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Frequently Asked Questions
- What is efflorescence?
- How do I remove existing efflorescence?
- How do I prevent efflorescence?
- Why should I use an exterior primer?
- What primer should I use?
1. Q: What is efflorescence? White Paper
A: Efflorescence is a white, powdery substance seen on masonry substrates such as stucco and brick, often appearing a month to a year after construction is completed. What is it? Basically, it is a salt deposit. Stucco and other masonry products often contain ingredients with a high salt content such as alkali sulfates. If those sulfates come into contact with water, they mix into the water and become a salty solution. Sometimes that solution finds a path to the surface. When it gets to the surface, the water evaporates, and the salt is left behind. The salt is that white, patchy spot, otherwise known as efflorescence.
A: Efflorescence is a white, powdery substance seen on masonry substrates such as stucco and brick, often appearing a month to a year after construction is completed. What is it? Basically, it is a salt deposit. Stucco and other masonry products often contain ingredients with a high salt content such as alkali sulfates. If those sulfates come into contact with water, they mix into the water and become a salty solution. Sometimes that solution finds a path to the surface. When it gets to the surface, the water evaporates, and the salt is left behind. The salt is that white, patchy spot, otherwise known as efflorescence.
2. Q: How Do I Remove Existing Efflorescence? White Paper
A: The best removal method is with a dry brush followed by rinsing with water. You may need to hand wash with a mild detergent and a stiff bristle brush. If this does not work, try a mild solution of muriatic acid, usually one part muriatic acid (hydrochloric acid, HC1) to 12 parts water. Thoroughly presoak the wall with water. Several applications may be needed, followed by a thorough flushing of the wall of all remaining acids with clean water.
Now that the efflorescence has been cleaned from the walls, the efflorescent chain must be broken so that efflorescence does not return. The fact that we had efflorescence indicates that there are soluble alkali sulfates in the wall, and that the sulfates have migratory paths to the surface. All we can do now to prevent future efflorescence is to prevent moisture from entering the masonry and rendering the sulfates into a solution. So, the final step in this process is to seal the wall with a water-repellent primer/sealer such as SRK’s Stucco Recover. Follow the label instructions for the appropriate preparation and application procedures.
A: The best removal method is with a dry brush followed by rinsing with water. You may need to hand wash with a mild detergent and a stiff bristle brush. If this does not work, try a mild solution of muriatic acid, usually one part muriatic acid (hydrochloric acid, HC1) to 12 parts water. Thoroughly presoak the wall with water. Several applications may be needed, followed by a thorough flushing of the wall of all remaining acids with clean water.
Now that the efflorescence has been cleaned from the walls, the efflorescent chain must be broken so that efflorescence does not return. The fact that we had efflorescence indicates that there are soluble alkali sulfates in the wall, and that the sulfates have migratory paths to the surface. All we can do now to prevent future efflorescence is to prevent moisture from entering the masonry and rendering the sulfates into a solution. So, the final step in this process is to seal the wall with a water-repellent primer/sealer such as SRK’s Stucco Recover. Follow the label instructions for the appropriate preparation and application procedures.
3. Q: How Do I Prevent Efflorescence?
A: Three things must happen in order to get efflorescence.
1) There must be salts present in the makeup of the stucco;
2) There must be water intrusion that makes its way to the salts, and
3) There must be pathways for the salty solution to bleed out onto the surface.
To prevent efflorescence, you must combat at least one of these three elements. Number 1 is difficult to change. Almost all cementitious products contain alkali substances.
Number 2 can be tackled by good construction practices such as designing with overhanging eaves, copings and flashings. These structures protect the tops of the walls, and around windows and doors. To protect the walls themselves from allowing water in, use a water repellent coating such as StuccoCure. It’s also important to eliminate obvious water intrusion such as from landscaping drip systems and sprinklers.
Number 3 can be addressed by using some type of a sealer to penetrate and block the natural pores inherent in masonry surfaces which create those pathways for the salty solution to bleed out to the surface. SRK Coatings’ StuccoCure does just that. It penetrates the stucco during the curing process thereby filling the stucco’s pores, which also eliminates future cracking, another pathway for water intrusion. This specialty coating is water repellent yet breathable. Moisture from within is able to evaporate out, but water hitting the surface will not soak in.
A: Three things must happen in order to get efflorescence.
1) There must be salts present in the makeup of the stucco;
2) There must be water intrusion that makes its way to the salts, and
3) There must be pathways for the salty solution to bleed out onto the surface.
To prevent efflorescence, you must combat at least one of these three elements. Number 1 is difficult to change. Almost all cementitious products contain alkali substances.
Number 2 can be tackled by good construction practices such as designing with overhanging eaves, copings and flashings. These structures protect the tops of the walls, and around windows and doors. To protect the walls themselves from allowing water in, use a water repellent coating such as StuccoCure. It’s also important to eliminate obvious water intrusion such as from landscaping drip systems and sprinklers.
Number 3 can be addressed by using some type of a sealer to penetrate and block the natural pores inherent in masonry surfaces which create those pathways for the salty solution to bleed out to the surface. SRK Coatings’ StuccoCure does just that. It penetrates the stucco during the curing process thereby filling the stucco’s pores, which also eliminates future cracking, another pathway for water intrusion. This specialty coating is water repellent yet breathable. Moisture from within is able to evaporate out, but water hitting the surface will not soak in.
