Benefits of Silane-Siloxane Sealer for Older Brick Buildings
By Mary-Grace Rosalin and Sarah Coull
A Vancouver television station, Channel M, is located in a stately brick building in the heart of the city’s bustling Chinatown. The building was in poor condition when the station’s owners undertook major renovations before moving into the five-story, 3,400 m2 (37,000 ft2) structure.
Internally, the transformation meant more than $1 million in renovations to create space for administration, production and a street-level studio. Externally, it meant removing nearly 20 years of city grime.
“We chose Kryton’s Hydropel for this project,” says Mark Melim, operations manager at All West Cleaning Services. “We’ve worked with the product many times in the past, and we’ve always been pleased with the results.”
Designed specifically for sealing brick, concrete and masonry, Hydropel is a penetrating silane-siloxane sealer that works by chemically reacting with silica- and alumina-based materials below the surface of the substrate. This reaction forms a long-lasting water-repellent barrier that protects the surface from the elements and won’t crack, peel or fade with time. And since the finished application is virtually invisible, the natural beauty of this remarkable brick building will be visible for years to come.
Why Use a Penetrating Silane-Siloxane Sealer?
Penetrating silane-siloxane sealers are composed of small and larger molecular structure that efficiently penetrates even a highly dense substrate such as brick, leaving a hydrophobic surface. Silane-siloxane bonds chemically to the pores inside and below the surface of brick and masonry substrates, keeping water from entering the brick. The penetration allows the substrate to maintain its natural texture, and the sealer will be almost undetectable on most concrete or brick surfaces. This type of penetrating sealer is highly effective in protecting structures from moisture, even in high-traffic, exposed areas. They are water based and contain minimal VOCs, which makes them an attractive option for contained areas. Due to their chemical composition and because they penetrate below the masonry surface, most penetrants are resistant to UV degradation. Most important, these types of sealers will not trap interior water vapor, as penetrating silane-siloxane sealers are 100 percent breathable.
Acrylics, silicone and epoxy coatings are some common alternatives for sealing concrete, brick and mortar in restoration projects. While these options do provide waterproofing protection, they also possess noteworthy drawbacks. Most of these alternative sealers have higher molecular structures, mostly non-penetrative, leaving a film on the substrate. While the film-forming products are effective in keeping the water from entering the brick, they face a challenge in keeping the substrate “breathable.” Acrylics perform well against UV damage, and can give the substrate a glossy, attractive finish. However, they have the tendency to darken the substrate, altering the aesthetics. Epoxies, meanwhile, have the tendency to “chalk” when subjected to UV light, thus limiting their application to interiors only. Also, while epoxies produce a durable, abrasion-resistant finish and excellent water repellence, some products are impermeable and can trap moisture. Often these products do not provide a long-term solution, degrade in the presence of high traffic and/or UV rays, and contain harmful VOCs.
What to Look for in a Penetrating Silane-Siloxane Sealer
Check for the following three characteristics when choosing a penetrating silane-siloxane sealer:
- Water based. Water-based penetrating silane-siloxane sealers typically have lower VOCs, can be readily applied, are non-flammable, and are easy to clean up when application is complete.
- Low VOC content. Penetrating sealers can vary from high VOC (more than 400 grams per liter) to low VOC (less than 100 grams per liter). Low VOCs are more user and environmentally friendly and are not considered dangerous or harmful.
- Water repellant. Water should visibly bead, approximately 90°, on the surface where the product is applied.
Always be sure to perform a small test patch to account for proper coverage application, as the properties of different substrates vary widely.
Ensure the solids content noted in the sealer is appropriate for the substrate to which it will be applied. Higher solid content works well for highly absorptive, porous surfaces, such as hollow concrete block. Most concrete surfaces tend to be denser, and using a sealer with a high solid content could lead to unwanted surface residue, as the sealer may not be able to soak in properly.
Mary-Grace Rosalin is an R&D lab technician, and Sarah Coull is a technical writer, both for Kryton International Inc. For more information, visit www.kryton.com.