Salts coming through newly painted plaster wall?

[The Groutch]

As i have said, i have some fur type substance? coming through on a couple of patches of a newly plastered wall. I sealed the wall with watered down emulsion and 99% of it is fine. But these problem patches, even when the wall was first painted wouldn't accept the paint, it kept on blistering and now there is a white fur appearing, which i believe are the salts coming throught the new plaster? My question is can i sand down the patches and seal them with some sort of primer and then re paint or does the plaster need stripping back and replastering?
Thanks.

 

[JohnD]

It is efflorescence

brush them off for now don't wash off with water

wait until it is fully dry, then it will stop and you can repair if you need to.

Are you sure there is nothing making that patch of wall damp? Is it on a chimneybreast?

 

[The Groutch]

Thanks for that. If i just brush won't it come back? The wall is in a well ventilated kitchen.

 

[JohnD]

it will continue coming through until the wall is dry. then it will stop. No point in trying to do anything except brush it off until then. If you try a blocking paint it will push the paint off.

 

[joe-90]

You've got a leak somewhere. Plaster will dry out before efflorescence forms.
Have a look on the opposite side of the wall. Is your guttering leaking?

 

[The Groutch]

Thanks for the replies.
I brushed off the white "fur" and the patches are bone dry? I'll wait and see if it returns.