About Fosroc Nitoprime 30

Fosroc Nitoprime 30 sits at the start of almost every serious industrial floor build-up. It is a two-component epoxy primer, but the point that separates it from an ordinary sealer is its viscosity: it is deliberately thin, so instead of glazing over the concrete it wicks down into the pore network by capillary action. That means the resin cures inside the top few millimetres of the slab, not just across the face of it, and the finished primer becomes part of the substrate rather than a skin sitting on it. For contractors laying Nitoflor screeds and coatings, that penetration is what turns a dusty, thirsty slab into a stable, sealed platform.

The other reason specifiers reach for Nitoprime 30 is its tolerance of site reality. It is solvent-free, so there is no flammability or heavy odour to manage in an enclosed warehouse or basement, and it keeps working on substrates that are still damp, where a solvent-based primer would blush or fail to key. In practice that lets a flooring crew keep moving on a slab that is dry to touch but not bone-dry, without gambling the whole topping on it. Space Arc Engineering supplies it as an authorised Fosroc distributor and applicator across Delhi NCR and Pan-India, alongside the Nitoflor toppings and Renderoc repair mortars it is normally paired with.

The technical insight

The mechanism is mechanical interlock plus chemical bond, working together. Because the resin is low-viscosity, capillary action draws it into the concrete’s open pores before it gels; when it cures, those hardened resin threads anchor the primer layer into the slab like roots, which is far stronger than adhesion to a smooth troweled face. At the same time the epoxy chemically bonds to the mineral surface and, once the topping goes down while the primer is still receptive, cross-links into it so the whole build-up behaves as one system. The sealing action is what defeats outgassing: bare concrete is full of air-filled voids, and as ambient temperature rises that air expands and pushes up through a wet coating, leaving pinholes and craters. By filling and sealing those voids first, Nitoprime 30 removes the escape path, so the Nitoflor layer cures out flat and pinhole-free. Its damp-tolerance comes from a formulation that will still wet out and bond in the presence of residual surface moisture, rather than being displaced by it.

Where it is used

• Prime coat under Nitoflor epoxy and polyurethane floor toppings, screeds and self-levelling systems
• Sealing porous or dusty concrete slabs before a resin floor is laid
• Priming substrates that are dry to touch but still carry residual moisture
• Bonding coat ahead of Renderoc concrete repair mortars on prepared surfaces
• Dust-proofing and surface-hardening of weak or friable warehouse and storage floors
• Preparing floors in pharmaceutical, food-processing and manufacturing areas ahead of a hygienic topping
• Sealing basement and car-park slabs before protective floor coatings
• Consolidating the top layer of green or lightly laitance-affected concrete before overlay

Key advantages

• Low viscosity penetrates the concrete pore structure instead of merely coating the surface
• Works on damp substrates, so crews are not held hostage to a perfectly dry slab
• Solvent-free formulation means low odour and no flammability risk in enclosed spaces
• Seals voids to eliminate the outgassing pinholes that ruin epoxy and PU floor finishes
• Creates a strong, chemically bonded key between the concrete and the flooring topping
• Hardens and dust-proofs weak surfaces, improving the substrate before overlay
• Clear cured film makes it easy to see where full coverage has been achieved
• Backed by Fosroc technical support and Space Arc site guidance across India

Limitations & considerations

• It is a primer, not a moisture barrier — it tolerates damp but does not stop rising damp or hydrostatic pressure; a dedicated DPM is needed for wet-back slabs
• Epoxy pot life is short once mixed, so only prepare what the crew can apply within the working window
• Surface must still be mechanically prepared — grinding or shot-blasting and removal of laitance, oil and loose material — before priming
• The following topping should go down while the primer is still in its recoat window to get the best inter-coat bond
• Being epoxy, its exposed surface can chalk or discolour under UV, so it is a floor-build-up primer, not a finished exposed coat
• Low ambient temperatures slow the cure and can affect penetration on cold slabs

Selection & best practice

Specifications

Industry use cases

How we position Fosroc Nitoprime 30

Nitoprime 30 is the entry point to a Fosroc floor system, not a standalone product — position it with the topping it primes. It is normally specified directly under Nitoflor epoxy and polyurethane screeds and coatings, and as a bonding coat ahead of Renderoc repair mortars where the slab needs patching first. Within the Fosroc primer range, pair the recommendation against the substrate: Nitoprime 30 for porous or damp concrete, Nitoprime 25 for sound dry slabs, and the solvent-free Nitoprime SF or Nitoprime 31 where a specifier prefers those. For slabs with genuine moisture drive, cross-sell a Fosroc damp-proof membrane primer rather than relying on Nitoprime 30’s damp tolerance alone. Where a project is running another brand’s floor system, Space Arc also supplies comparable primers from MC-Bauchemie and Sika, so the recommendation can follow the topping the client has chosen.

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