What to use before Plastering to prevent or lessen efflorescence?

[Markus89]

Hello everyone.

Long time browser but first time poster so sorry if its all a mess, but thanks in advance.

Right, I have just taken all the tiles off the bathroom walls which were sat on render hoping to get a plasterer in to dot and dab the walls so then i can paint/refit a new bathroom.
The plasterer has just come back to me and raised his concern regarding if he was to dot and dab straight onto the render or brick, that salt coming through may cause an issue(no sign of salt issue as of yet).
What product can I use on the brick/render to try and prevent or totally cure salt from showing once dot and dabbed then plastered?
Would a Microshield - Masonry Water Repellent work or a Salt Neutraliser be any good or would the salt come straight through this? I have searched high and low and i am struggling to find a defied answer.
Thanks Markus

 

[vinn]

Do you have outside rendered walls?
Are the walls solid or cavity?
Do you have CWI?

What state was the plaster in (presuming that its not render?) behind the tiles? Was it damp and degrading?

Your best bet would perhaps be to hack off the plaster, & go back on the clean brickwork with a mix of 3:1 sand and lime.
Then tile on top of the render.

Do you or did you have any damp issues?
Do you have an extractor in the bathroom?
Do you have any plasterboard walls in the bathroom?