About Fosroc Nitoprime 31

Fosroc Nitoprime 31 is the workhorse priming coat in the Fosroc resin-flooring family. It is a two-part, solvent-free epoxy primer based on an epoxy resin cured with an aromatic amine hardener, and its job is simple but critical: to convert a raw, porous, dusty concrete slab into a sound, sealed, chemically active surface that the Nitoflor resin floor can grip permanently. In Indian conditions, where in-situ concrete varies enormously in finish, laitance and moisture history, the primer is what makes or breaks the durability of the whole floor.

The product is supplied in pre-weighed two-pack units so the correct resin-to-hardener ratio is guaranteed on site – the smaller hardener pack is emptied into the larger base pack and mixed for two to three minutes with a slow-speed drill and paddle until uniform. Because it is solvent-free it is comparatively low-odour, will not trap solvent under a subsequent screed, and is well suited to enclosed industrial bays. Fosroc positions Nitoprime 31 specifically as the “normal weather conditions” primer in the range, meaning it offers a sensible working window before the topping has to go down, as opposed to the faster Nitoprime variants intended for rapid turnaround or cold conditions.

For a distributor-led project in Delhi NCR or anywhere across India, Nitoprime 31 is rarely specified on its own – it is almost always the first line item in a Nitoflor self-levelling or screed flooring specification. Space Arc Engineering supplies it as part of that complete system so that primer, body coat and seal coat all come from one manufacturer and carry a single warranty trail.

The technical insight

The defining chemistry here is the aromatic amine cure. Aromatic amine hardeners give the cured film excellent adhesion to mineral substrates and good chemical resistance, but they cure more slowly than aliphatic or modified amines – which is exactly why Fosroc markets Nitoprime 31 for normal weather and why its pot life is generous at low temperatures (5-7 hours at 5C) and short at high temperatures (about 30-60 minutes at 35C). On an Indian summer site that temperature sensitivity is the single most important thing to plan around: mixed primer left in the bucket at 40C ambient will gel far faster than the datasheet’s 25C figure of 1-2 hours, so it must be mixed in small batches and worked out quickly. Being solvent-free, the film cures by reaction rather than evaporation, so it does not shrink back into pinholes, and at roughly 0.3 kg/m2 it is intended as a thin penetrating seal coat rather than a build coat – the structural film thickness comes from the Nitoflor topping that follows, not from the primer itself.

Where it is used

• Priming concrete floors ahead of Fosroc Nitoflor self-levelling and screed resin flooring
• Sealing and dust-proofing dense, normal or porous concrete substrates
• First coat for selected epoxy and resin floor-coating systems
• Stabilising prepared slabs in factories, warehouses and process plants
• Priming concrete in food-processing, pharmaceutical and beverage facilities before hygienic resin floors
• Basement, plant-room and car-park floors receiving a resin build-up
• Repaired or screeded concrete surfaces requiring a bonded resin overlay

Key advantages

• Solvent-free formulation – low odour and suitable for enclosed industrial bays
• Pre-weighed two-pack units eliminate site mixing-ratio errors
• Penetrates and seals porous concrete, suppressing dust and pinholing
• Substantially improves adhesion of Nitoflor resin floors to the slab
• Generous pot life in cooler conditions allows controlled application
• Simple roller or brush application by general site labour
• Fully compatible with the wider Fosroc Nitoflor flooring system and single-source warranty
• Available in convenient 1 and 4 litre packs for small and large areas

Limitations & considerations

• Pot life shortens sharply in heat – usable life drops to roughly 30-60 minutes at 35C, demanding small batches on Indian summer sites
• Should not be applied below 5C, limiting cold-store and winter-night work
• Aromatic amine cure can amber/yellow on UV exposure, so it is intended for floors that will be over-coated, not as a decorative finish
• Requires a thoroughly prepared, sound, contamination-free substrate – it cannot fix weak or laitance-covered concrete
• Not a moisture-tolerant or damp-proof primer; high substrate moisture or rising damp needs a dedicated moisture-barrier primer instead
• Must be over-coated within the recommended window or the surface may need re-preparation
• 12-month shelf life and storage below 25C – hot, uncontrolled godown storage shortens usable life

Selection & best practice

Specifications

Industry use cases

How we position Fosroc Nitoprime 31

Within the Fosroc range, Nitoprime 31 is the standard general-purpose primer that pairs with the Nitoflor resin flooring family (such as Nitoflor self-levelling and screed toppings); choose a faster or specialised Nitoprime grade only when cold conditions, rapid turnaround or a specific substrate demands it, and use the zinc-rich Nitoprime Zincrich primers for rebar corrosion protection rather than flooring. Against competitors, it sits alongside Sika’s epoxy floor primers (e.g. Sikafloor-156/161), MBS/MYK Laticrete and BASF MasterTop priming resins, and Dr. Fixit/STP (Pidilite) industrial-floor primers – all broadly similar two-part epoxy seal coats. The honest differentiator is system integration and warranty: when the topping is Fosroc Nitoflor, using Fosroc Nitoprime 31 keeps the entire build-up single-source. For projects in Delhi NCR and Pan-India, Space Arc Engineering supplies Nitoprime 31 as part of the complete Fosroc flooring specification, with technical guidance on substrate preparation, moisture testing and the correct grade for the conditions.

Related Industrial Flooring products

View all Industrial Flooring products →