Powdery Walls on Renovated Property

[the_kilo_1984]

Hi all!

We've recently moved into a property that had been renovated by previous owner (a property developer). All of the walls in the house are white but have a powdery material on the surface that marks clothing etc. when brushed against it.

We are planning to repaint every wall in the house, our current method of preparation has been to give each wall a thorough wash with a sugar soap solution and sponge and rinse with clean water. We have prepped 2 rooms so far and are just about ready to paint. Is there anything else to do before painting with our coloured matt emulsion?

My worry is that the new paint starts to flake or powder again just like the original stuff. The walls are plastered and the washing seems to have taken care of the powder for now. There is a very light dust in some areas but I think this is down to the air particles settling back down after washing. The dust/powder was on the blinds and dust sheets.

Any advice would be much appreciated,

Thanks!

 

[misterhelpful]

The paint used sounds like it is a contract matt emulsion. It is ideal for use on new plaster (is that what it was used on?) as it can be applied whilst the plaster is still drying out, it is also cheaper than vinyl emulsions but the downsides are that it does have a slightly chalky/powdery finish and it cannot really be cleaned/wiped successfully, without leaving marks.
It is ok to be left as a finish coat on ceilings, which tend not to suffer from wear and tear, but on walls it is not hard-wearing enough for everyday use, unless you are an extremely careful person with no kids or pets.
If this is the situation with what is already on there, there is no reason why you can't apply a vinyl emulsion directly over it. However, if there are any particularly chalky/powdery areas, I would advise you to wipe away as much of dust as possible before doing so.