Efflorescence on section of newly plastered wall

[Lower]

At least i assume its efflorescence......

We've just had out hall stairs and landing re-plastered on our 1920's house.

The plaster was blown in a number of places and hacked off back to the bare brick, packed out with bonding where required and then the whole wall was skimmed.

98% of the plasterwork is perfect, however there is one area below the upstairs window that had to be packed out quite considerably with bonding (maybe 50mm in places) where the old plaster was completely blown due to water ingress caused by a long since cured dripping overflow pipe.

In this area there are some salt deposits appearing on the surface of the plaster.

When the old plaster was removed the wall was completely dry but i'm wondering if the old damp problem has caused the efflorescence to occur as its taken longer for this area of wall to dry out due to the thickness of the bonding and skim.

The plaster is now nearly dry. When it is dry, am i ok to just brush off the salts, mist coat and paint or is there a special primer that i should use for this area?

Thanks in advance.

 

[Micilin]

Ideally , where you had damp, a sand and cement coat with an additive that would stop salts was the way to go, as your bricks would still be contaminated with salts. 1920s solid 9" brick ? Bricks in good nick? With 50 mm to go on, you could have scratched it out with a couple of coats and then bonded it. 50mm is a lot of gear, and it's debatable whether you needed eml on the wall. A breathable lime render is often reccommended on old brickwork.

That's no good to you now, though.

I would be inclined to wash off the salts and wait for them to reappear before painting. Painting over them won't do any good now.

Do you have any dark patches on that dried out area, or just salts. Are they in one solid area, or are they around the edge of an area?

It may be as you say that the gallons of water used in plastering are taking a while to dry out - and in the process drawing out the salts in the bricks.

Are you sure no ingress under the cill or anywhere else - the down pipe might be fixed but is the actual place where the water got sealed up - perhaps pointing, brackets for downpipe, hole around window.

 

[Lower]

My impression is that it is just taking a while to dry out as it appears to be drying at the same rate as other areas where there was a fair bit of bonding used.

Only this area has the salts appearing though.

I'm not planning to paint until the area is fully dry, i've removed the salts and they haven't reappeared. The leak is long since fixed and the penetration problem was down to the way the water was splashing up under the cill. The wall was bone dry prior to plastering.

But once the salts have stopped appearing and i've removed them all, can i just mist coat the wall as normal or is there a special primer i should use.

 

[Micilin]

My impression is that it is just taking a while to dry out as it appears to be drying at the same rate as other areas where there was a fair bit of bonding used.

Only this area has the salts appearing though.

I'm not planning to paint until the area is fully dry, i've removed the salts and they haven't reappeared. The leak is long since fixed and the penetration problem was down to the way the water was splashing up under the cill. The wall was bone dry prior to plastering.

But once the salts have stopped appearing and i've removed them all, can i just mist coat the wall as normal or is there a special primer i should use.

I'd say if they have stopped, and no ingress you can mist/ paint it as normal - but give it plenty of time - check on the decorators, they'll let you know.

 

[Lower]

Thanks for your input. Much appreciated.

I am the decorator and i didn't know the answer hence my post.