You should do all you can to prevent FireCrunch getting wet before installation as there will be some water absorption. If this happens, don’t worry, it just means you will need to separate the hydrated boards from each other and allow to dry in a sheltered warm space, preferably with low humidity. The boards will not be damaged or degrade if handled correctly. Once dry, install and immediately before or after installation seal the exposed face of the board with the recommended “MgSO4 primer sealer – see recommended products. Once sealed you must use a undercoat that is part of the Dulux System paint method.
Recommended is Dulux Precision MAX ADHESION primer UNDERCOAT then use their recommended water based finish paints.