Will Concrete Sealer Stop Efflorescence?

No sealer alone will stop efflorescence, but the right concrete sealer will slow it down substantially.

The only thing that will stop efflorescence completely is stopping its route source, which is water deep in the concrete, stone, or bedding mortar that is allowed to saturate for long periods of time. To really get to the bottom of the efflorescence blocking topic, we first need to understand how it works in the first place. 

How is Efflorescence Formed?

Efflorescence forms when water which is able to stay saturated in a stone or concrete surface for an extended period of time, dissolving the natural salts and free chlorides in the surface. When the water that dissolved all those minerals finally comes to the surface to evaporate after a few sunny days, the water is able to evaporate but leaves the newly crystallized salt and chlorides behind, forming what we know as efflorescence. 

Why Does Efflorescence Only Happen in Certain Areas?

This is due to the time that it takes for saturated water to actually dissolve the salt and chlorides. Not nearly enough water to dissolve that amount of material gets through just by surface saturation alone, and especially not in a well installed decking or siding system. 

The two big reasons for efflorescence happening in an area are:

1. Broken joints or cracked stones allowing water to flow in at a higher rate to a more absorbent part of the system like thinnest, bedding mortar, or the structural concrete slab below

2. Air gaps in the mortar or slab of any area of a deck or siding system, no matter the type of masonry, that has a hollow or air gap will hold a substantial amount more water than could possibly be absorbed by the same system with no hollows. 

How Can I Fix an Efflorescence Problem?

While sealer is an important part of any efflorescence remediation strategy, the biggest thing will be to solve the route source of high water absorption and storage in the system. This will require inspecting and repairing any cracked or broken joints, stones, or bricks; as well as tap testing the area with a wood pole to listen for hollow or mislaid tiles / stones / bricks. All of these hollow areas should be either removed and reinstalled correctly using a  100% mortar coverage style, or injected fully to rejection with a high quality crack injection epoxy that is non sag nor expanding. After solving your water absorption and storage issues, now it is time for sealer to extend the life of the whole system and stop normal surface absorption of water which can still cause mild efflorescence.

Will any Type of Concrete Sealer Work for Blocking Efflorescence?

No, there are specifically two types of sealer which are best suited for blocking efflorescence in a stone or concrete surface, and one type that can actually make the situation worse. Impregnating and hybrid sealers are the best way to protect against efflorescence in a masonry system, as they sink deep into the stone or concrete and block water from both sides, while also letting water vapour still evaporate through, any high quality impregnating or hybrid sealer will be breathable but here is the list we recommend for people with efflorescence issues:

Best near salt water: Stain-Proof 40SK Densifier and Water Repellent 

Best on Very Porous Surfaces: Stain-Proof 40SK Densifier and Water Repellent

Best for DIY: AquaBlocka Made in Canada High Performance Impregnating Sealer

Best Glossy Hybrid: Trident Hurricane CAT 5 2K Urethane Sealer

Best Matte Hybrid: Trident Cyclone Matte RTU 

Best Oil + Salt Resistant: Stain-Proof Premium Impregnating Sealer (Original)

Any type of solvent based acrylic or other non hybrid film forming sealer (big box brands claiming a colour enhancement, gloss, or wet look) that do not sink into the surface at all will make efflorescence problems worse as they are not breathable and cannot let water escape. This often results in worse efflorescence problems, as well as premature sealer failure. 

How Can I Remove Efflorescence Prior to Sealing and After Repairs?

The best method is to use a high quality safe acid replacement like EffBOMB. EffBOMB is our personal choice and highest recommendation for efflorescence and grout haze removal, as it is a safe acid alternative, non toxic, easy to use, and 100% biodegradable formula safe for your landscaping and the planet. Want a more in depth how to on using EffBOMB? Click here to get a full efflorescence removal tutorial using EffBOMB safe acid alternative.