About Fosroc Nitoprime SP

Fosroc Nitoprime SP is the dedicated primer in the Fosroc Nitoflor epoxy flooring family. It is supplied as a two-pack, solvent-based epoxy that the applicator mixes on site in a simple 1:1 ratio and rolls, brushes or sprays onto prepared concrete before the high-build coating, screed or topping goes down. The product is engineered around one job: turning a raw, often dusty and porous concrete slab into a sound, sealed and chemically receptive surface so the expensive epoxy topcoat does not delaminate, blister or starve of resin.

In Indian conditions this matters a great deal. Freshly cast or older industrial slabs across Delhi NCR, the NCR industrial belts of Manesar, Bhiwadi and Greater Noida, and Pan-India sites are frequently laitance-covered, friable at the surface, and contaminated with construction dust. A topcoat applied directly to such a surface bonds only to the weak top layer and peels under traffic. Nitoprime SP solves this by penetrating deeply, binding loose particles into the resin matrix and hardening the surface zone, while simultaneously sealing the pores so that air pushed out of the concrete during topcoat cure cannot blow pinholes through the wet film.

Because it is solvent-based and low in viscosity, Nitoprime SP carries resin further into the capillary network than a thicker water-based primer would, which is why Fosroc positions it specifically for the Nitoflor epoxy range rather than as a universal primer. Space Arc Engineering supplies it as part of complete Fosroc epoxy flooring specifications, pairing it with the correct Nitoflor topcoat, Fosroc Solvent 102 for cleaning, and on-site application guidance so the whole floor system performs as one. It is a consumable, system-matched primer, not a standalone decorative product.

The technical insight

The performance logic of Nitoprime SP rests on viscosity and solids content working together. At roughly 30% volume solids and a mix specific gravity of about 1.0 g/cm3, the wet film is deliberately thin and resin-light so it can soak in rather than sit on top. The solvent carrier lowers viscosity further, letting the epoxy migrate into capillaries and micro-cracks where it cures to lock surface particles together, raise the substrate’s cohesive strength and block the path that capillary water and air would otherwise take. This is fundamentally different from a build primer or a barrier coat: the goal is impregnation and consolidation, not film thickness. The unusually long open time, 7 to 50 hours at 25C and 4 to 36 hours at 35C, is the second key feature. It gives a wide overcoating window so the Nitoflor topcoat can be applied once the primer has wetted in but before it has fully cured, which maximises chemical inter-coat adhesion between primer and topcoat. The single recommended coat (with a second only on very porous slabs) and the 1:1 mix ratio keep on-site dosing simple and reduce the risk of mix-ratio errors that plague three- and four-part systems.

Where it is used

• Priming concrete floors before Fosroc Nitoflor epoxy high-build coatings, screeds and self-levelling toppings
• Hardening and consolidating dusty, friable or laitance-affected industrial slabs
• Sealing porous cementitious screeds to prevent pinholing and blistering of the topcoat
• Reducing capillary water ingress into concrete and masonry by clogging surface pores
• Preventing surface contamination from blowing sand and loose deleterious material on factory and warehouse floors
• Surface preparation for epoxy flooring in pharmaceutical, food-processing and clean-room environments
• Priming substrates in basements, plant rooms, car parks and loading bays receiving epoxy systems

Key advantages

• Low viscosity gives deep penetration into the concrete pore structure for a strong mechanical and chemical key
• Hardens and stabilises weak, dusty surfaces, raising the substrate’s bond strength
• Long open time (up to 50 hours at 25C) provides a generous, forgiving overcoating window
• Simple 1:1 base-to-hardener mix ratio reduces on-site dosing errors
• Easy single-coat roller, brush or spray application
• Seals pores to cut pinholing and blistering of the subsequent epoxy topcoat
• Reduces capillary water ingress into the primed substrate
• Purpose-matched to the Fosroc Nitoflor epoxy flooring range for system compatibility
• Good economy at 8.00 m2/litre on typical sound concrete

Limitations & considerations

• Solvent-based and flammable (base flash point 24C, hardener 23C) – requires good ventilation and ignition control, limiting use in poorly ventilated or occupied spaces
• Strong solvent odour during application restricts use near food production in operation and in enclosed areas
• Must be applied to a sound, clean and dry substrate; it cannot rescue structurally weak or wet concrete or replace proper surface preparation
• Two-component product with a finite open time – mixed material must be used promptly and cannot be stored once activated
• Designed specifically for Fosroc epoxy/Nitoflor systems, not a universal or PU/water-based primer substitute
• Coverage of 8.00 m2/litre is nominal; very porous or rough slabs consume more and may need a second coat
• Hardened spills can only be removed mechanically; tools must be cleaned with Fosroc Solvent 102 immediately
• 12-month shelf life and below-25C storage requirement need managing in Indian summer warehouse conditions

Selection & best practice

Specifications

Industry use cases

How we position Fosroc Nitoprime SP

Nitoprime SP sits firmly inside the Fosroc Nitoflor epoxy flooring ecosystem as the solvent-based penetrating primer of choice. Within the Fosroc range itself it should be distinguished from other Nitoprime grades: Nitoprime 25 and Nitoprime 31 are alternative primers for different Fosroc systems, while Nitoprime Zincrich is an anti-corrosive primer for reinforcing steel in concrete repair – a completely different function. Where a low-odour or water-based primer is required, or the space cannot be ventilated, a water-based epoxy primer is the more appropriate Fosroc selection and Nitoprime SP is not the right choice. Against competitor systems, Nitoprime SP competes with Sika’s epoxy floor primers such as the Sikafloor primer range, with MBCC/Master Builders Solutions MasterTop primers, with Pidilite Dr. Fixit Newcoat-type floor preparation products, and with STP (Shalimar/STP) and other epoxy primer offerings. Its honest advantages are simplicity (1:1 mix, single coat), a long forgiving open time and deep penetration; its honest constraints are its solvent base, flammability and tight system match to Nitoflor. Space Arc Engineering’s recommendation is to specify the primer that belongs to the chosen topcoat family – for any Fosroc Nitoflor epoxy floor, Nitoprime SP is that primer – and to let our technical team match primer, topcoat and ancillaries rather than mixing brands across a single floor build-up.

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