4. Q: Why should I use an exterior primer? White Paper
A: All top quality exterior primers help paint adhere better to the surface that's being painted. They do this by making the surface more uniform for the top coat, so that when the paint is applied, it can get a better "grip" than it would on the bare surface.
Primers also help give the finished paint job a more uniform appearance in terms of color, hiding and sheen. This is especially true when the surface being painted is porous or is uneven in porosity, or has a rough texture such as stucco.
If there are stains on the surface being painted, some primers can help prevent them from "bleeding" through the paint and ruining its appearance. Not all primers have stain-blocking capability. If you are interested in this feature, check the label to make sure the primer you purchase is the stain-blocking type, and read about the necessary prep work.
Some primers or sealers are capable of providing a barrier between the surface and the top coat of paint. For example, stucco often exhibits high alkalinity which can lead to efflorescence. By applying the right primer/sealer to the stucco, efflorescence will not show through the paint.
Experts say that almost any exterior painting project will benefit from the use of a top quality primer, but there are certain applications where a primer is essential: namely, when painting new wood, bare stucco, or any surface that has not been previously painted. You should also use a primer when repainting an uneven or deteriorated surface, a peeling surface, or a surface that has been stripped or is worn down to the original material.
A: All top quality exterior primers help paint adhere better to the surface that's being painted. They do this by making the surface more uniform for the top coat, so that when the paint is applied, it can get a better "grip" than it would on the bare surface.
Primers also help give the finished paint job a more uniform appearance in terms of color, hiding and sheen. This is especially true when the surface being painted is porous or is uneven in porosity, or has a rough texture such as stucco.
If there are stains on the surface being painted, some primers can help prevent them from "bleeding" through the paint and ruining its appearance. Not all primers have stain-blocking capability. If you are interested in this feature, check the label to make sure the primer you purchase is the stain-blocking type, and read about the necessary prep work.
Some primers or sealers are capable of providing a barrier between the surface and the top coat of paint. For example, stucco often exhibits high alkalinity which can lead to efflorescence. By applying the right primer/sealer to the stucco, efflorescence will not show through the paint.
Experts say that almost any exterior painting project will benefit from the use of a top quality primer, but there are certain applications where a primer is essential: namely, when painting new wood, bare stucco, or any surface that has not been previously painted. You should also use a primer when repainting an uneven or deteriorated surface, a peeling surface, or a surface that has been stripped or is worn down to the original material.
5. Q: What primer should I use?
A: Wood: On new, unpainted wood, use a quality acrylic latex or oil-based exterior primer. While quality latex primers will block stains from wood such as cedar or redwood, use an oil-based stain-blocking primer if the boards are particularly dark or highly prone to staining. Always prime and paint bare wood within two weeks of its first outdoor exposure to keep fibers from deteriorating and reducing adhesion.
When painting weathered wood, first scrape and sand the wood thoroughly, then apply a quality exterior latex or oil-based primer. When working with previously painted wood, scrape off all loose paint and feather-sand rough edges and bare spots before applying the primer.
Stucco and Masonry: On new masonry, or older surfaces that are very porous, use a water-repellent, latex masonry sealer or primer, such as SRK’s StuccoCure. If you are repainting masonry, at a minimum, spot prime where the old paint has been removed. For a uniform look, prime from corner to corner with a water-repellent, latex primer such as SRK’s Stucco Recover.
Aluminum or Galvanized Iron: First remove any white powdery oxide, using a non-metallic scouring pad or steel wool. Rinse thoroughly. If steel wool is used, every residual particle of it must be removed. Then apply a corrosion-inhibitive metal primer.
Ferrous Metals: If there is any rust, remove it with a wire brush, then rinse and allow the surface to dry before applying a latex or oil-based rust-inhibitive primer. Two coats of primer will provide added protection against future rusting.
For more information on primers or other painting topics, visit the Paint Quality Institute website at www.paintquality.com.
A: Wood: On new, unpainted wood, use a quality acrylic latex or oil-based exterior primer. While quality latex primers will block stains from wood such as cedar or redwood, use an oil-based stain-blocking primer if the boards are particularly dark or highly prone to staining. Always prime and paint bare wood within two weeks of its first outdoor exposure to keep fibers from deteriorating and reducing adhesion.
When painting weathered wood, first scrape and sand the wood thoroughly, then apply a quality exterior latex or oil-based primer. When working with previously painted wood, scrape off all loose paint and feather-sand rough edges and bare spots before applying the primer.
Stucco and Masonry: On new masonry, or older surfaces that are very porous, use a water-repellent, latex masonry sealer or primer, such as SRK’s StuccoCure. If you are repainting masonry, at a minimum, spot prime where the old paint has been removed. For a uniform look, prime from corner to corner with a water-repellent, latex primer such as SRK’s Stucco Recover.
Aluminum or Galvanized Iron: First remove any white powdery oxide, using a non-metallic scouring pad or steel wool. Rinse thoroughly. If steel wool is used, every residual particle of it must be removed. Then apply a corrosion-inhibitive metal primer.
Ferrous Metals: If there is any rust, remove it with a wire brush, then rinse and allow the surface to dry before applying a latex or oil-based rust-inhibitive primer. Two coats of primer will provide added protection against future rusting.
For more information on primers or other painting topics, visit the Paint Quality Institute website at www.paintquality.com.