Insulation tests (Vermiculite mixed with Starch)

This week we conducted tests on stablizing vermiculite by binding the particles together using a starch mixture.
We used cassava flour, mixed it vermiculite using a 3:1 ratio and dried it then fired it on a local charcoal stove.
Results so far show only the point close to the heating source burns away which would require more insulation at the heating point close to the heating element.
Upon drying the insulation becomes hard however under immense pressure it can crack.