In broad terms, there are two options for creating specialised surfaces: precasting and post-casting. Precasting is the skill of creating a mould that forms the invert of the desired surface, whereas post-casting is a process conducted on the element after demoulding.
Combining the 3D capability of sprayed GRC with exposing the aggregate is popular for both renovation projects and new buildings. The exposed aggregate creates a less uniform surface and adds texture to elements. Typically, four different techniques are used to expose the aggregate: grinding, sandblasting, retarder paper and washing. Previously, acid etching was also frequently used; however, this is now in steady decline.