Fosroc Nitocote VF
Three-component solvent-free epoxy fairing putty that fills blow holes and levels minor imperfections so Nitoflor and Nitocote epoxy systems bond to a sound, closed surface.
What is it?
A thixotropic, solvent-free, three-component epoxy putty built from epoxy resins, graded fillers and thixotropic agents. It is the preparation coat that fills blow holes and makes good slightly damaged concrete before a decorative or protective epoxy system goes down.
Where is it used?
Concrete floors and walls that will receive Fosroc Nitoflor screeds or Nitocote coatings, typically in warehouses, pharma and food plants, workshops, basements and process areas where the finished coating must sit on a pinhole-free base.
Why use it?
Blow holes and pitting left unfilled bleed air into a fresh epoxy topcoat and cause pinholing, craters and higher coating consumption. Faring the surface first closes those voids, saves topcoat material and gives a smoother, more uniform finish.
How is it applied?
Base and hardener are power-mixed, then filler is added in stages to reach the working consistency. The putty is worked into holes and over irregularities with a trowel, scraper or filling knife, and left to cure before the epoxy topcoat is applied.
About Fosroc Nitocote VF
Nitocote VF is one of those unglamorous products that quietly decides whether an epoxy floor or wall coating looks right on handover. It is a three-component, solvent-free epoxy compound: a resin base, a hardener and a graded filler pack that also carries thixotropic agents. Mixed together they form a stiff, non-slump putty that can be pressed into blow holes, drawn across shallow pitting and used to make good slightly damaged concrete. Because it is a fairing and filling material rather than a coating in its own right, it is always applied ahead of a Fosroc epoxy system such as the Nitoflor floor range or the Nitocote wall and tank coatings.
The logic behind it is simple economics and appearance. Cast concrete almost never comes out with a perfectly closed face; entrapped air leaves blow holes, and formwork or wear leaves minor irregularities. Coat straight over that and the trapped air outgasses into the wet epoxy, leaving pinholes and craters that spoil the finish and, in chemical-exposure areas, become weak points. Nitocote VF lets the applicator close those defects with a material that is chemically compatible with the topcoat, cures without shrinkage and grips both concrete and steel. The result is a sound, level base that needs less topcoat and reads as a continuous surface rather than a patchy one.
The technical insight
The product works because it separates two jobs that a single coating cannot do well at once: bridging voids and delivering a thin, even film. A flowable epoxy coating is formulated to level out and stay thin, so it simply drapes over a blow hole and lets the air underneath escape upward. Nitocote VF is deliberately the opposite. Its thixotropic agents and heavy graded-filler loading make it non-slump, so it stays put on a vertical wall and can be trowelled hard into a hole where it displaces the trapped air instead of trapping it. Curing is a solvent-free epoxy reaction, so there is no evaporating carrier to leave shrinkage voids, and the cured putty reaches a compressive strength of about 50 N/mm2, close to good structural concrete, so the repair carries load rather than sitting as a soft plug. Because the consistency is set by how much filler you add, the same base and hardener can be dialled from a knife-grade skim for shallow imperfections to a stiff mortar-like mix for deeper holes, which is why one product covers a wide range of making-good on a single site.
