New surfaces:
New plaster or patching must be aged, clean, dry and without chalking. If mildew is present, treat the surface with a suitable restoring product. Remove any efflorescence by brushing or washing. Prime clean surfaces with acrylic fixative like IMPRIMITURA ACRILICA diluted 1 to 8 with water. For the exterior it is recommended a solvent-based fixative like PRIMER / P diluted at 20-25% with Synthetic Thinner
Painted surfaces:
Remove the painted parts in phase of flaking, in the case of lime-based or tempera paints provide for the total removal by washing and brushing.