Ceramic liner in a ‘cob’ stove

Holey Roket cooking stove can be reinforced with a cob earth mixture (composed of clay, sand and plant fibres, like straw). The cob can be shaped by putting it in a mold, like shown below.

Cob mixture is a very strong and durable material when dried. It is used in traditional architecture in many countries where modern building materials are not available.


  1. clay – 2.5kg
  2. sand (up to 1 cm)- 1kg
  3. plant fibres (up to 3 cm) – 0.3kg
  4. water – 1,25L

Materials need to be evenly mixed, best with stomping on it with barefoot. The texture needs to be just right, not too wet and not too dry.


Cermic liner is made same way as a Holey Roket stove, using app. 1/3 clay and 2/3 sawdust, depending on the clay quality. It is fired to approximately 900 degrees celsius.

We made 2 straight pieces with 45 degree cut and assembled it straight in the mold.


First you need a mold or formwork, which can be wooden or metal. You apply the mixture to the mold, while inserting the ceramic liner inside on the right height.

The surface of the cob stove can be polished or covered with a lime or other kind of plaster to protect it from the weather.

The project of building a cob stove is part of the BIO27 Bienalle of design in Ljubljana https://27.bio.si/

2 thoughts on “Ceramic liner in a ‘cob’ stove

  1. This is great to see. I had a similar idea in Ethiopia and indeed was 50% of my Graduate Thesis. Utilize local materials and techniques for improved rocket stoves that burn biomass briquettes. I designed a way to repeatedly produce standardized stoves that can utilize biomass briquettes, both of which could sustain small businesses. I learned a lot and am glad to see the work continues.

  2. Dear Brian, I’m happy to hear from you; do you have any photos or thesis to share? You ca n send it to my email rok.stoves()gmail.com

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