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Post by talltuk on Jan 11, 2014 11:42:39 GMT -8
Hi guys. Just thinking about cheaper alternatives to perlite and wondered if anyone had tried sawdust mixed into cob. Probably burn out and leave lots of nice air gaps.
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Post by Donkey on Jan 11, 2014 12:05:45 GMT -8
I have, it does.
It tends to crumble badly, but not always.
I'm in process with answering another thread that should address this, but it's taking me some time.
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Post by talltuk on Jan 12, 2014 12:08:35 GMT -8
Ok, perlite it is then. Or cat litter equivalent as have found that a bit cheaper. Gonna use sawdust for the bench base cob to provide insulation from the ground though.
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hpmer
Full Member
Posts: 240
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Post by hpmer on Jan 17, 2014 16:34:59 GMT -8
I believe cat litter is a type of clay, exactly opposite to the insulating properties of perlite.
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Post by talltuk on Jan 18, 2014 3:01:06 GMT -8
No, the white stuff is similar to perlite, expanded mineral. You can get fullers earth which is grey and very similar to clay
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hpmer
Full Member
Posts: 240
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Post by hpmer on Jan 18, 2014 5:40:58 GMT -8
Ok, that's good to know.
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Post by talltuk on Jan 18, 2014 15:50:01 GMT -8
Oh bugger. The cheap litter my wife told me about turned out to be clay basef. Oh well, vermiculite it is
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hpmer
Full Member
Posts: 240
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Post by hpmer on Jan 19, 2014 6:28:23 GMT -8
I've had good results with wood ash. Takes a while to dry out but you might consider giving that a try. 'Course it requires more than many of us keep around. ; )
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Post by talltuk on Jan 19, 2014 13:33:55 GMT -8
Hehe. Thats already part of the mix. Got two barrel loads apparently.
Gonna try a sandwich technique based around donkeys basic mix with vermiculite as the filling and hard mix the bread
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Post by esbjornaneer on Feb 27, 2016 7:20:09 GMT -8
Does anyone ever use LECA(=expanded clay pelets) instead of perlite/vermiculite? LECA is used as insulation and is recommended for insulating forges (it says on the package) and I seem to remember that it is heated to 1200degC in the production process. On an other note I'd love to find where Donkey talks about cob&sawdust or other cob mixtures for heat risers. Anyone know where I'll do that? Edit: And then I go and find the link straight away Donkey on cob mixes for rocket stoves |
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