Bluestone, with its characteristic blue-grey hue and exceptional durability, is a popular choice for patios, walkways, and outdoor living areas. A question frequently asked by homeowners and DIY enthusiasts alike is whether it is possible to seal bluestone to enhance its performance and aesthetic appeal. The short answer is yes, sealing is not only possible but often highly recommended for maximizing the stone's longevity and ease of maintenance.
Why Seal Bluestone: The Core Benefits
Understanding the geological composition of bluestone, which is typically a hard sandstone or limestone, reveals why sealing is beneficial. While durable, the stone is naturally porous, acting like a sponge that can absorb liquids. This porosity makes it vulnerable to staining from common substances like coffee, oil, and rust, as well as damage from freeze-thaw cycles. Applying a high-quality penetrating sealer fills the microscopic pores, creating a hydrophobic barrier that repels water and stains without altering the natural texture or slip resistance of the surface.
Types of Sealers: Film-Forming vs. Penetrating
When learning how to seal bluestone, selecting the correct product is critical. There are two primary categories of sealers available, and choosing the wrong one can lead to suboptimal results or even damage. Film-forming sealers, also known as topical sealers, create a glossy or matte layer on the surface. While they offer high shine and enhanced color, they can become slippery when wet and may peel over time, requiring aggressive stripping and reapplication.
Penetrating sealers, often referred to as impregnators, are generally the superior choice for bluestone. These sealers soak deep into the stone to react with the minerals within, forming a water-repellent barrier internally. They maintain the natural, non-slip feel of the stone and do not yellow or wear away on the surface. For outdoor applications subject to weather and foot traffic, a penetrating silicone or acrylic sealer is the industry standard for protection.
Step-by-Step Application Process
Proper preparation is the most crucial step in the sealing process. Before applying any product, the bluestone must be thoroughly cleaned using a specialized stone cleaner to remove dirt, moss, and biological growth. Any existing old sealer must be completely removed with a stripping agent; applying a new sealer over an old one will cause bubbling and peeling. The stone must then be allowed to dry completely for a minimum of 48 to 72 hours, as sealing damp stone will trap moisture and cause failure.
Once the surface is bone dry and clean, apply the sealer using a low-lint roller or a sprayer designed for thin applications. Work in small sections to ensure even coverage, applying the sealer along the grain of the stone or following the natural joints. Avoid puddling or pooling, as this can lead to uneven curing. After the recommended dwell time specified by the manufacturer, wipe off any excess sealer from the surface to prevent hazing. A second coat is usually necessary for optimal protection and should be applied after the first has fully cured, which can take up to 24 hours.
Maintenance and Longevity
Sealing bluestone is not a one-time fix; it is part of a regular maintenance schedule. While a quality penetrating sealer can provide substantial protection for 12 to 36 months, its lifespan is directly affected by exposure to sunlight, weather severity, and the amount of foot traffic the area receives. Homeowners should monitor the surface for water beading; when the stone begins to absorb water and darken instantly upon contact, it is time to reapply the sealer. Routine cleaning with neutral pH detergents will prolong the life of the sealer and keep the bluestone looking vibrant.
By treating bluestone with the respect its composition deserves, sealing becomes a fundamental practice in preserving its beauty and structural integrity. The initial effort invested in selecting the right product and applying it correctly pays dividends by preventing costly repairs and stains down the line, ensuring the stone remains a stunning feature of the landscape for years to come.
