Fosroc Nitozinc Primer Std
Two-component zinc-rich epoxy primer that gives exposed reinforcement and structural steel active galvanic protection against corrosion.
What is it?
A two-component anti-corrosive primer based on metallic zinc and epoxy resin that mixes to a grey liquid, giving exposed steel active ‘zinc-rich’ galvanic protection rather than just a barrier film.
Where is it used?
Applied on site to exposed steel reinforcement during concrete repair and to structural steel before topcoating, across bridges, buildings, water structures and industrial plants in India.
Why use it?
The sacrificial zinc protects steel electrochemically and prevents incipient (halo) anodes forming next to a patch repair, while remaining fully compatible with Fosroc Nitocote protective coatings and enamel topcoats.
How is it applied?
Steel is exposed, grit-blasted to bright metal and primed within 3 hours by brush in one or two unbroken 25-micron dry coats, then overcoated 30 minutes to 1 hour later.
About Fosroc Nitozinc Primer Std
Fosroc Nitozinc Primer Std is a two-component, zinc-rich epoxy primer engineered as the dedicated anti-corrosive coat for exposed steel reinforcement and structural steelwork. It is supplied as two parts based on metallic zinc and epoxy resin which, when mixed, give a grey-coloured liquid. The high loading of metallic zinc in the cured film makes the primer ‘active’ rather than merely a barrier: the zinc sits in electrical contact with the steel and corrodes preferentially, sacrificing itself to keep the underlying bar or section passive. In the Indian construction-chemicals market it is one of the most widely specified rebar primers in concrete repair systems, sitting alongside polymer-modified repair mortars and protective topcoats. Space Arc Engineering supplies Nitozinc Primer Std as an authorised Fosroc distributor across Delhi NCR and Pan-India, typically as part of a complete patch-repair or steel-protection package. A defining benefit is that it suppresses the formation of ‘incipient anodes’ (also called the halo or ring-anode effect) immediately adjacent to a completed repair. When a corroded zone of concrete is broken out and patched, the freshly repaired steel can become cathodic and push corrosion onto the still-chloride-contaminated steel just outside the patch. By galvanically protecting the cleaned bar, Nitozinc Primer Std reduces that risk and extends the durability of the repair. The primer is formulated for use with Fosroc Nitocote protective coatings and conventional enamel paints, so it integrates cleanly into a layered protection specification on Indian sites where reinforcement is exposed during rehabilitation or where structural steel needs corrosion priming before finishing.
The technical insight
The performance of Nitozinc Primer Std rests on galvanic (cathodic) protection rather than barrier action. Because zinc is more electronegative than iron, the zinc-rich film becomes the sacrificial anode and the steel the protected cathode; even at a small holiday or pinhole, surrounding zinc continues to protect the exposed steel, which is why the official Fosroc clause specifies that an unbroken 25-micron coating provides ‘active’ galvanic protection. The epoxy binder carries the metallic zinc particles and ensures they remain in electrical contact with both each other and the substrate while bonding tightly into surface pits and imperfections. This is fundamentally different from a passive primer that simply seals the steel; if a passive film is breached, corrosion proceeds, whereas zinc continues to cathodically protect a breached zinc-rich film. The specified low viscosity is deliberate, letting the coating penetrate into pits and micro-imperfections of grit-blasted steel where corrosion initiates. The trade-off is that galvanic performance depends on near-perfect surface preparation: the zinc must contact bright, clean steel, so the TDS insists on grit-blasting to a bright condition (with special attention to the back of exposed bars) and, where chloride-induced corrosion is present, high-pressure washing with clean water immediately after blasting to flush chlorides from pits. Application must follow within 3 hours of preparation so the cleaned steel does not re-rust before priming.
