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Materials for Mud Stoves from "Women and Energy" - Extracted by Viv Abbott
As you have to use the materials from around and the soil quality often changes from one place to the other, there are no strict rules which materials to use in which proportions. But there are some helpful and important guidelines on how to get a strong, non-cracking material mix. Before you start collecting building materials, carefully investigate what is available in the area and far surroundings. It is worthwile to take your time and even bring materials from far, if they help to make a good building mix. Clay from termite hills, is ideal, also look for soil that was dug out from deep down (latrine, well, garbage pit). It is often there that you find what you need: 'Murram', or clay, soil or sand. Look for 'Murram' with as many stones in it as possible. This is an excellent stove-building material. Murram is a mixture of clays and gravel commonly found in Kenya. If there is no 'murram', look for sand (rough sand is more suitable than fine sand). Sand is fire-resistant and does not shrink. It only needs some sticky material for glueing the sand together. Use as much sand as possible and as little glue as necessary. Best glue: clay soil. In most parts of Kenya you can find clay soil in varying depths. If there is little or no clay at all, but sand is available, use sticky soil (mostly silty soil) and strengthen the binding effect by adding
If there is no sand available, use crushed stones of different sizes (from pebbles to egg size). Crushed bricks are even better. Use soil mix and crushed stones in the proportion 1:1. Mix the materials while they are dry. It works much better! Add as little water as possible. A good mix will be just a little crumbly when properly mixed, and hard when pounded into the stove-body. In areas where there are no stones, no 'murram', even no sand - use the same mixture as people use to build the mud houses but with less water! If your mix does not include stones and if your mix has only little sand, you can use the "Hip test" to find out, whether your mix is properly done: Take a hand full of your mix and compress it. The ball should get very hard, like a stone. When the ball is dropped from as high as your hip, it should keep its shape with just a few cracks. If your ball looses shape: you have too much water or too much glue. If your ball breaks: you have not enough water or not enough glue. When your mix is ready, build your stove carefully layer by layer, medium sized wetted stones then the mixture, then more stones and more mixture etc. Pound each layer into your stove and take your time doing so. Make sure that there are no soft spots, no empty gaps. Best tools for pounding, pressing and properly shaping the material:
The stove must dry for one week. The best material will crack and crumble, if you start using the stove before it is dry. Cook on the stove for one or two days, before you smear it. This gives you the chance to repair smaller cracks that might be caused, when the stove is heated up and cooled down for the first few times. If the stove is smeared at least once a month and cracks are repaired soon after they have come up, your stove will last you for many years.
[top] [end]Which plaster is best?A plaster of clay/cowdung/ash lasts long, looks smart, is easy to apply and does not cost any money. A plaster of sand/cement looks smart, needs a completly dry stove (which has been in use for two weeks already), needs an expert to mix and apply the plaster and costs a lot of money.If you use fire-resistant cement, there will be no problem. If you use the ordinary cement, you will get cracks at the hot parts of the stove after a couple of months. The bad thing about these cracks is that you can't repair them. The same mixture as is used locally for smearing either walls or floors may be used. See illustration of Maendeleo mud stoves. [top] [end]Contents: Boiling Point 16: Muds, Clays and Metals for Stove Making
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Page created:
27 August 2008; Last edited:
27 August 2008; Version: 0 | ||||||||||
Pagename: BP16:MaterialsForMudStoves-Kenya @HEDON: JENA | ||||||||||
