Fosroc Nitomortar FC
A two-component, solvent-free epoxy fairing coat that fills pinholes and surface irregularities to 3 mm, giving concrete a smooth, impermeable face ready for high-performance overcoating.
What is it?
A two-part, solvent-free thixotropic epoxy compound based on epoxy resins, graded fillers and performance additives, supplied as a grey trowel-grade paste.
Where is it used?
On concrete surfaces that must be made smooth and pinhole-free before Nitocote or Nitoflor coatings go down, plus general reprofiling, crack sealing and light-duty bedding work.
Why use it?
It seals blowholes and surface porosity so subsequent coatings apply evenly, without pinholing, cutting the number of coats needed and giving a durable, chemically resistant bond directly to concrete.
How is it applied?
Mix the full hardener into the full base with a slow-speed paddle, then trowel, scrape or squeegee onto clean dry concrete from a feather-edge up to 3 mm; no primer is required.
About Fosroc Nitomortar FC
Nitomortar FC is one of those products that quietly decides whether a protective-coating job succeeds or fails. Formed and repaired concrete is rarely as smooth as it looks. Blowholes, pinholes and shallow surface irregularities trap air, and when a thin-film epoxy or polyurethane coating is pulled across that texture it pinholes, holidays and thins out over the high spots. Nitomortar FC is Fosroc’s answer to that problem: a two-component, solvent-free, thixotropic epoxy fairing coat that fills those defects and hands the coating applicator a uniform, closed surface to work on. Because it is 100% solids and non-slump, it stays put on vertical and overhead faces and cures to a hard, impermeable skin.
For engineers and applicators in Delhi NCR and across India, the appeal is practical. It bonds straight to the concrete substrate without a separate primer, tolerates a wide range of site conditions, and resists the oils, fats, dilute acids, alkalis and solvents that industrial floors and process areas throw at it. It is best understood as a specification-grade surface-preparation material rather than a structural repair mortar. Anything deeper than 3 mm is not its job; for reprofiling and hole-filling beyond that depth Fosroc directs you to the higher-build Nitomortar FC(B). Used within its intended thickness, it is a fast, reliable way to turn rough concrete into a coatable surface, and it doubles as a general-purpose epoxy bedding mortar and adhesive when needed.
The technical insight
The performance comes from the chemistry, not from cement. Nitomortar FC is built on epoxy resins with graded fillers and performance additives, so when the base and hardener react they cross-link into a dense, void-free thermoset rather than hydrating like a cementitious mortar. That distinction matters on site. There is no water of hydration to bleed, no shrinkage cracking as it dries, and no laitance to abrade off before the next coat. The thixotropic, non-slump rheology lets it hold a build of up to 3 mm on vertical and overhead surfaces without formwork or sagging, then knock down smooth under a trowel or squeegee. Once cured it develops a compressive strength of 70 N/mm2 at 7 days and forms a completely impermeable film, which is exactly what a downstream protective coating needs: a stable, sealed, chemically inert base that will not outgas or telegraph substrate porosity through the finished system. Because it is 100% solids and solvent-free, there is no film shrinkage from solvent flash-off either, so the filled profile you trowel is the profile the coating sees.
