How to Remove Efflorescence Staining from a New Brick Wall

Efflorescence — those chalky white streaks or powdery deposits on your new brick wall — is very common and, in most cases, completely treatable as a DIY job. It's caused by soluble salts migrating through the masonry and crystallising on the surface as water evaporates. The good news is that on new brickwork it often clears up on its own over time, but there are steps you can take to speed up the process and prevent it from coming back.

What Causes Efflorescence?

When water moves through brick, mortar, or the substrate behind the wall, it picks up naturally occurring soluble salts (such as calcium sulphate, sodium sulphate, or potassium sulphate). As that water reaches the surface and evaporates, the salts are left behind as a white, powdery or crystalline deposit. On a newly built wall, this is especially common because:

• Fresh mortar contains a high concentration of soluble salts
• New bricks may still be releasing salts from the manufacturing process
• Construction moisture is still working its way out of the wall

Efflorescence is primarily a cosmetic issue, but persistent or recurring deposits can sometimes indicate a moisture problem that needs further investigation.

Step 1 — Let the Wall Dry Out First

Before reaching for any cleaning products, give your new wall time to dry. Attempting to clean efflorescence while the wall is still damp or actively wetting and drying will likely make the staining worse. Ideally, wait for a period of dry weather — at least a week or two — before starting treatment. In New Zealand's wetter regions (West Coast, Northland, Wellington), this may take longer.

Step 2 — Dry Brushing

For light or fresh efflorescence, dry brushing is often all you need:

1. Use a stiff-bristled brush (natural or nylon — avoid wire brushes on softer bricks as they can scratch the surface)
2. Brush the deposits firmly in a circular motion to break up and dislodge the crystals
3. Sweep or vacuum away the residue
4. Repeat after the next dry spell if deposits return

Many cases of new-build efflorescence will resolve with dry brushing alone over several months.

Step 3 — Washing with Water

If dry brushing isn't enough, a clean water wash can help:

• Use a garden hose or low-pressure washer (avoid high-pressure washing on new mortar joints, as it can erode them)
• Wet the wall thoroughly, scrub with a stiff brush, then rinse from top to bottom
• Allow the wall to dry completely before assessing whether further treatment is needed

Step 4 — Dilute Acid Cleaning (For Stubborn Staining)

For persistent efflorescence, a dilute acid wash is the standard trade approach. This is where you need to be careful.

Commonly used products include:

• Dilute hydrochloric (muriatic) acid — typically a 1:10 solution (1 part acid to 10 parts water — always add acid to water, never the reverse)
• Proprietary brick and masonry cleaners available from Bunnings or Mitre 10, which are often safer and easier to use than raw acid

Safety precautions are essential:

• Wear chemical-resistant gloves, safety glasses, and old clothing
• Work in a well-ventilated area
• Pre-wet the wall before applying acid solution to prevent it soaking in too fast
• Apply the solution with a brush, allow to dwell briefly (follow product instructions), scrub, then rinse thoroughly with plenty of clean water
• Neutralise with a dilute baking soda solution if using raw acid
• Keep acid away from painted surfaces, metal fixings, and plants

Refer to WorkSafe NZ guidance if you're handling concentrated acids, and always read the product Safety Data Sheet (SDS).

Choosing a Proprietary Cleaner

If you'd prefer to avoid raw acid, look for dedicated efflorescence removers at your local hardware store. Products from Sika and similar brands are formulated for masonry cleaning and come with clear dilution and safety instructions.

Step 5 — Preventing Efflorescence from Returning

Once the wall is clean and fully dry, consider these preventive measures:

For guidance on moisture management in masonry construction, BRANZ publishes excellent technical resources for NZ conditions.

NZ Building Code Considerations

If your brick wall is part of an exterior cladding system, it must comply with NZ Building Code Clause E2 (External Moisture). Persistent efflorescence on a cladding wall could indicate a moisture management issue that goes beyond surface staining. If you're seeing damp patches, mortar deterioration, or recurring heavy deposits, it's worth having a professional assess whether the wall is performing as required. Check MBIE Building Performance for information on the Building Code and when a building consent may be required for wall repairs or modifications.

When to Call a Professional

While efflorescence cleaning is generally a safe DIY task, call a qualified bricklayer or stonemason if:

• The staining is severe, recurring, or spreading despite treatment
• You notice cracking, spalling, or mortar deterioration alongside the staining
• There are signs of ongoing moisture ingress or damp inside an adjoining structure
• You're unsure whether the wall meets Building Code requirements

A licensed bricklayer can assess whether the root cause is a construction issue — such as missing or faulty DPC, incorrect mortar mix, or inadequate drainage — and carry out any remedial work properly. You can find qualified local bricklayers on tradedirectory.co.nz.

Sources & Further Reading

• BRANZ — Masonry and moisture guidance
• MBIE Building Performance — NZ Building Code
• WorkSafe NZ — Safe handling of hazardous substances
• Sika NZ — Masonry and construction products
• Bunnings NZ — Masonry cleaners and sealers
• Mitre 10 NZ — Brick and masonry care products