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Post by patamos on Dec 10, 2015 23:28:20 GMT -8
NOt sure if this is old news to some, but i recently threw these three together in roughly equal parts with amazing results. Makes for a very workable putty that does not shrink (much) or crack (at all!) and maintains its integrity very well once fired. Funny that i've had the manure and vermiculite sitting in bags next to each other for years…  |
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Post by oxbowfarm on Dec 11, 2015 2:44:41 GMT -8
For use as a plaster?
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Post by patamos on Dec 11, 2015 9:11:37 GMT -8
For use as a shapable high heat insulation and/or castable heat riser. Might not be up to all the knocks and bumps that occur in a feed chamber. Adding sodium silicate could help that.
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Post by respire on Dec 14, 2015 4:43:40 GMT -8
Thanks for sharing patamos. I was familiar to the use of manure in cob for plastering walls etc... But was wondering if this was suitable for high temperature areas, as the fibres / organic parts will gasify and thus weaken the structure. But perhaps that's not a concern as the biding role of those fibres is mostly useful before the clay has been hardened by firing at high enough temperatures. Any thoughts? Also, I read from someone using a perlite / clay mix, that the perlite will melt at high temperature, leaving a thin and smooth layer of glass inside of the burning chamber / heat riser. Do you also notice a similar phenomenon in your vermiculite version? |
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Post by patamos on Dec 17, 2015 7:58:38 GMT -8
Hi Respire, Welcome to the boards  The folks at Aprovecho research centre, and Donkey and others in the earlier days of this forum… have done a fair bit of high temperature testing of these composites. Yes, the manure fibre does burn out, leaving dead air space. So long as the clay structure can maintain its integrity you thereby have an insulated casting. This will not hold up to the rigours of knocks and bangs in a feed chamber, but should do in other areas. Matt Walker has written of success combining clay, perlite and sodium silicate. Karl (one of the brighter scientific minds contributing to this forum), has earlier cited that perlite will melt at 800c and vermiculite at 900c. Whether this is immediate or after prolonged exposure i do not recall. A 6" batch box might achieve these temperatures in the hottest area of the core. 8" batch box very likely. J-feeds probably not... What i like about the clay, manure, vermiculite recipe is its workability. I used to steer clear of vermiculite because of how much it swells and shrinks with water content. But the horse manure stabilizes the mix very well. Perlite and clay is also quite stable, but i do not like dealing with the dust. One of those situations where i ought to find and put on my mask but usually don't bother... |
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