Sprinkle the gypsum slowly and evenly over the surface of the water. If the gypsum is sprinkled too quickly, lumps may form which are difficult to dissolve, even with further stirring. Leave the mixture to stand for about 1–2 minutes so that all the gypsum becomes evenly wet and any air bubbles can escape from the mixture.
Then stir the product thoroughly until you have a lump-free mixture.
Use mechanical stirrers and hand blenders to mix large quantities. The mixing time depends on the size of the mould and the size of the mixer.
Ensure that the mixing time is never less than one minute, even with small quantities.