Painting plaster

Hi Christine, Have you ever seen emulsion on walls where it blisters and peels off like it had only dried on the surface rather rubbery and not soaked in to the wall. A mist coat prepares newly plastered, unpainted walls to begin accepting pigment. Dry plaster is thirsty, standard emulsion paints are synthetic and lack water which plaster draws in beneath the surface. The mist coat is the paint you are using on your walls diluted down to form a base layer for the next coats to go on, do this no more blistering or peeling and a much better result with matter finishes. Leave the plaster unpainted for as long as you want I have never known it to cause problems other than skin irritations. Good idea to paint where rads will go, you may not get an exact match on some whites so stick with one producer that said even the same brand can differ over time. With luck there won't be an obvious line showing patches you painted earlier. Hope all goes well Olly

Great anser Olly. Only thing id like to add is why dont you paint the whole wall that the radiator is sitting on. That way when you come to paint the rest of the walls there is a slight different paint shade then it will be on a different wall receiving a different light so will be less if at all noticable. PPS