Prevent Damage and Add Color with a Masonry Sealer

A masonry sealer is very different from clear wood sealers, wood stains or common house paints. All masonry components have an alkaline PH, this is opposite of wood which is slightly acidic. A high PH isn’t tolerated very well by normal house paints or wood stains.

The primary goal of a masonry sealer is to stop liquid water from entering a hard masonry surface but also allow any accumulated water vapor to escape before any damage can occur. Water can readily damage most masonry surfaces after a few years of exposure.

In both its liquid or vapor form, water can cause cracking and change the alkaline nature of masonry materials. This will drastically weaken the hard material.

Water damage is very hard to fix once it has happened. Using an appropriate sealer can prevent much of this damage before it occurs and is much cheaper than the repairs after the fact.

Water damage can shows up as white chalky areas or streaks. This is called efflorescence and is deposits of calcium salts that are an important ingredient of stucco, brick, concrete block (cinder blocks) and concrete. Water dissolves these salts and transports them to the surface. If the surface is painted, blistering and eventual peeling will be evident as well. These areas can be soft and easily scraped.

Choosing a Masonry Sealer Depends On
Where It’s Used and the Desired Visual Effect

Any masonry surface can receive a sealer but most products are intended for either horizontal surfaces such as floors or vertical surfaces such as walls. Plus some products are intended for interior use only or exterior use only.

The main types of sealers available are clear penetrating coatings, pigmented coatings and film forming products. All are available in either water base or oil base formulations. Painters favor the acrylic products because the formulations allow water vapor to escape and stop liquid water from entering the surface. Plus they are easier to apply.

Clear sealers can deepen or enrich the color of the surface, but usually will not be visible. These are water sealers and are designed to repel liquid water, but they are not waterproofers. Water vapor will still move through the material.

Water sealers stop liquid water from entering the surface, but allow water vapor out. They are breathable products that can be applied to brick, concrete block, stucco or any masonry material such as stone. Some are designed for use on floors, making them very useful for sealing decorative concrete stains.

Another type of clear masonry sealer is designed to combat graffiti. In this case the sealer is applied in several coats, typically 2-3. The final coat is a sacrificial coat that is pressure washed off with the graffiti. Another coat is applied after the surface has dried. This sealer forms a clear unnoticeable film.

Pigmented coatings are very similar to stains in many ways and can be water sealers or waterproofers. It is possible to change the color of masonry materials and provide waterproofing at the same time. Very appropriate for renewing brick or as an alternative to paint for stucco, concrete block buildings or concrete floors.

The intensity of color can be subtle to solid. This is similar to semi-transparent and solid color exterior wood stains. Can be applied to any masonry surface.

Film forming coatings are more like paint than a stain. They can have a sheen from satin to gloss. These products are waterproofers and some can resist water pressure behind the film. This is very useful for sealing leaky basement walls. As a masonry sealer, a film-forming coating will usually last the longest.

Two examples of film forming coatings are elastomeric paint or epoxy floor coatings. This type of coating can be applied to any horizontal or vertical surface. Check the product label for recommendations as for use on floors. Not all products are suitable to be walked on.

Applying a Masonry Sealer

Brush, roller or airless sprayer can apply all of these different products. Typically spraying is used on vertical surfaces such as walls for an even application, with back rolling or back brushing immediately following the application if needed. Floors should be rolled at the recommended coverage rate.

Before any masonry sealer can be applied, the surface must be cleaned and dry. Pressure washing and some hand scraping can remove the dirt, mold or peeling coatings. If it's not properly cleaned the sealer or coating will not last. Don't rush during cleaning or application. All of these products must be applied according to manufactures instructions and only to fully cured masonry surfaces.