Where it is used
- Anti-corrosive priming of exposed steel reinforcement bars during concrete patch repair and rehabilitation
- Priming of structural steel sections before application of protective or enamel topcoats
- Preventing incipient (halo) anodes adjacent to completed concrete repairs in chloride-contaminated structures
- Corrosion protection of reinforcement in repair of bridges, flyovers and elevated road structures
- Reinforcement priming in water-retaining and marine structures such as tanks, reservoirs and coastal RCC
- Steel protection in industrial plants, factories and warehouses where rebar or steel is exposed during remedial work
- Use as the priming layer within a Fosroc Nitocote / Renderoc concrete repair specification
Key advantages
- Active zinc-rich system that protects steel electrochemically (galvanically), not merely as a barrier
- Suppresses incipient/halo anodes forming next to a finished patch repair
- Fully compatible with Fosroc Nitocote protective coatings and standard enamel paints
- Two-component, ready-to-use system that is straightforward to mix and brush apply
- Fast touch-dry of around 45 minutes at 20 degrees C, allowing overcoating within 30 minutes to 1 hour
- Low-viscosity film penetrates surface pits and imperfections in the steel
- Thin 25-micron dry film delivers galvanic protection without adding significant section thickness
- Protects primed steel under clean interior exposure for several months before overcoating
Limitations & considerations
- Galvanic performance is only as good as the surface prep: steel must be grit-blasted to bright metal
- Must be applied to dry, prepared steel within 3 hours of preparation, before re-rusting begins
- Minimum application temperature is 10 degrees C; must not be applied at 10 degrees C and falling
- Primed surfaces should not be left exposed indefinitely; max 14 days in non-aggressive exterior, less in marine/industrial
- Pot life is limited (about 3 hours at 20 degrees C, 2 hours at 35 degrees C), so only mix what can be used
- Shelf life is just 6 months in original unopened containers, shorter in heat/humidity
- It is an anti-corrosive primer, not a standalone finish; it needs a compatible protective topcoat for long-term exposure
- Contains resins, hardeners and solvents requiring ventilation and PPE; some users are sensitive to these
Selection & best practice
Expose all corroded steel fully and remove loose scale and corrosion deposits, then grit-blast to a bright condition, paying particular attention to the back of exposed bars. Where corrosion is chloride-induced, high-pressure wash with clean water immediately after blasting to flush chlorides from pits. Stir the primer thoroughly to redisperse settled zinc, then brush on one full, unbroken coat within 3 hours of preparation while the steel is dry; if an unbroken film is in doubt, apply a second coat once the first is fully dry (30 minutes to 1 hour). Overcoat with a compatible Fosroc Nitocote coating or enamel within the recommended interval, and minimise the time primed steel is left exposed in marine or industrial environments. Mix only what can be used within the pot life and clean tools with Nitoflor Sol immediately after use.
Specifications
| Product type | Two-component epoxy zinc-rich primer |
| Composition | Metallic zinc + epoxy resin |
| Mixed appearance | Grey coloured liquid |
| Specific gravity | 1.75 |
| Application (wet) thickness | 100 microns per coat |
| Dry film thickness | 25 microns per coat |
| Touch dry | 45 min at 20°C / 15 min at 35°C |
| Recoatable | 45 min to 1 hr at 20°C / 20-45 min at 35°C |
| Pot life | 3 hours at 20°C / 2 hours at 35°C |
| Coverage | 8.0 m²/litre/coat (theoretical) |
| Number of coats | One or two, depending on substrate profile |
| Min. application temperature | 10°C (not at 10°C and falling) |
| Max exposure before overcoating | 14 days (non-aggressive exterior); less in marine/industrial |
| Packaging | 20 litre pack |
| Cleaning solvent | Nitoflor Sol |
| Shelf life | 6 months (dry store, unopened) |
Industry use cases
Concrete Repair & Rehabilitation
Priming cleaned reinforcement during break-out-and-patch repairs so the new repair does not push corrosion onto adjacent chloride-contaminated steel (incipient anode control).
Bridges & Infrastructure
Anti-corrosive priming of exposed rebar on bridge soffits, piers and decks where carbonation and chloride ingress have corroded reinforcement.
Marine & Water-Retaining Structures
Galvanic priming of reinforcement in coastal RCC, tanks and reservoirs, with overcoating kept to a practical minimum due to the aggressive environment.
Structural Steel & Industrial
Corrosion priming of structural steel sections and exposed steel in plants and factories ahead of Nitocote or enamel topcoats.
Building Repair & Maintenance
Protecting exposed bars in spalled columns, beams and slabs of ageing residential and commercial buildings before reinstating cover with repair mortar.
Frequently asked questions
What is Fosroc Nitozinc Primer Std used for?
How does it protect steel from corrosion?
How many coats are needed and what is the dry film thickness?
What surface preparation does it require?
Can Nitozinc Primer Std be left exposed, or must it be overcoated?
How does it compare with other rebar primers like Sika or Dr. Fixit?
How we position Fosroc Nitozinc Primer Std
Nitozinc Primer Std sits in Fosroc’s corrosion-protection line as the active, zinc-rich choice for priming exposed reinforcement and structural steel, and it is most often specified as part of a wider Fosroc concrete-repair system (for example Renderoc repair mortars finished with Nitocote protective coatings). Its closest Fosroc sibling is Nitoprime Zincrich, also a zinc-rich epoxy primer; where galvanic protection is not essential, Fosroc’s epoxy or cementitious rebar primers can be used instead. Against the wider Indian market, it competes with rebar/steel primers from Sika (Sika MonoTop and Sika rebar primers), Dr. Fixit (Pidicrete rebar primers), MBS and STP (Shalimar/Zincanode-type and other corrosion-protective primers). The honest distinction is the protection mechanism: Nitozinc Primer Std and other zinc-rich primers deliver sacrificial galvanic protection and incipient-anode control, whereas many alternatives are barrier or polymer-modified cementitious primers. For high-chloride, marine or critical structural repairs the galvanic route is the stronger specification; for routine low-risk patching a barrier primer may be adequate and more economical. Space Arc Engineering, as an authorised Fosroc distributor in Delhi NCR and Pan-India, can advise on the right primer-and-topcoat combination for a given exposure class and budget.
Related Protective Coatings products
Source Fosroc Nitozinc Primer Std for your project
Authorised distribution, technical advice & professional application across Delhi NCR and Pan-India.