About Fosroc Nitoprime Zincrich Plus

Fosroc Nitoprime Zincrich Plus is the anti-corrosion primer that sits at the heart of almost every Fosroc concrete repair on a reinforced structure. When concrete spalls and the embedded steel is exposed, that steel is usually already corroding — either because carbonation has dropped the pH of the surrounding concrete or because chlorides (from sea air, de-icing salts or contaminated aggregate) have broken down the passive film on the bar. If you simply patch over rusty steel, the corrosion continues underneath the repair and blows it off within a few seasons. Nitoprime Zincrich Plus exists to stop that.

It is supplied as a single-component, grey-coloured liquid loaded with metallic zinc. Once brushed onto cleaned reinforcement, the zinc forms a film that is electrochemically more active than the steel. The zinc therefore corrodes preferentially (sacrificially) and supplies electrons to the steel, holding the bar in a protected, passive state. This is the same galvanic principle used in galvanised steel and sacrificial anodes, delivered here as a thin brush coat exactly where the repair engineer needs it.

For an Indian repair contractor, the appeal is practical. It is single-component, so there is no two-part mixing, no pot-life racing against the Indian afternoon heat, and almost no wasted material — you use what you need and reseal the tin. It dries to touch in about an hour at 20 degC, so a repair crew can prime in the morning and place Renderoc mortar the same shift. And because it is the Fosroc-approved primer for the Renderoc, Patchroc, Paveroc and Nitomortar repair families, you get a guaranteed-compatible system rather than mixing brands at the most critical interface. Space Arc Engineering supplies it as an authorised Fosroc distributor for projects across Delhi NCR and Pan-India, typically alongside the matching repair mortar and Fosroc Solvent 102 for cleaning.

The technical insight

The performance hinges on two often-overlooked details. First, the standard the TDS quotes is BS EN 1504-7, “Reinforcement corrosion protection” — specifically the coating must be applied as an unbroken 40-micron dry film to give continuous galvanic coverage. Pinholes or holidays break the electrical circuit and create local cells, so the back faces of exposed bars must be coated, which is why Fosroc recommends a small brush. Second, this is a galvanic (active/sacrificial) coating, not a barrier coating — it works because zinc is anodic to steel, not because it physically seals the bar. That distinction matters in chloride-contaminated repairs: high-pressure wash the steel with clean water after cleaning to flush chlorides from pits, because trapped chloride can drive corrosion even under a zinc primer. The product is also flammable (flash point 41 degC) and zinc-based, so it belongs to a different chemistry family than Fosroc’s two-part epoxy rebar primer, Nitoprime Zincrich (which combines zinc with epoxy). For purely passive carbonation-induced corrosion an epoxy-zinc primer is sometimes specified; for active galvanic protection within a repair patch, this single-component metallic-zinc version is the workhorse.

Where it is used

• Priming exposed, corroded reinforcement bars before patch repair with Renderoc, Patchroc, Paveroc or Nitomortar mortars
• Concrete repair on RCC buildings, columns and slabs suffering carbonation-induced spalling and rust staining
• Bridge, flyover and elevated-corridor soffit and pier repairs across highway and metro projects
• Marine and coastal structures (jetties, sea-facing facades, coastal plants) where chloride attack has corroded steel
• Water-retaining structures, STPs/ETPs, cooling towers and water tanks during rehabilitation
• Industrial floors, plant structures and parking decks where reinforcement is exposed during concrete repair
• Interior repairs needing several months of temporary steel protection before final overcoating

Key advantages

• Active zinc-rich galvanic system that combats corrosion electrochemically, not just as a barrier
• Single component — no mixing, no restrictive pot life, ideal for hot Indian site conditions
• Fast turnaround: touch dry in about 1 hour at 20 degC so repair mortar can follow the same shift
• Economical with almost no waste; reseal the tin and reuse
• Approved and fully compatible with Fosroc Renderoc, Patchroc, Paveroc and Nitomortar repair systems
• Compliant with BS EN 1504-7 reinforcement corrosion protection (method 11.1) and LU Standard 1-085 fire performance
• Low viscosity penetrates pits and imperfections on corrosion-damaged bars
• Protects steel under clean interior exposure for several months before overcoating

Limitations & considerations

• Flammable (flash point 41 degC) — keep away from ignition sources; not for hot-work-adjacent areas without precautions
• Minimum application temperature 5 degC; do not apply at 5 degC and falling or within 3 degC of dew point
• Requires steel cleaned to a minimum ST3 standard by mechanical means before application — surface prep is critical
• Must be applied to dry steel within 3 hours of preparation to avoid re-rusting
• Limited re-exposure window: max 14 days in non-aggressive exterior environments, far less in industrial/marine conditions, before overcoating
• Theoretical coverage of 8 m2/litre reduces in practice due to bar geometry and wastage
• Not a structural repair material on its own — it is a primer used within a full repair system
• Single component metallic-zinc chemistry differs from the epoxy-zinc Nitoprime Zincrich; specify the correct one for the job

Selection & best practice

Specifications

Industry use cases

How we position Fosroc Nitoprime Zincrich Plus

Nitoprime Zincrich Plus is positioned as the reinforcement primer step within a Fosroc concrete repair system rather than a standalone product — for best results it should be specified alongside the matching Fosroc repair mortar (Renderoc, Patchroc, Paveroc or Nitomortar) and Fosroc Solvent 102 for cleaning. Within the Fosroc range, the natural cross-link is to its sibling, the epoxy-based Fosroc Nitoprime Zincrich, and to the Renderoc repair mortar family that follows it. Against competitor systems, the closest equivalents are Sika’s MonoTop/Sika FerroGard zinc-rich and corrosion-inhibiting rebar primers, MBCC/Master Builders Solutions (formerly BASF) MasterEmaco P (e.g. P 727) zinc-rich primer, Dr. Fixit Pidicrete/rebar anti-corrosion primers, and STP (Pidilite group) reinforcement primers. The honest trade-off: Nitoprime Zincrich Plus is a single-component metallic-zinc galvanic primer — simpler and faster on site than two-part epoxy-zinc primers and ideal where the whole repair is being done in the Fosroc system, but for purely passive carbonation repairs where a robust barrier or epoxy bond coat is wanted, an epoxy-zinc primer (Fosroc’s own Nitoprime Zincrich, or a competitor’s epoxy product) may be specified instead. Space Arc Engineering, as an authorised Fosroc distributor in Delhi NCR and Pan-India, supplies the matched Fosroc system and can advise on the correct primer for the exposure condition and repair specification.

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