Glazed Maputo Ceramic Stove
Crispin Pemberton-Pigott, New Dawn Engineering, August 23, 2006
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This is a picture of a glazed MCS 200 (200 mm in diameter) which was made this week in Maputo.
The idea is that the stove should not look 'like a ceramic stove' but more like a casserole or a serving dish, something perhaps one would find in a kitchen rather than out in a shed.
There are several things that need to be improved. The powdering of the ingredients needs to be improved before mixing. The charcoal in particular is not fine enough (cavities too big I think).
The mix was formed on a potter's wheel which is definitely not in the manufacturing plan - too wet. It is an interim measure to get some prototypes for marketing surveys. It should be damp-formed in a press which will increase density and strength and reduce cracking.
The little 'wings' that the grate sits on are too plentiful - only 4 to 6 are required. They are attached after the potter is finished. Because it dried very rapidly (2 days instead of 5-7) they were added a little too late. This led to cracks appearing at the wing-body joints. Fortunately it is very strong but still, it is something that can be timed better.
I like the 11 hole grate. We made some with 9, 11 and 13 holes to look for differences in performance. The centre hole is slightly larger than the others.
I believe the glazing was fired to 1050 degrees.
The pattern happens to match a dish and plate set. Conceivably it could be made to match other kitchen plate sets for a standard fee (i.e. a marketing gimmick). We might still add handles if research shows they are needed. I measured a maximum temperature at the outside bottom of 110 degrees. The air preheat seems to have been over 200 degrees, and the maximum temperature at the top of the body was 220 on the outside. The light colour of the glazed one will raise the temperature by reducing radiation losses. This is good and bad. We could put an insulative sleeve around the upper sction....lot of possibilities.
Regards from the summer sun in Dakar by the sea.
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