Will Concrete Sealer Stop Efflorescence?

By Contractor Chem

The short answer: no sealer alone can stop efflorescence, but the right type of concrete sealer can significantly slow it down and help prevent future damage.

To fully understand how to prevent efflorescence, it’s important to know how it forms and how to eliminate its source.

What Is Efflorescence and How Does It Form?

Efflorescence happens when moisture deep inside concrete, stone, or mortar dissolves natural salts and minerals.
As that trapped water evaporates to the surface, it leaves behind white, chalky deposits — the crystallized salts we see as efflorescence.

This usually occurs when water remains trapped in or under your surface for an extended period, often from:

• Poor drainage or long-term water exposure

• Cracks in concrete or joints

• Air gaps below pavers or stone that hold moisture

Why Does Efflorescence Only Appear in Certain Spots?

Efflorescence often shows up in isolated areas because it takes time and consistent moisture for salts to dissolve and migrate.

Common problem spots include:

1. Cracked or broken joints – Letting in more water than the surrounding area.

2. Hollow or air-gap areas – Holding much more moisture than solid mortar sections.

How to Fix an Efflorescence Problem

While a high-quality sealer is part of the solution, the root cause must first be addressed:

1. Inspect and Repair Cracks or Broken Joints

   • Reinstall or inject affected stones, bricks, or tiles using a 100% mortar coverage method or crack injection epoxy.

2. Eliminate Hollow or Air Gaps

   • Tap-test the area with a wooden pole to identify hollow spots, then re-bed or inject with non-sag epoxy.

3. Remove Existing Efflorescence

   • Clean the surface with a safe acid replacement such as EffBOMB, a non-toxic and biodegradable efflorescence remover that’s safe for landscaping and the environment.

4. Seal the Surface Properly

   • Once dry and repaired, apply a breathable, impregnating, or hybrid sealer to protect against water intrusion.

Which Sealers Work Best for Blocking Efflorescence

Not all sealers are created equal — impregnating and hybrid sealers are ideal because they:

• Penetrate deep into the surface

• Block moisture from entering

• Remain breathable, allowing vapor to escape

Here are Contractor Chem’s top recommended sealers for efflorescence protection:

Surface TypeRecommended ProductDescriptionNear Salt WaterStain-Proof 40SK Densifier & Water RepellentDeep-penetrating and salt-resistantVery Porous SurfacesStain-Proof 40SK Densifier & Water RepellentStrengthens and seals porous concreteDIY UseAquaBlocka High-Performance Impregnating SealerEasy to apply, made in CanadaGlossy FinishTrident Hurricane CAT 5 2K Urethane SealerDurable, glossy hybrid sealerMatte FinishTrident Cyclone Matte RTUBreathable with natural appearanceOil + Salt ResistanceStain-Proof Premium Impregnating Sealer (Original)Strong oil, salt, and water barrier

🚫 Avoid solvent-based acrylic or non-breathable film sealers. These trap moisture below the surface, worsening efflorescence and leading to premature sealer failure.

How to Remove Efflorescence Before Sealing

Use EffBOMB Safe Acid Alternative — Contractor Chem’s top recommendation for efflorescence and grout haze removal.

✅ Non-toxic
✅ Biodegradable
✅ Safe for plants and landscaping
✅ Strong and effective

Want to learn more?
📘 Check out our full tutorial: “Efflorescence Removal Using EffBOMB Safe Acid Alternative.”

💧 In Summary

Efflorescence isn’t just a cosmetic issue — it’s a sign of water intrusion.
Fix the source of moisture, use the right breathable sealer, and you’ll stop efflorescence before it starts.