Re: not enough heat

Posted by Rado (144.134.145.206)

In Reply to: not enough heat posted by Richard

Hi Richard,
Yes 2 layers of ceramic fiber blankets at thickness of 2.5cm or 1" per each layer will insulate the oven very well. Sure you can add vermiculite layer on top, it will add to insulation amount plus vermiculite layer protects ceramic blanket. Because vermiculite won't absorb water when it is mixed with cement and lime, only a small water amount is gradually added, that's why you had water dripping down - it'll dry out. Even if the mix is semi dry I use 2 newspaper pages between mixed wet vermiclulite and the ceramic fiber blanket.

The 13:1:1 recipe is not the final weather finish, it isn't strong it's light in weight insulating layer. Yes as you mentioned, for a good weather finish stucco on chicken wire can be used, or coarse sand : cement (Portland) render will do well. Finish can be painted over with limewash at the end (lime mixed in water.)
Just a one thing before doing the last weather layer (this is for ovens not boxed inside surrounding walls - e.g. I like to use building brick walls it looks good and between whose insulation is simply poured in in the dry/loose form) make sure you will fire the oven to cooking temperature at first for couple of times ( after small drying fires) for oven and the heat insulation will adjust outer structural volume/size by heat expanding, then should be the final layer applied, cracking is avoided this way. The entry building brickwork does not have to be insulated but of course this part can be covered with vermiculite or Perlite to finish nicely those shaping contours. r

brick oven Building Details page

Re: not enough heat message of 06/07/05