Where it is used
- Filling blow holes and surface voids in cast concrete before an epoxy floor screed or coating
- Fairing minor irregularities and shallow pitting on concrete floors and walls
- Making good slightly damaged or spalled concrete faces prior to protective coating
- Preparing concrete substrates for Fosroc Nitoflor industrial floor systems
- Preparing walls and tank interiors for Fosroc Nitocote protective coatings
- Skimming formwork blemishes and honeycombing on exposed structural surfaces
- Sealing minor defects on steel and concrete before chemically resistant linings
- Reducing pinholing risk on floors that must meet a smooth, cleanable finish
Key advantages
- Non-slump and thixotropic, so it holds on vertical surfaces and trowels cleanly into blow holes
- Consistency is adjustable on site by varying filler content, from knife-grade skim to stiff mortar
- Solvent-free formulation, cures without shrinkage and leaves no evaporation voids
- High cured compressive strength of roughly 50 N/mm2 for a load-bearing repair
- Good adhesion to both concrete and steel substrates
- Cuts consumption of the subsequent epoxy topcoat by closing porosity first
- Chemically resistant, matching the exposure of the coatings it is paired with
- Available in a range of colours and easy to apply and finish with common tools
Limitations & considerations
- Not a stand-alone coating or waterproofing layer; it is a fairing and filling putty used under a topcoat
- Do not apply below 10 degrees C or above 40 degrees C; cured film is not suited to sub-zero service
- Short pot life of about 40 minutes at 25 degrees C, so mix only what can be placed in time
- Substrate must be clean, dry and free of laitance; sand blasting or mechanical brushing is often needed
- Deeper making-good or large repair areas are better handled by a dedicated repair mortar than by putty
Selection & best practice
Prepare first: concrete must be clean, dry and free of laitance, with mechanical wire brushing or light abrasive blasting where the surface is contaminated, and any steel blasted to SA 2 1/2. Mix the base and hardener under slow-speed power stirring, then add the graded filler in small increments until you reach a workable, non-slumping consistency; intermix thoroughly so there are no soft, under-catalysed pockets. Because pot life is only around 40 minutes at 25 degrees C, batch to what the crew can place in that window and take material to spot boards rather than working from the whole can. Trowel or knife the putty firmly into blow holes to expel air, then strike off flush. Allow it to reach the recoat window before the epoxy topcoat goes on, and clean tools immediately with Nitoflor Sol, as cured material can only be removed mechanically. Keep the working area between 10 and 40 degrees C throughout.
Specifications
| Product type | Three-component, solvent-free thixotropic epoxy putty |
| Density | 1.6 g/cc |
| Volume solids | 100% |
| Compressive strength | 50 N/mm2 |
| Pot life | 40 minutes at 25 degrees C |
| Drying time | 8 hours at 30 degrees C |
| Recoatable / full cure | 24 hours to recoat; full cure 7 days at 30 degrees C |
| Coverage | 1 m2 at 1 mm thickness per litre (varies with substrate) |
| Pack size / shelf life | 1/2 and 1 litre packs; 12 months unopened |
Industry use cases
Industrial and warehouse flooring
Fills blow holes across large cast slabs before Nitoflor screeds so the finished epoxy floor is smooth, pinhole-free and uses less topcoat.
Pharmaceutical and food processing
Closes surface voids on floors and walls that must be seamless and cleanable, removing the pitting where residue and bacteria would otherwise lodge.
Chemical plants and bunds
Fairs concrete and steel faces before chemically resistant Nitocote linings, giving the protective system a continuous, defect-free base.
Water and effluent structures
Makes good honeycombing and minor damage on tank and channel walls prior to a protective epoxy coating in aggressive exposure.
Workshops and process areas
Levels formwork blemishes and shallow irregularities so a durable epoxy finish reads as one continuous surface across the bay.
Frequently asked questions
Is Nitocote VF a coating or a waterproofing product?
How much Nitocote VF do I need?
How long do I have to work it once mixed?
What can it be top-coated with?
Can it be used on vertical walls and on steel?
What are the temperature limits?
How we position Fosroc Nitocote VF
Nitocote VF sits at the preparation stage of a Fosroc epoxy floor or wall build-up, so it is best specified alongside the topcoat it serves rather than on its own. On floors that means the Nitoflor range, and on walls, tanks and protective duties it pairs with the Nitocote coatings; keep Nitoflor Sol on hand as the tool cleaner. Where the making-good is larger than a blow-hole skim, or the substrate calls for a cementitious rather than resin repair, a dedicated fairing coat or repair mortar such as Fosroc Nitomortar FC is the more appropriate choice, and VF is reserved for the fine void filling immediately under the coating. Across our other brands, comparable epoxy fairing and repair putties are offered by Sika, Dr. Fixit and MC-Bauchemie, and our team can match a specification to whichever system the rest of the project is built around.
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