About Fosroc Nitoprime 28

Fosroc Nitoprime 28 is a two-component, solvent-containing epoxy primer engineered to be the bonding bridge between a prepared substrate and Fosroc’s epoxy repair and protection products. It is built on a modified epoxy resin base cured with a polyamide-amine hardener, the same resin chemistry family that gives epoxy systems their adhesion and chemical resistance. In a typical Indian repair sequence the primer is never the finished surface; it is the invisible interlayer that decides whether a heavy epoxy mortar will stay put on a soffit or peel away after a few monsoons.

The product earns its place where gravity is working against the repair. On vertical and overhead concrete – bridge soffits, basement walls, beam sides, the underside of cantilever slabs and the haunches of water tanks – a thick epoxy mortar such as Nitomortar HB has to grip the parent concrete with no help from gravity. Nitoprime 28 is formulated with high wetting-out characteristics so it penetrates the surface pores and microcracks of the prepared concrete, displacing air and creating a continuous mechanical and chemical key. Its deliberately long open time gives applicators a realistic window to prime an area and then return to lay the mortar or coating while the film is still receptive, which matters on large soffit areas where a fast-grabbing primer would force tiny, inefficient work patches.

Beyond concrete repair, Nitoprime 28 doubles as a metal primer, making it useful where exposed reinforcement, steel inserts or fixings sit inside the repair zone. It performs in both dry and submerged conditions once cured, which is why it appears in water-retaining and immersed applications alongside Fosroc’s epoxy coatings. It is genuinely solvent-borne, so it is flammable and must be kept away from ignition sources, used with ventilation, and cleaned from tools with Fosroc Solvent 102 immediately after use. One honest limitation defines its scope: it is not a damp-tolerant primer, so the substrate must be dry. For green or visibly wet concrete a different epoxy bonding aid is needed.

For Space Arc Engineering customers across Delhi NCR and Pan-India, Nitoprime 28 is best thought of as a system component, not a stand-alone purchase. Specify it together with the Fosroc topping it serves, plan the dry-substrate requirement into the programme, and it delivers reliable adhesion on exactly the orientations where repairs most often fail.

The technical insight

The performance of Nitoprime 28 comes from matching its cure chemistry and rheology to overhead work. The modified epoxy/polyamide-amine combination produces a tough, adherent film with good chemical and water resistance, while the polyamide-amine hardener contributes flexibility and tolerance to imperfect mixing ratios on site. Crucially, the cure is temperature-dependent: in cold conditions down to 5 degrees C the reaction slows and the open time extends, whereas at ambient temperatures above 35 degrees C – common on Indian sites from April to June – the pot life and tack window shorten noticeably. Applicators must therefore size their primed areas to the day’s temperature so the epoxy topping is still applied while the primer is tacky. The high wetting-out property is what lets a single thin film bridge to both porous concrete and non-porous steel, and the solvent carrier is the trade-off that delivers that low-viscosity penetration at the cost of flammability and the need for ventilation and a dry substrate.

Where it is used

• Priming vertical and overhead concrete before Nitomortar HB epoxy repair mortar
• Bonding primer ahead of Nitocote ET550 and other Fosroc epoxy protective coatings
• Priming exposed steel reinforcement, inserts and fixings within a repair zone
• Repair and lining of water-retaining structures and immersed concrete surfaces
• Bridge soffit, beam and column repairs where mortar must resist gravity
• Industrial floor edge, plinth and machine-base repairs using Fosroc epoxy compounds
• Basement, tank and tunnel concrete rehabilitation in dry-substrate conditions

Key advantages

• High wetting-out characteristics for deep penetration into concrete pores and a strong key
• Long open time gives a workable window to prime large overhead areas before topping
• Bonds equally to concrete and to metal, covering mixed substrates in one repair
• Performs in both dry and submerged conditions once cured
• Easily applied by brush or roller, needing no spray equipment
• Can be applied in cold conditions down to 5 degrees C
• Purpose-matched to Fosroc Nitomortar and Nitocote epoxy systems for a warrantable build-up

Limitations & considerations

• Not a damp-tolerant primer – the substrate must be dry, so green or wet concrete is excluded
• Solvent-based and flammable; requires ventilation and strict ignition control
• Pot life shortens at ambient temperatures above 35 degrees C, common on Indian summer sites
• Two-component product needing accurate on-site mixing of base and hardener
• Tools and equipment must be cleaned with Fosroc Solvent 102 immediately after use
• Functions as a system primer only; not a finished or stand-alone protective coating
• Overcoating must occur within the open time or the surface must be re-primed

Selection & best practice

Specifications

Industry use cases

How we position Fosroc Nitoprime 28

Nitoprime 28 sits within the Fosroc epoxy repair ecosystem as the dedicated solvent-based bonding primer for vertical and overhead work, paired most often with Nitomortar HB and the Nitocote ET550 coating. It should not be confused with the Nitoprime Zincrich range, which are anticorrosive zinc-rich primers for reinforcement steel rather than epoxy bonding primers – a different job entirely. Where the substrate is damp or green, a damp-tolerant epoxy bonding aid such as Fosroc Nitobond range or a Nitoprime variant suited to moisture should be specified instead. Against competitor systems, the closest alternatives are Sika’s epoxy bonding primers (e.g. Sikadur-32 family), MBS/MYK epoxy bonding agents, Dr. Fixit’s epoxy bonding primers, and STP epoxy bond coats; these are broadly comparable epoxy bridges, but the practical advantage of Nitoprime 28 is system compatibility – it is warranted to work with Fosroc’s own Nitomortar and Nitocote toppings, which simplifies specification and accountability. Space Arc Engineering, as an authorised Fosroc distributor in Delhi NCR and Pan-India, recommends buying Nitoprime 28 together with the Fosroc topping it serves so the full repair build-up is genuine and compatible.

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