[Terrapreta] OT Fiber re-inforced ceramics

[rukurt at westnet.com.au]

> Michael Bailes wrote:
>   
>> http://www.scielo.br/scielo.php?pid=S0044-59672004000200004&script=sci_arttext 
>>
>>     
An interesting bit of information comes out of the above article.

The "cauixi" mentioned is a freshwater sponge. Sponges have 'skeletons' 
consisting of tiny needles (spicules) of SiO2----- glass to you. The 
photomicrographs quite clearly show these little needle like structures 
in the pottery made with cauixi. Embedded in a matrix of clay, these 
quite simply operated as glassfiber reinforcement, not unlike the glass 
fiber reinforced plastics we often see in things like automotive rear 
vision mirrors and other, often injection moulded, plastic parts.

As well, it appears that the clay was not fired to very high 
temperatures and therefore not fully vitrified, but the cauixi spicules 
would have done a lot to strengthen the resulting pottery quite 
substantially. The spicules apparently are also hollow, which would have 
added to the porosity of the resultant pottery material, further 
enhancing it's ability to soak up nutrients from the foods that were 
cooked or stored in the containers made from it. Additionally, silicon 
would have been available as a nutrient for plants from them, once the 
wee beasties had quarried it out of the pottery.

The cariape was a siliceous ash that was also added to pottery, thereby 
increasing the store of silicate in the TP soils, making it available to 
plants, via the wee beasties efforts.

Silicone is a micro nutrient of some importance to plants, but really 
only recently recognised as such. It increases plant stiffness and also 
gives increased disease resistance.

Untempered clay shrinks and distorts considerably in drying and firing 
and consequently potters add other materials, such as sand,  and in the 
case of the relevant amazon area, crushed rock, cauixi and cariape, thus 
producing a usable pottery clay that could be effectively made into 
vessels. I suppose, eventually someone noticed that garden plots which 
contained cast off pottery sherds produced greater yields and as, with 
the charcoal, people began adding the sherds on purpose.

If we want to emulate them, we might have to make and burn their 
equivalents from clay, tempered with the rock dust that organic growers 
use to re-mineralise their soils and perhaps the siliceous ash from 
burned grass or bamboo. Perhaps even incorporate ground bones in the 
clay. If using a TLUD type charcoal burner the clay blanks could perhaps 
be mixed in with the biomass that is to be pyrolised


Kurt