Unlike surface coatings, penetrating concrete sealers soak into the slab and chemically react within the pores. They provide long-term resistance to water, oil, and salt without forming a film or altering the floor's texture. These sealers are ideal for polished concrete, driveways, garages, or anywhere you want invisible protection with low maintenance. This guide explains how to properly apply a penetrating sealer to a concrete floor, from surface prep to final cure.
Before applying any sealer, the slab must be fully cured — usually 28 days from pour. If applied too early, moisture within the concrete may interfere with absorption. For older slabs, confirm that no moisture is migrating through the surface by performing a plastic sheet test or using a moisture meter. Never apply sealers to damp or sweating floors.
Remove dust, oil, curing agents, or previous coatings. Use a neutral pH cleaner or degreaser followed by a rinse with clean water. Avoid acidic cleaners unless the product manufacturer recommends it. If the slab is polished, clean using a fine pad and allow to dry fully. Surface pores must be open for the sealer to absorb — any residual barrier can prevent bonding.
Penetrating sealers can be applied with a low-pressure sprayer, roller, or soft-bristle broom. Sprayers offer the most even coverage, especially on large surfaces. Avoid high-pressure or atomising tips — they create overspray and waste. Always follow the product’s coverage rate and work in small, controlled sections. Apply in one continuous pass and avoid puddling or overlapping, which can cause dark patches.
Start at the far end of the slab and work backwards. Apply a liberal but even coat to saturate the surface. If using a roller, work in a crosshatch pattern to spread the material evenly. Do not apply more than one coat unless specified by the manufacturer. Most penetrating sealers only need a single application. Any excess should be removed with a dry microfibre cloth within 10 to 15 minutes.
Penetrating sealers typically dry within 1 to 4 hours, but chemical reaction and full cure may take 24 to 72 hours depending on humidity and temperature. Avoid foot traffic for the first 12 hours and keep the surface dry during curing. Do not allow rain or water contact within the first day. Some products recommend light burnishing after cure to close the surface, particularly on polished floors.
Many penetrating sealers last 5 to 15 years depending on the product and wear conditions. High-traffic areas like commercial floors or garages may require more frequent reapplication. Always clean the surface before recoating and test a small patch before full reapplication. Do not layer different types of sealer unless approved by the manufacturer.
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