carbon, struvite and humic acids. None of those materials is purified, so each will also contain small quantities of other metals, minerals and organic materials. In ceramics, manganese produces violets, browns and blacks. Calcium carbonate is not a colourant but is used in the base glaze to give it hardness and durability. I am testing iron, carbon and humic acids to dye textiles.

Iron colour range on porcelain cups, sourced from drinking water treatment sludge.
Agne Kucerenkaite.

LP How do you work with waste colour?

AK When talking about ceramics, it’s chemistry. You can alter the colour of the iron by using different percentages, playing with the base glaze formulation or varying the temperature or firing method. For example, electric and gas ovens yield different shades.

Everybody knows iron in its natural state, a brown, orange or blackish colour. But it can be yellow, pink, red, purple or green when fired.”— Agne Kucerenkaite

Usually, in ceramics, the base glaze is colourless, and you have to add the pigment separately. Iron is very versatile and has a diversity of colours. Everybody knows iron in its natural state, a brown, orange or blackish colour. But it can be yellow, pink, red, different browns, purples, greens when fired, all depending on how you treat it.

The way iron reacts with other materials and how they bind together reveals the colour variation. You get different results each time, discovering that by changing the firing programme, again you get different shades. My favourite colour is from Ossendrecht in Holland. It’s particularly orange, and I use it a lot. It provides really good results in combination with other minerals. In Vilnius, the earth in the region makes the colour a little different; a yellower shade. You can clearly see that as well when dying textiles. It’s fascinating and will be a project for the coming years.

LP When we spoke a couple of years ago, you had found the toxic colours were the most vibrant. Is this still the case, or have you found other results?

AK From the start, I wanted to avoid using very toxic materials in the glazes. That means achieving a colour range that doesn’t use lead or barium. These are the materials that generally create the best, most vivid, beautiful colours, very nicely melted on the ceramic at usual firing temperatures.

I told myself: I will create a beautiful yellow without using lead.” — Agne Kucerenkaite

Working with a factory, I wanted to look at the whole picture of energy efficiency. We did a test and discovered that firing at a high temperature uses six times more labour and energy. So, we switched to a low firing temperature, which further impacts the colour challenge, as you have to fine-tune more variables. But I told myself: I will create a beautiful yellow without using lead or without high firing temperatures, so basically, that was my goal. My first tests were very promising, and I now have two yellow shades in the tile collection coloured by iron without using hazardous lead or barium.

LP How did you first develop your colours into a product?

AK I work with a professional ceramics workshop called Phoenix Cultuur. It’s one of the best in the Netherlands, with excellent equipment and lots of creative possibilities. Phoenix has supported me by allowing me to work very flexible hours and get professional advice while working continuously to make hundreds of colour samples.

In 2017, I developed tiles for the first time for a family restaurant in Rotterdam. It was so successful that I decided to launch a collection of tiles coloured purely using waste materials. That was three years ago, and I now have a first collection, consisting of twenty colours, produced in a local tile factory. One of my favourite projects has been for a restaurant called Republiek Bloemendaal in Holland, commissioned by a local interior designer, Anne Claus. We selected five colours for the whole range. It was very earthy, very natural.

Agne Kucerenkaite.

I don’t want to lose the craftsmanship within the work, but there needs to be a balance between handmade and industrial processes.” — Agne Kucerenkaite

Working on formulations and colour design is a small part of this project. To make it happen, there are lots of things to learn and to prepare correctly. The tile factory I work with is small, but it can scale up by working with other factories in the same union. They can produce a square metre or a thousand square meters, all made by hand with a lot of attention to each tile. One person selects and cuts the tile, observing it, finishing it. Then the glazing is also mostly done by hand. I don’t want to lose that craftsmanship within the work, but there needs to be a balance between handmade and industrial processes.

LP If a company is interested in working with waste colour, what are the benefits and challenges?

