Efflorescence can present as a cosmetic problem but can sometimes also indicate an internal structural weakness in masonry substrates, and/or an issue with moisture ingress. Ensure any moisture ingress is addressed before attempting to remove efflorescence.
Initially, try to remove as much efflorescence as possible with a dry stiff bristled broom. If the efflorescence has hardened around surface cracking, then scraping with a steel scraper or similar may be required.
Using warm water can soften efflorescence and make removal easier. The use of a weak solution of hydrochloric acid (15 to 1) may also assist in effective removal. Care should always be taken regardless of removal method used to ensure that no damage to the coating occurs.
When using acid solution, flood wall first with water and only allow the acid solution to have contact with the wall for a short time. Use acid strictly as directed by the manufacturer. DO NOT ADD WATER TO CONCENTRATED ACID.
In some cases where efflorescence is extensive and widespread, the use of a pressure cleaner may well be of benefit, but psi should not be sufficiently high as to damage the paint coating. Once efflorescence has been removed, the affected areas should be primed with Rockcote Anti Efflorescent Primer and then repainted or touched up with a suitable topcoat.