Can You Paint Straight onto Old Plaster?

Old plaster walls are little difficult to paint and you have to put a little more effort into the surface preparation job before you apply the first coat of paint. ... You should also use the top quality latex based paint to get the best result when painting your old plaster walls.

What happens if you paint straight onto plaster?

Applying emulsion to wet plaster also means that it may not bond properly and you could find that it peels off your wall. Painting on dried plaster can also cause the paint to dry very fast, leaving you with irregular brush strokes and an uneven finish.

Do you need to seal old plaster before painting?

You do need to seal the plaster otherwise the new paint won't stick as you point out. My first choice would be to wipe down and then paint with a coat of diluted emulsion as you suggest. You might want to try this on a section of the wall before doing the whole lot to see if you get a good finish.