The three cylinders mounted above make evident the different quailty of the soaps, as a result of their respective ingriedients.  In the end the cylinder on your right was the only soap able to carry and inscription.  The centre cylinder didnt even make it onto the machine as it was pecked at by chickens before even hardening  The various materials and the outcomes of the attempts are documented below.

A simple soap can be made from animal fat and caustic soda. The soda seen here is sold as drain cleaner. It is a highly corrosive substance and especially aggressive when mixed with water. When mixed with fat it transforms and becomes harmless. Among other factors, the subtle balance between these two elements results in various consistencies of soap.
In attempt to make a soap cylinder to capture the rush hour traffic of Berea road, the first fat used was by chance ‘Ossewit’. The combination of drain cleaner and cooking fat had produced a cylinder too soft to be recorded into. When left to set outside the cylinder was pecked at by chickens.
The central pin of the phonograph was reproduced in order to hold a thicker casting of the cylinder. As opposed to a thinner sheathe, the soap cylinders had to be thick blocks.
Mixer and bracket used for stirring fat and caustic soda mix (apprx. two hours)  
Rubber latex mould and centring device
Ossewit and Beeswax (Carnauba)
When mixing bees wax into a batch of Ossewit - then heating, a thick froth, much like that of sticky caramel was produced. This had resulted in a suitably hard, yet useless cylinder due to the morphing of the latex mold and the bubbles trapped in the surface.
The morphed shape causes the needle to miss the surface and bump its base as it spins, and the bubbles defeat the idea of a delicate recording surface.

Melt and Pour Soap
Drie Hekses ‘Melt and Pour Soap’ sets in two hours after pouring. Produced a relatively hard cylinder, which was reshaped in a lathe. The surface is receptive to the sapphire recording head but remains too malleable to allow the cylinder to be played. In effect the reproducer head eats further into the surface from which it is supposed to read, actively erasing an already bad recording.
corner describing process