Apparatus and method for the production of a plaster slurry

An apparatus for the production of a plaster slurry, said apparatus comprising:

• a mixer for mixing at least plaster and water to form a plaster slurry, said mixer comprising an outlet conduit;
• a foam generator for mixing at least air, a foaming agent and water to produce a foam, said foam generator in fluid communication with said mixer via a fluid pathway comprising a foam conduit;
• a mass flow meter, and
• a control system configured to vary the density of said foam within said foam conduit or said plaster slurry within said outlet conduit;
• said mass flow meter configured to measure the density and mass flow rate of:
• said foam within said foam conduit, or
• said plaster slurry within said outlet conduit, and
• wherein the apparatus further comprises at least one sensor configured to measure the pressure at the entrance and/or exit of said mass flow meter, and
• characterised in that said control system is configured to correct the measured density using a measurement from the at least one sensor.