Companies, in general, are not used to exchanging resources, which is why there is such a problem with sustainability in using materials.” — Agne Kucerenkaite

AK For ceramics, the drinking water industry provides a very reliable source as they produce large quantities of waste very frequently, so there would never be a shortage. Of course, there are challenges with how you handle and process this waste. The greater problem perhaps is that companies, in general, are not used to exchanging resources, which is why there is such a problem with sustainability and using materials.

There is so much waste material generated that’s valuable. And people are just starting to see its value.” — Agne Kucerenkaite

Businesses are only just beginning to think about what is leftover and how it can be used. People are working in ways that are time efficient, money efficient and the easiest way to get rid of products. That’s why there is no exchange between businesses and why none of those loops is established. The thing is, it’s a problem now, and we always think the problem will be later. There is so much waste material generated that’s valuable. And people are just starting to see its value. What I am seeing and hoping is that the world is shifting, and I think using waste inventively and safely will happen much more.

LP What other projects are on the horizon?

AK I’ve been considering how I can take colour from waste and recycling further. I am continually investigating applications for other materials, particularly textiles and glass. I’m also working on a project in Amsterdam with a building to be demolished. There will be a plethora of construction waste which I’ve suggested goes directly into the body of the clay. On top of that, we may use the waste from Amsterdam water processing to create a colour only used for this project. A bespoke local waste shade. I’d like to collaborate with other companies using diverse waste materials we can integrate in the future.

‘Ignorance is Bliss’ glass samples coloured with industrial metal waste.
Sludge-derived iron used to dye a linen rug sample.
Yarns for hand-woven textiles dyed with sludge-derived iron by Kucerenkaite.

Agne doing colour research for Ignorance is Bliss. Photograph by Nicole Marnati. Copyright DAE.

Lutetia carpet with orange tones derived from iron waste. Photograph by Darius Petrulaitis.

LP That’s so nuanced to the locality. Is this a developing trend?

AK What I see is that people are taking more time with storytelling. People ask ‘why are we doing this?’ and carefully choosing materials to align with the intended narrative. What I’ve found is that people are always building houses and changing interiors. Still, I’ve noticed a growing appreciation for mindful or ethical materials that use waste.

LP One final question: what is a waste colour to you?

AK You can argue that when waste is used, the word loses its meaning. I’m giving a new identity to waste. It’s not a limitation; on the contrary, it encourages me to formulate and experiment creatively.

Increased landfill restrictions and environmental concerns are forcing water treatment plants to search for new, alternative uses for colour-rich sludge, but the picture is far from consistent globally. In Japan 55% of iron-rich sludge is reused; in the USA, 35%; while in Poland the figure is just 2%.

Not to be confused with wastewater sludge, drinking water treatment sludge, or DWTS is classed as non-hazardous. However, it is well documented that discharging this metal-rich material into the environment is harmful.

Sustainability hasn’t always been an integral component of design education. But a generation of designers like Kucerenkaite, who question wasteful processes, is shaping the debate, asking how we can avoid waste and how existing waste can be reincorporated and redefined. When designers are knowledgeable about colour provenance, they can initiate conversations with clients, manufacturers and consumers that enable us all to make informed choices that are better for the planet.

The success of projects that harness colour to close waste loops will ultimately depend on the colours themselves. Waste colour will never give the same results as a chemically controlled pigment due to its more complex composition; every time it is deployed, it will produce a subtly, or not so subtly, different shade. As Kucerenkaite notes in her interview, not one of her samples is the same. So the question is, are industries and individuals accustomed to colour precision ready to embrace a new aesthetic of colour caprice?

The future is… vibrant, fluctuating, dappled, surprising, flowing, grainy, uneven, shaded, soft, liquid, marbled, mineral, textured, rich, vivid, intermixed, uneven, rich, earthy, raw, textured, gradient, earthy, diverse, organic, speckled, richly, varied, nuanced, sensitive, plentiful.

Many thanks to Agne Kucerenkaite for taking part in Circular Colour.Circular Colour is a series of interviews, essays and colour profiles in which we explore approaches to colour that could significantly change the way we tackle waste.

This piece was originally published in Radical Colour on Medium.



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