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The Clay Refrigerator

The Clay Refrigerator

A lidded earthenware pot is fitted inside a larger pot with an insulating layer of sand in between. This sand layer can be kept cool by adding water at regular intervals (generally twice a day), thus providing a refrigerated storage space at minimal cost.

Credit: Practical Action

  • The Clay Refrigerator
  • The Clay Refrigerator
  • The Clay Refrigerator
  • The Clay Refrigerator
  • The Clay Refrigerator

Description

Practical Action is a development charity with a difference. We know the simplest ideas can have the most profound, life-changing effect on poor people across the world. This is why, for over 40 years, we have been working closely with some of the world’s poorest people using simple technology to fight poverty and transform their lives for the better.

Website
http://practicalaction.org/
  • Clay or substitute (eg mud, dung)
  • Water
  • Sand Fire / Kiln

Food preservation is an important issue. Most people living in rural areas and many living in urban areas for that matter cannot afford to buy an electric refrigerator and an alternative method such as the clay refrigerator can act as an appropriate substitute.

The potteries association in Al Fashir made and sold over 50 ceramic refrigerators in 2007 which cost $20 to buy. The ceramic refrigerator has proved very successful and it has been tested with a number of different vegetables. For example tests have shown that these foods can be kept fresh for the following amount of time: 1. Tomatoes – 3 weeks; 2. Bamiah - 2 week; 3. Okra – 2 weeks; 4. Rocket - 5 days.

Download the instruction manual
  • 1
    The first task that needs to be performed is the making of the moulds. To do this make a small hole in the ground and cover it with a mat. Cover the mat with a small amount of wood chippings to prevent sticking. Mix and knead an even mixture of mud, dung and water into a ball. Repeatedly press a stone into the mixture to form a bowl shape. Continue to do this adding more material if necessary until the mould reaches the dimensions given in diagram.
  • 2
    Once the moulds have been made they need to be left to dry in the sun for 30 minutes. Now work can start on making the pots. Once again a small hole is prepared with a coating of wood chippings. The clay is kneaded into a dough like mixture 1. The clay mixture is rolled flat and placed on an upside down mould. The thickness should be 10 mm. Then it is spread over the mould as far down as the moulds widest diameter. Use a flat stone and water to smooth it.
  • 3
    Once the round shape has been formed the walls can be extended to the designated height by removing the mould & adding clumps to the wall. An extra thick layer is then added as a rim which is 20 mm thick. Small pot is complete. The next step is to make the big pot. This process is similar to the making of the small pot with a couple of extra steps. Once the mixture has been spread evenly over the surface of the mould the base is formed using extra mixture by hand.
  • 4
    The walls can now be extended. This is done by removing the mould and adding clumps of the mixture by hand to the wall. An extra thick layer is then added as a rim which is roughly 30 mm thick. The final part of the process is the decoration. This is done by rolling the mixture into a long sausage shape and sticking it around the outside of the pot about two thirds of the way up. Both pots are now left in the sun to dry. This normally takes 4 days in the winter and 2 days in the summer.
  • 5
    The next process is for the pots to be burned. To make this process more efficient it is better to burn as many pots as possible at once. Firstly an area is cleared and a circle is made with rocks. The ground is then covered with cow dung. The clay pots are then piled in the middle and completely covered with sticks and more dung. The fire is then lit and left to burn for 24 hours.
  • 6
    Once the clay pots have been burnt the clay refrigerator can be assembled. Firstly sand should be placed in to the bottom of the large pot forming a layer approximately 5 cm in depth. At this point the small pot should be placed inside the big pot on top of the sand. This should mean that the tops of each pot are now level. Sand can now be put around the outside of the big pot until it is flush with the surface.
  • 7
    Ideally the clay refrigerator should be held in a stand to allow airflow underneath to help with the cooling process. A damp cloth should be placed on top of the inner storage pot to prevent hot air entering.

Some DIY technologies require specialized materials or special training. If your organization is interested in this technology, you are what we call a ‘technology seeker’, and funding for materials or training for this DIY technology may be available through Kopernik.

Technology seekers interested in becoming part of Kopernik can do so by filling out the registration and proposal form downloadable here. Once the registration form is submitted, Kopernik will review the application and conduct due diligence to determine whether the organization meets the requirements of Kopernik. For more information click here.

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