A polyimide material comprises a polyimide. The process involves introducing bitumen froth into the froth tank; rotating at least one movable picket through the bitumen froth; recovering the upper bitumen-rich, reduced-solids layer; and withdrawing the lower concentrated solids layer from the tank. The pump is provided with the following to limit pulsing: a low force slow return velocity return spring ; enlarged fluid passage ; elastic bumper ; and, a ratchet tooth bearing against the stem. The image data input unit stores the image data into a first area in the external memory. In a first mode, the first fastener engages the third fastener and the second fastener engages the fourth fastener to attach the pocket assembly to the first substrate.