About Fosroc Nitoprime 35

Fosroc Nitoprime 35 is a standard-cure, two-component, solvent-free epoxy primer engineered as the bonding link between a prepared substrate and a Fosroc Nitoflor epoxy flooring system. It is supplied as two pre-weighed components — a white liquid base and a yellow-to-dark-brown liquid hardener — that are blended on site and used immediately. Once mixed and rolled out, it penetrates the surface, seals the pores and forms a dense, continuous film that the following epoxy coating, self-levelling screed or trowel-applied topping keys into. Because it carries no solvent and is non-tainting, it suits hygiene-sensitive environments such as food, beverage and pharmaceutical floors where solvent odour and taint are unacceptable. For Space Arc Engineering’s customers in Delhi NCR and across India, Nitoprime 35 is a system component rather than a stand-alone product: it is specified whenever a Nitoflor epoxy build-up is being laid and the floor needs a reliable, repeatable adhesion base. Its appeal on Indian sites is practical — pre-weighed packs remove site batching errors, roller application means no costly equipment, and the solvent-free chemistry keeps it usable in enclosed plant areas with limited ventilation. The primer is the cheapest layer in an epoxy floor by material cost, yet it governs whether the whole system stays bonded; getting the primer right is the single most important step in avoiding delamination, blistering and premature failure of the finished floor. Nitoprime 35 is therefore best understood as low-cost insurance for a high-value flooring investment, and it should always be selected, applied and cured strictly in line with the Fosroc technical data sheet and the Nitoflor system it is priming.

The technical insight

Nitoprime 35 is a solvent-free epoxy, which is the technically important point — it builds the primer film from 100% reactive solids rather than relying on solvent that flashes off. On porous Indian concrete this matters because solvent-borne primers can leave voids and pinholes as the carrier evaporates, whereas a solvent-free film cures as a dense, impervious seal that blocks the subsequent epoxy from being drawn into the slab. The published tensile bond strength of at least 2 MPa, both in standard condition and after water immersion, typically exceeds the tensile strength of sound concrete itself, so a correctly primed floor fails in the concrete rather than at the bond line — the outcome you want. The practical discipline is moisture and timing. The TDS prohibits application above 75% relative humidity or on a substrate with rising moisture, and new concrete must be cured a minimum of 28 days (at 20°C) before priming, because trapped slab moisture is the most common cause of epoxy floor delamination on Indian projects. Cure data quoted at 25°C gives touch-dry in under 6 hours and hard-dry in under 8 hours, but those windows lengthen markedly in cool or humid conditions and the overcoating window must be respected — over-cured primer can glaze and lose its mechanical key. Substrate prep is non-negotiable: laitance must be removed by light grit-blasting, scabbling or grinding, and steel must be blast-cleaned to Sa 2½ and primed immediately before flash rusting begins.

Where it is used

• Priming concrete and cementitious screeds before Nitoflor epoxy self-levelling floors, coatings and toppings
• Sealing porous industrial concrete to prevent the subsequent epoxy being absorbed into the slab
• Priming blast-cleaned steel (to Sa 2.5) ahead of epoxy floor build-ups on steel decks and plates
• Adhesion base for hygienic, non-tainting epoxy floors in food, beverage and pharmaceutical plants
• Priming workshop, warehouse and light-to-medium industrial floors receiving epoxy wear coats
• Pre-treatment of prepared substrates where solvent odour must be avoided in enclosed areas

Key advantages

• Solvent-free and non-tainting — suitable for food and other hygiene-sensitive areas
• Excellent adhesion to concrete, cementitious screeds, the subsequent epoxy overlay and to steel
• Recommended, system-matched primer for the Fosroc Nitoflor epoxy flooring range
• Tensile bond strength of at least 2 MPa, retained after water immersion
• Simple roller or brush application — no specialist plant or spray equipment needed
• Supplied as pre-weighed two-component packs, eliminating site batching and ratio errors
• Fast cure at warm temperatures — touch-dry under 6 hours, hard-dry under 8 hours at 25°C
• 100% reactive solids form a dense, impervious sealing film over porous concrete

Limitations & considerations

• Cannot be applied below 5°C; substrate is best kept above 10°C for reliable cure
• Must not be applied above 75% relative humidity or where substrate moisture is rising
• New concrete must be cured a minimum of 28 days (at 20°C) before priming
• Requires thorough mechanical surface preparation — laitance, dust, oil and coatings must be removed
• Has a limited pot life once mixed and a finite overcoating window that must be respected
• Steel must be blast-cleaned to Sa 2.5 and primed immediately to avoid flash rusting
• Not a stand-alone coating or finish — it is only the primer layer of a Nitoflor system
• Uncured material can be cleaned with solvent, but once cured it can only be removed mechanically

Selection & best practice

Specifications

Industry use cases

How we position Fosroc Nitoprime 35

Within Fosroc’s own range, Nitoprime 35 sits alongside related epoxy floor primers such as Nitoprime 25 and Nitoprime 25(M) (general-purpose solvent-containing epoxy primers with good concrete penetration), Nitoprime 30 (epoxy primer that improves adhesion of epoxy toppings to damp substrates), Nitoprime 31 (a solvent-free aromatic-amine-cured Nitoflor primer) and Nitoprime SP (the recommended primer for the Nitoflor high-build range). The defining feature of Nitoprime 35 is that it is solvent-free and non-tainting, which makes it the preferred choice over solvent-borne primers like Nitoprime 25 in food, beverage and pharmaceutical areas, or in enclosed spaces with limited ventilation. It is purpose-matched to the Nitoflor family — Nitoflor SL3000 self-levelling epoxy, Nitoflor Hardtop wear toppings and similar build-ups — so specifying it keeps the whole floor inside one warranted Fosroc system. Against competitor primers, it competes with Sika’s epoxy floor primers (such as the Sikafloor priming range), MBCC/Master Builders Solutions MasterTop and MasterSeal primers, Dr. Fixit / Pidilite Roff epoxy floor primers, and STP/Sika India industrial flooring primers. Buyers should not select on primer price alone: the right choice is the primer validated for the specific topping, substrate condition and exposure, because a mismatched or wrongly applied primer compromises the entire floor regardless of brand. For Space Arc Engineering’s clients, the honest recommendation is to use Nitoprime 35 where a solvent-free, non-tainting Nitoflor primer is needed, and to confirm the exact primer-topping pairing against the current Fosroc system data sheet before ordering.

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