powder when wiping emulsioned wall with hand?!

[gemmabuild]

Hihihi - newly plastered walls were painted with matt white emulsion about 3-4 months ago. I've never noticed until someone pointed out that if you brush your hand on the wall, then you get a white powder residue on your hand. Some walls are particularly "powdery" whereas other walls have no powder when hand-wiped....
does anyone know why that is?!

is it a big problem??
do I need to paint the wall with emulsion again?

THANKS A MILL!!x

 

[TheDec]

gemma, if the applied emulsion was a contract emulsion this can often appear chalky to the touch, was the plaster skim completley dry prior to painting.

Dec

 

[gemmabuild]

Dec - that's exactly how it feels "chalky". The builders used Wickes emulsion.... do you think this would tend to be chalky to the touch?

I have a feeling in some rooms they may not have left enough time for the plaster skim to dry properly before painting.... does this also end in this white chalky dust?

Is it a big problem? Is it the emulsion itself that's dusting off? and does that mean another coat needs to be painted? and should i buy another brand other than wickes to stop the "chalk"?
any other solution most appreciated!!
Thanks v much

 

[TheDec]

gemma,

Applying emulsion to damp plaster can and will often cause this to happen, this time go for trade emulsion. lightly sand the walls and dust off, apply your first coat thinned approx 10% and subsequent coats approx 5%.

Dec