Painted surfaces already damaged by efflorescence must NOT be repainted until the source of the moisture is identified and eliminated or blocked (by waterproofing). It may be necessary to engage the services of a qualified waterproofing specialist.
Once the water source is eliminated, most efflorescence (also called Calcium Carbonate or limestone) can be removed with abrasive techniques. Dry brushing, light water blasting or light sandblasting followed by flushing with clean water. In large areas, rotary scrubbers with scrubbing pads may also be used.
Penetrating sealers are the best defense against efflorescence. These silicone-based sealers work by penetrating the surface and reacting with free lime to form calcium silicate. It's like filling the capillaries and pores with cement to block the migration of water.
In all but very extreme cases, efflorescence will stop as capillaries in the stone become blocked by crystallized salts. Once the process stops, the white deposits will eventually wear off with use and exposure.
The acidity in the vinegar helps remove the efflorescence and calcium deposits by breaking down mineral crystals. After cleaning the surface, let dry for 48-72 hours (moisture content below 25%).
We were told a diluted CLR solution would work. We tried this and it was a lot of work to scrub the surface clean of the residue and you have to be sure to rinse immediately because technically CLR is not for painted surfaces.
Any efflorescence on the surface must be removed prior to painting as it is regarded as a poor and friable base that prevents paints and coating systems from adhering effectively.
Efflorescence must be removed before applying a penetrating sealer.
Apply a quality water-based or solvent-based masonry sealer and allow it to dry completely; then apply a coat of top quality exterior house paint, masonry paint or elastomeric wall coating. Dulux recommends the use of Weathershield® Matt for exterior surfaces.
Clear water repellents, silicone and acrylic coatings also may help you remove efflorescence as well. The coating will absorb water across a masonry surface and prevent efflorescence from recurring. Plus, the combination of warm water and white wine vinegar has been shown to eliminate efflorescence.
Before painting or renovating walls, the surface needs to be clean by removing all previous salt deposits and fully cured.
Remove loose material by scraping or brushing with a stiff bristle brush to a sound edge. Remove any efflorescence with a suitable efflorescence remover / brick cleaner in accordance with the manufacturer's instructions. Rinse the surface thoroughly with clean water.
An acidic cleaner, such as PROSOCO's Sure Klean Light Duty Concrete Cleaner, and Sure Klean Vana Trol can dissolve efflorescence more effectively.
Efflorescence itself isn't dangerous or harmful. It can lead to potential moisture problems that can cause structural damage to building materials. So it is important to take action when you notice efflorescence in your basement, on your paving stones, or on other structures.
Similar to vinegar, lemon juice contains citric acid, which can effectively break down efflorescence. Squeeze fresh lemon juice onto the affected area and let it sit for a few minutes. Again, use a brush or cloth to scrub away the deposits gently.
100% solids Vapor Barrier Epoxies may help to hold back efflorescence as they are engineered for high tolerance to chemical attack. Their performance will be predicated on how well they resist degradation from the highly caustic solution stemming from the water and soluble salt solution.
Once the surface is completely dry, you can apply SEALTIGHT or ULTRA MASONRY BLOCK SEALER to waterproof the surface and help keep efflorescence from forming again in the future.
In these cases, water repellency is critically important. In these situations, use LastiSeal Brick & Concrete Sealer for an unbeatable 15-years of protection, or go for DryWay Water-Repellent Sealer, which is a DOT approved silane/siloxane water-repellent. Efflorescence is a very common and controllable condition.
If you see a white powdery substance (as you will see below), it is natural salts present in the masonry and is the biggest enemy of any waterproofing job. The white powdery substance is efflorescence, and you want to neutralize it with DRYLOK Etch which is much safer than muriatic acid.
High psi cleaning can remove efflorescence; however, you need to be careful not to use psi levels that are too high as that can make the situation worse and actually make the surface more permeable. Stick to no more than 2,500 psi for this job.
Despite the appearance of stains or marks on the surface, it's important to note that efflorescence will not compromise the strength or durability of your concrete pavers. Its impact is solely aesthetic and temporary in nature.
It is the same way on internal walls to clean. Here are a few examples: Baking soda: Mix baking soda with warm water to create a paste, then apply the paste to the affected area with a stiff-bristled brush. Allow the paste to sit for several hours or overnight, then rinse the surface with clean water.
To remove the efflorescence, I suggest using Crommelin 4L Efflorescence Remover in combination with a stiff bristle brush. Please make sure to follow application instructions and allowing the product to activate first. If washed or removed too early the product will not work properly.
A stiff scrubbing brush and a dry brushing technique will remove the efflorescence. Muriatic acid can be used for efflorescence removal, but it poses risks such as discolouration and potential surface damage. Consider safer commercial solutions.