Common Concrete Sealer Problems
Dealing with issues related to concrete sealers is often a challenge for homeowners, particularly when the final appearance or functionality falls short of expectations. Typically, these issues stem from either applying too much sealer, using it under less than ideal conditions, or accumulating multiple layers over time. Here, we explore some of the common problems encountered with concrete sealers, their causes, and strategies for prevention.
Formation of Bubbles in Sealer
Bubbling in a concrete sealer is often the result of applying the sealer too thickly. The process of outgassing, or the release of air from the concrete, requires the ability to pass swiftly through a thin layer of wet sealer. Ideally, a single coat of an acrylic concrete sealer applied at a standard rate of 300 square feet per gallon should measure approximately 5 mils in wet thickness, reducing to about 2 mils once dried. Over-application impedes the escape of air, leading to bubble formation. Moreover, bubbling can occur if the sealer is applied during hot conditions or on concrete exposed to direct sunlight, causing the sealer to dry prematurely on the surface and trap solvent beneath, which then tries to escape and forms bubbles. To mitigate this, it's advisable to apply sealer in cooler conditions and away from direct sunlight.
Solvent-Based Sealer Whitening, Peeling or Flaking
Whitening, or "blushing," of a solvent-based sealer can result from applying it to a wet surface or freshly laid concrete that hasn't fully cured. This prevents the sealer from adequately bonding to the concrete surface, causing it to sit atop a layer of water. Additionally, applying thick layers of sealer or reapplying it multiple times over the years can trap moisture beneath, leading to loss of adhesion and a whitened appearance as the moisture and air beneath the sealer alter its appearance. To prevent this, adhere strictly to the manufacturer's guidelines on application rates and coat numbers.
Lap lines and Roller Marks
A common mistake by amateur applicators is failure to keep a wet edge. Due to the short curing time of film forming sealers, it is imperative that the working area be kept wet and a proper feathering technique used. This is especially important in instances where a film forming sealer is used on a porous surface such as concrete with a brushed finish. Using a sprayer with a fan-tipped nozzle greatly improves results when combined with a sweeping and consistent feathering technique.
Concrete Appears Dark or Uneven in Color Post-Sealer Application
Acrylic sealers tend to darken concrete and impart a glossy, "wet look" finish, which can make the concrete's inherent color and texture variations more pronounced. Factors such as the concrete mix design, use of additives, finishing techniques, and porosity can influence the final appearance. To avoid unwanted color changes, opt for a penetrating water repellent sealer or conduct a small test area with a film-forming sealer to ensure the resulting color change is within acceptable limits.
