Frequently Asked Questions

How does Nitoproof 100 compare to a surface coating or paint for protecting concrete and masonry from rain penetration?

Nitoproof 100 and a surface coating (paint, elastomeric coating, or silicone sealant coating) both provide water protection to concrete and masonry, but they do so by fundamentally different mechanisms with different performance characteristics and maintenance requirements. Nitoproof 100 penetrates into the substrate and forms an invisible hydrophobic treatment within the pore structure — the substrate retains its natural appearance, and the water repellency is due to the chemical surface energy change on the pore walls (water cannot wet or penetrate the hydrophobically treated pores). A surface coating forms a continuous film on the substrate surface that physically covers the pores and prevents water entry. The advantages of the Nitoproof 100 silane treatment approach are: no change to appearance (critical for heritage masonry, natural stone, and architectural concrete where a painted or coated finish would be unacceptable aesthetically); no risk of film delamination, blistering, or peeling (there is no film to delaminate); full vapour permeability (moisture vapour from the building interior or from residual substrate moisture can still pass through the treated substrate without causing blistering, which is the most common failure mode of surface coatings on imperfectly dry substrates); and low maintenance (no repainting cycle needed for the typical 10 to 15 year service life). The disadvantage compared to a film coating is that Nitoproof 100 does not bridge existing cracks — it treats sound concrete pores but cannot span a 1 mm crack, and for substrates with visible surface cracking, a flexible elastomeric coating is needed to bridge and seal the cracks.

Can Nitoproof 100 be applied to a wet concrete surface immediately after rainfall and how should the substrate be prepared before treatment?

Nitoproof 100 should not be applied to a wet or recently wetted concrete surface where free water is present on the surface or the pores are saturated with liquid water. The silane active ingredient in Nitoproof 100 penetrates the substrate by capillary transport — the driving force that pulls the silane solution into the pores is the same capillary suction that would normally pull water into the dry pores. When the pores are already filled with water from recent rainfall, there is no capillary suction available to drive the silane solution into the pores, and the product simply runs off the wet surface rather than penetrating. The substrate should be air-dried after rainfall — typically at least 24 to 48 hours of dry weather at 20 to 25 degrees Celsius to allow the surface zone of the concrete to dry sufficiently for silane penetration. In Indian hot summer weather (35 to 40 degrees Celsius), 12 to 24 hours after rainfall is usually adequate. The surface should not be bone dry — a very low moisture content in the pores is beneficial for silane treatments because the residual hydroxyl groups in the moist concrete facilitate the hydrolysis and bonding reaction of the silane. Substrate preparation requirements are minimal: the surface must be free of paint, grease, oil, or curing compound; friable laitance or loose surface material should be removed; and the concrete should not have active water leakage (standing water) on the surface.

How is Nitoproof 100 applied to a large concrete bridge deck and what is the typical site application procedure?

For large concrete bridge deck water repellent treatment with Nitoproof 100, the site application procedure involves the following steps. The bridge deck surface must first be confirmed to be dry, clean, and free of bituminous residue, tyre rubber deposits, oil, or existing surface coating — cleaning by power washing with water (then allowing full drying for 48 to 72 hours) and mechanical surface preparation by rotating wire brush or light grinding is typically required. The Nitoproof 100 is then applied by low-pressure airless spray, roller, or brush. For bridge deck treatment, low-pressure spray is the most efficient method for large areas — a pump-action garden sprayer, airless spray, or dedicated silane application equipment can be used, taking care to direct spray downward and to avoid drift onto vehicles, pedestrians, or water below the bridge. A single flood coat application is typically used, applying Nitoproof 100 at the specified coverage rate (4 to 8 square metres per litre, depending on the porosity of the concrete) and allowing the product to penetrate the surface until the surface-damp appearance dries off. A second application may be made on very porous concrete where the first application is fully absorbed within minutes — the second application should be made while the first coat is still visibly wet on the surface (wet-on-wet application). No overcoating or protection is required after application — the treatment is complete once the solvent or carrier has evaporated.