Clay, Iron sludge

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Circular 217 Glaze 16 Pigment 49 Recycled 123 Clay 17 Glaze 2

Clay, Iron sludge

Photos: Kirstie van Noort, Britt Roelse

From sludge to tile

In this project, designers Kirstie van Noort and Lotte de Raadt developed new ideas for the use of iron sludge in ceramics and tiles. Iron sludge is a residual waste product from water production in the Netherlands.

Having a deep red colour, they quickly realised the sludge could potentially be a great source for making ceramic pigments. Kirstie and Lotte tested several applications and found that the material can indeed be used to produce a beautiful pink/red colouring on ceramics. They ended up developing a line of wall tiles in different shades that can be used in sustainable architecture.

The first tiles will be applied in a new groundwater production plant of Brabant Water, which is currently designed by the Architecture firm Inbo. More than a thousand litres of local iron sludge will be processed to produce 10.000 tiles for a prominent wall in this building.

The tiles will be applied in an artistic pattern reflecting the character of water. 
At this moment ceramics company Koninklijke Tichelaar is taking care of the production of the tiles. The realisation of the water production plant is planned for 2023.

Additional information

The tiles are coloured with a natural and local pigment called iron sludge, which was collected at the water extraction plant in Eindhoven. There, groundwater is pumped up and processed into drinking water.
Groundwater is located in wells hundreds of meters deep below the surface and contains many minerals, including iron sludge.
There is currently no application for the iron sludge at the production site in Eindhoven, so this water containing iron oxide is regarded as waste and is flushed back to the sewer. Kirstie and Lotte drain this turbid water from the so-called buffer pond of the water production company to use in our products. The iron sludge is processed into pigment in their own workshop. First, it is filtered and dried again. This creates chunks that are ground and sieved into a rusty powder. This pigment is mixed into clay in different proportions to obtain different colours.

Information submitted by the maker and edited by the Future Materials Bank.


Stoneware clay, iron sludge, transparent glaze.