Where it is used
- Filling pinholes and blowholes in concrete before overcoating with Nitocote or Nitoflor systems
- General reprofiling of concrete over large areas up to 3 mm depth
- Sealing surface cracks in preparation for resin crack injection
- Smoothing formed concrete faces in water-retaining structures ahead of protective coatings
- Preparing industrial floor and process-area concrete for chemically resistant epoxy toppings
- Fairing coat over basement, tank and containment walls before waterproof or lining coats
- General-purpose epoxy bedding mortar for setting fixtures and components
- Epoxy adhesive for bonding to concrete and similar rigid substrates
Key advantages
- Two-part, solvent-free 100% solids epoxy that cures without shrinkage or bleed
- Applies directly to concrete with no separate primer, saving a step on site
- Non-slump thixotropic paste holds up to 3 mm on vertical and overhead faces without formwork
- Reduces the number of finish coats needed by closing surface porosity in one pass
- Excellent chemical resistance to oils, fats, petrol, dilute acids, alkalis and solvents
- Reaches 70 N/mm2 compressive strength at 7 days and cures to an impermeable film
- Colour-coded, pre-weighed base and hardener packs for consistent site mixing
- Easy to trowel, scrape or squeegee and finishes to a smooth, coatable surface
Limitations & considerations
- Limited to a feather-edge up to 3 mm; use Nitomortar FC(B) for greater depths
- A surface-preparation and fairing product, not a structural or high-build repair mortar
- Must not be exposed to moving water during application, and heavy rain before final set can cause surface scour
- Part packs must never be used or part-mixed, as the base-to-hardener ratio is fixed
- Requires overcoats to be applied after the 24-hour cure, with the cured surface abraded and cleaned first
- Pot life is short, around 1 hour 40 minutes at 25 C and only 1 hour at 35 C, so mixed material must be used promptly
Selection & best practice
Start with a sound substrate: concrete must be clean, dry and free from laitance, and sandblasting or mechanical wire brushing is usually needed to open the surface. Mix a complete unit at a time. Stir the base and hardener separately to disperse settlement, empty the entire hardener into the base, and blend with a Fosroc paddle on a slow-speed 400 to 500 rpm heavy-duty drill until the colour and consistency are uniform; only 1 kg packs should be hand-mixed. Never use or blend part packs. Work quickly once mixed because pot life is roughly 1 hour 40 minutes at 25 C and drops to 1 hour at 35 C in Indian summer conditions. Apply from a feather-edge up to 3 mm with a trowel, filling knife or squeegee, keeping the material off moving water and protecting fresh work from rain until it sets. Allow the minimum 24-hour cure, then abrade the hardened surface and clean it dust-free before overcoating with epoxy systems. Clean tools with Fosroc Solvent 102 immediately after use; once hardened, the material can only be removed mechanically.
Specifications
| Product type | Two-component solvent-free thixotropic epoxy fairing coat / repair mortar / bedding and adhesive |
| Application thickness | Feather-edge up to 3 mm (use Nitomortar FC(B) above 3 mm) |
| Compressive strength | 70 N/mm2 at 7 days |
| Solids by weight | 100% at 25 C |
| Pot life | 1 hour 40 minutes at 25 C; 1 hour at 35 C |
| Drying time | 10 hours at 25 C; 4 hours at 35 C |
| Overcoating time | After a minimum 24-hour curing period |
| Colour | Grey |
| Coverage | Approx. 5 m2 per litre at 200 microns dft (surface dependent) |
Industry use cases
Industrial and warehouse flooring
Fair the concrete slab smooth and pinhole-free so chemically resistant Nitoflor epoxy floor toppings lay down evenly without holidays over process and traffic areas.
Water and wastewater structures
Close blowholes on formed tank, sump and reservoir walls before Nitocote protective linings are applied, giving the coating a sealed, impermeable base.
Basements and containment
Prepare rough shuttered concrete in basements, bunds and containment walls so waterproofing and chemical-resistant coats bond to a uniform surface.
Bridge and infrastructure repair
Seal surface cracks ahead of resin injection and reprofile shallow surface irregularities on structural concrete before protective overcoating.
Precast and architectural concrete
Fill pinholes and minor imperfections on formed and precast panels to deliver a smooth, coatable fair-faced finish.
Frequently asked questions
Is Nitomortar FC a cementitious repair mortar?
What is the maximum thickness I can apply in one pass?
Do I need a primer before applying it?
How soon can I overcoat it?
What is the pot life in Indian summer conditions?
What coverage should I plan for?
How we position Fosroc Nitomortar FC
Nitomortar FC sits at the surface-preparation end of the Fosroc concrete-repair and coatings system, and it is most useful when paired with the products that come before and after it. When a defect is deeper than 3 mm, step up to Nitomortar FC(B), the higher-build 3 to 5 mm epoxy sibling in the same family. Where a bond coat between old and new concrete is needed rather than a fairing coat, Nitobond EP is the two-part epoxy bonding agent to reach for. Once the surface is faired and cured, the intended finish coats are Fosroc’s protective systems, such as the epoxy novolac Nitocote EN901 for aggressive chemical exposure or the Nitoflor epoxy floor range for industrial slabs. If the real requirement is structural patch repair of spalled or carbonated concrete rather than surface fairing, a cementitious mortar like Renderoc HB is the honest choice instead. Across other brands we distribute, comparable epoxy fairing and blowhole fillers exist in the Sika and MC-Bauchemie ranges, and our team can specify the right one for your substrate, exposure and overcoat.
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