Fosroc Nitocote EPSW
A non-toxic, BS 6920-approved epoxy polysulphide high-build coating that protects potable water tanks, sewage works, silos and chemical-resistant floors with a flexible, seamless, crack-bridging film.
What is it?
A two-pack, non-toxic, high-gloss epoxy polysulphide protective coating that cures to a tough yet flexible seamless film, applied at 2 x 250 micron coats for a 500 micron total dry film thickness.
Where is it used?
Potable water reservoirs and tanks, intake channels and culverts, silos, sewage and sludge aeration/sedimentation tanks, food-processing and warehouse floors, and concrete or steel protective lining across India.
Why use it?
It is approved for contact with drinking water (BS 6920), resists a wide band of chemicals, oils, fuels and effluent, bridges cracks up to 2.5 mm, and bonds primerless to most sound substrates.
How is it applied?
Mix the pre-weighed two packs, then brush, roller or airless spray two 250 micron coats onto a prepared, dry substrate, recoating within 8 to 48 hours at 25 degrees C.
About Fosroc Nitocote EPSW
Fosroc Nitocote EPSW is a non-toxic, chemical-resistant epoxy polysulphide coating engineered for the harshest wet and contaminated environments a structure can face. Chemically, it marries epoxy resin with polysulphide, so it inherits the chemical resistance, hardness and adhesion of an epoxy while gaining the flexibility, elongation and crack-bridging behaviour of a polysulphide. The result is a high-gloss, high-build film that stays seamless and pinhole-free rather than cracking like a rigid, unmodified epoxy would under thermal movement or minor substrate cracking.
It is supplied as a two-component system, base plus hardener, in pre-weighed quantities ready for on-site mixing, which removes any guesswork on ratio for the applicator. The headline credential for Indian specifiers is its approval for contact with potable water under BS 6920, the British Standard for the suitability of non-metallic products for use with drinking water. That single fact makes it a default choice for lining municipal and private water reservoirs, overhead and underground tanks, and treatment-plant structures where leaching toxicity and taste/odour transfer are non-negotiable.
Beyond water retention, Nitocote EPSW is positioned by Fosroc as a dual-duty wall and floor coating. The same membrane that lines a clear-water tank can be specified to protect concrete and steel against sewage, sludge, sea water, oils, fuels and a long list of acids and alkalis, or laid as a hard-wearing seamless floor in confectionery units, food-processing halls, paper mills and warehouses. For Space Arc Engineering clients in Delhi NCR and across India, it sits squarely in the protective-coatings and corrosion-protection category as a single product that bridges potable, effluent and industrial-flooring duties.
The technical insight
The defining trait of Nitocote EPSW is its polysulphide modification. A standard high-build epoxy is hard and chemically tough but brittle, so any movement crack in the substrate telegraphs straight through the coating. By blending in polysulphide, Fosroc raises elongation to roughly 36 percent (ASTM D 412) and delivers crack-bridging capability of up to 2.5 mm, while keeping a Shore A hardness around 90 and tensile strength near 6 N/mm2. That combination is unusual: it behaves like an elastomeric membrane over hairline and minor static cracks, yet wears and resists chemicals more like a structural epoxy. Bond strength is reported as greater than the tensile strength of the concrete itself (ASTM D4541), meaning a correctly prepared substrate fails in the concrete, not at the coating interface. Designers should treat the 500 micron, two-coat system as the baseline specification because the published chemical-resistance and protective performance data are tied to that build at the stated 4 m2/litre coverage. Under-application to chase coverage is the single most common cause of premature failure. One practical caveat unique to this chemistry: the film must be kept off water for the first 24 hours, otherwise the curing surface can discolour, and like most epoxies it is not colour-stable under direct UV, which is cosmetic rather than structural but matters for exposed roofing work.
Where it is used
- Lining potable water reservoirs, overhead and underground tanks where BS 6920 drinking-water approval is mandatory
- Protective coating to intake channels, culverts and canals carrying raw or treated water
- Internal lining of silos and process tanks against chemical and abrasion attack
- Sewage and sludge aeration and sedimentation tanks at STPs and ETPs
- Corrosion-protective coating for structural and reinforced concrete and steel in aggressive environments
- Seamless, chemical-resistant flooring for confectioneries, food-processing units, paper mills and industrial warehouses
- Roofing and sub-structural waterproofing where a flexible, crack-bridging membrane is required
Key advantages
- Non-toxic and approved for contact with potable water under BS 6920
- Wide chemical resistance covering oils, fuels, sewage, dilute mineral acids, 50% caustic alkalis and sea water
- Flexible with crack-bridging ability up to 2.5 mm, unlike rigid unmodified epoxies
- Excellent abrasion and impact resistance suiting it to trafficked floors and effluent channels
- Primerless adhesion to most sound, dry concrete, with bond strength exceeding the concrete itself
- Single product serves potable, effluent, marine and industrial-flooring duties, simplifying procurement
- High-solids, low-odour formulation that minimises downtime in occupied or enclosed structures
- Applied by brush, roller or airless spray, allowing higher builds where needed
Limitations & considerations
- Not colour-stable under direct sunlight or contact with some chemicals, so the finish can chalk or discolour on exposed surfaces (cosmetic, not structural)
- Must be protected from contact with water for the first 24 hours after application or surface discolouration can occur
- Available only in standard blue and grey, limiting decorative or colour-coded options
- Not to be applied below 5 degrees C, at 5 degrees C and falling, or above 90 percent relative humidity
- Must never be thinned; Fosroc Solvent 102 is only for cleaning tools, not for dilution
- Porous, old or high water-cement-ratio concrete and all steel require priming (Nitoprime 31 or Nitoprime 28), so it is not truly universal primerless
- Pot life of around 80 minutes at 25 degrees C shortens in Indian summer heat, demanding disciplined batch sizing and crew planning
Selection & best practice
Specify and apply the full two-coat, 500 micron system; never thin the material. On concrete, ensure it is at least 28 days old or below 5 percent moisture, grit-blast or diamond-grind to remove laitance and open a key, and fill blowholes with Nitomortar TC2000. Prime porous or high w/c concrete with Nitoprime 31, and grit-blast steel to SA 2.5 then prime immediately with Nitoprime 28 before rust forms. Mix the entire hardener into the base with a Jiffy paddle on a slow drill for 3 to 5 minutes, then apply at once, scrubbing the first coat in to a uniform 250 microns and recoating within 8 to 48 hours at 25 degrees C. Size each mixed batch to the roughly 80-minute pot life, keep fresh film off water for the first 24 hours, and adopt hot-weather practices (shade, cool storage, avoid midday sun) above 35 degrees C, which is routine for much of the Indian working year.
