There is described a duplex image-forming apparatus having a function of forming images onto both sides of a transfer material. According to the invention the conversion phase comprises at least: one first sub-phase during which the amplifier is connected to the input stage and the amplifier is disconnected from the output stage; followed, by a second sub-phase during which the amplifier is disconnected from the input stage and the amplifier is connected to the output stage. The metal oxide particles may be coated with a hydrophilic coating, and the pre-dispersion may contain at least one surfactant to aid in the dispersion of the metal oxide particles. A jam access cover pivots on the main transport cover from a closed to an open position. Code configured to transform the content page from the first state to a second state may be received.