We recommend applying an appropriate primer when your plaster is fully dry and ready for painting. The primers we recommend are Tikkurila Optiva Primer (thinned with no more than 5% clean water) or Colourtrend Prime 4 (thinned with approx. 10% clean water). These primers will soak into the bare plaster and anchor themselves to the substrate leaving you with the perfect base for your topcoat.