Specifications
| Chemical type | Epoxy polysulphide based, two-pack (base + hardener) |
| Standards / approval | BS 6920 – approved for contact with potable water |
| Colours | Standard blue and grey |
| Recommended system | 2 coats x 250 microns = 500 microns total DFT |
| Coverage | 4 m2/litre per 250-micron coat (theoretical) |
| Pot life @ 25 deg C | 80 minutes |
| Recoat / overcoat interval @ 25 deg C | 8 to 48 hours |
| Tensile strength @ 7 days (ASTM D 412) | 6 N/mm2 |
| Elongation @ 7 days (ASTM D 412) | 36 % |
| Tear strength @ 7 days (ASTM D 1004) | 14 N/mm |
| Hardness @ 7 days (ASTM D 2240) | 90 Shore A |
| Crack-bridging ability | Up to 2.5 mm |
| Bond strength @ 7 days (ASTM D4541) | More than concrete (substrate fails first) |
| Abrasion resistance (ASTM D4060, CS-17, 500 g) | 80 mg @ 500 cycles; 110 mg @ 1000 cycles |
| Service temperature | -30 to 70 deg C |
| Flash point | > 65 deg C |
| Primers (if required) | Nitoprime 31 (porous concrete); Nitoprime 28 (steel) |
| Pack size | 4 and 20 litre packs |
| Shelf life | 12 months (5 to 30 deg C, dry, unopened) |
Industry use cases
Municipal & Building Water Supply
Internal lining of potable water reservoirs, sumps, overhead and underground RCC tanks where BS 6920 drinking-water approval and non-toxicity are mandatory before commissioning.
Water & Wastewater Treatment (STP/ETP)
Protective coating for sewage and sludge aeration and sedimentation tanks, and for intake channels and culverts, resisting effluent, dilute acids and biogenic attack.
Food, Beverage & Pharma
Seamless, non-toxic, easy-clean floor and wall coating for confectioneries, food-processing halls and paper mills where hygiene and chemical resistance are required.
Industrial & Warehousing
Abrasion- and impact-resistant flooring for warehouses and process areas, and chemical-resistant lining for silos and storage tanks holding oils, fuels and chemicals.
Marine & Coastal Infrastructure
Corrosion protection of concrete and steel exposed to sea water and splash zones, taking advantage of its sea-water resistance and flexible crack-bridging film.
Frequently asked questions
Is Fosroc Nitocote EPSW safe for drinking-water tanks?
What is the recommended thickness and coverage?
Does it need a primer?
How does it differ from a standard epoxy coating like Nitocote EP405?
What chemicals does it resist?
What are the pack sizes and shelf life?
How we position Fosroc Nitocote EPSW
Within the Fosroc range, Nitocote EPSW is the flexible, potable-water-approved member of the Nitocote protective-coating family. It is best understood alongside Nitocote EP405 and EP410 (solvent-free high-build epoxies for tougher chemical and floor duty on stable substrates), Nitocote EPS (an epoxy phenolic-type system) and Nitocote EPU (a UV-stable polyurethane top coat). A common Space Arc specification pairs EPSW with the wider Fosroc system: Nitomortar TC2000 to fill blowholes, Nitoprime 28 or Nitoprime 31 for steel and porous concrete, and Fosroc Solvent 102 for tool cleaning. Where colour stability under sunlight is needed, EPSW can be over-coated with a polyurethane finish such as Nitocote EPU. Against the wider Indian market, its closest credible alternative for drinking-water tanks is Sika’s Sikagard-62, which is likewise a two-component epoxy compliant with BS 6920; for flexible tank protection, Dr. Fixit TankPro W (a US FDA 175.300-certified polyurethane) and various MBS, STP Limited and other epoxy tank-lining systems compete on price and availability. EPSW’s distinctive selling point is that a single product covers potable, effluent, marine and industrial-flooring duties while remaining flexible enough to bridge cracks, which is why it remains a strong specification choice for water-utility, treatment-plant and food-industry projects across Delhi NCR and pan-India. As an authorised Fosroc distributor and applicator, Space Arc Engineering can supply EPSW, confirm chemical compatibility, and provide application support to ensure the warranted 500-micron system is achieved on site.
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