One of Manzoni's friends, Agostino Bonalumi, claimed that the tins are full not of faeces but plaster. The cans are steel, and thus cannot be x-rayed or scanned to determine the contents, and opening a can would cause it to lose its value; thus, the true contents of Artist's Shit are unknown.
One of Manzoni's friends, Agostino Bonalumi, asserted that the tins contain not feces but plaster. The cans are made of steel, rendering them un-scannable and preventing their contents from being revealed by x-ray or other methods. Opening a can would also diminish its value, making the true nature of Artist's Shit a mystery.