This is one of life's little mysteries. Acetone works as both an accelerator and as a debonder.
According to the MSDS, E-Z Bond regular accelerator is about 68% acetone, 15% propane, and 14% n-butane. Oddly, the MSDS for the mild accelerator gives the same formula although the two are definitely different. The debonder is pure acetone.
Regards,
Eric