The substrate need to be prepared in the same manner as for traditional render, eg to be clean and free from dust or loose materials, paints should be removed, etc
In order to increase the Bauwer Light lock on the smooth substrates, a key coat could be applied (1:3:3 cement/lime/sand or similar) to the 70%-80% of the substrate surface. The idea is to increase the contact surface with light-weight Bauwer Light so it locks to the smooth substrate.
We'll be launching coloured range of renders in December both as a finish to our Bauwer Light (Arenino) and as a separate one coat system (Mono Chrome), similar but more breathable vs Monorex GM. Those finishes are produced by our Italian manufacturer (Northern Italy, close to France border) and being very popular in both France and Italy, were they successfully compete with French made materials like Parex as Mono Chrome material is more breathable and designed to withstands harsh coastal weather.