Fosroc Nitocote ET402E
High-build coal-tar-extended epoxy coating for long-term protection of concrete and steel in immersed, marine, effluent and chemically aggressive service.
What is it?
A solvent-free, two-pack epoxy resin coating modified with coal tar pitch, supplied in pre-weighed base and hardener packs for site mixing. It cures to a tough, impermeable black/brown film that resists water, sewage, seawater, dilute acids and alkalis.
Where is it used?
Seawater intake tanks, channels and culverts, manhole and sewer linings, effluent and sewage treatment works, chemical processing bunds, foundation and below-ground waterproofing, and steelwork on jetties, piers and docks across India.
Why use it?
It delivers excellent chemical and abrasion resistance plus a near-zero water permeability barrier from a primerless, two-coat system, lowering applied cost and whole-life maintenance on structures exposed to continuous wetting and aggressive media.
How is it applied?
Mechanically mix base and hardener for 3-5 minutes, then apply two coats by brush, roller or airless spray at 200 microns wet film per coat (about 180 microns DFT), overcoating after roughly 6 hours at 35 C onto grit-blasted, clean, laitance-free substrate.
About Fosroc Nitocote ET402E
Fosroc Nitocote ET402E is a coal-tar-extended epoxy protective coating engineered for structures that spend their working life in water, sewage, seawater or chemically loaded environments. It is the export/marine-grade member of Fosroc’s well-established Nitocote ET402 family, sharing the same solvent-free epoxy chemistry modified with coal tar pitch and supplied as a two-pack (base plus hardener) system in pre-weighed quantities for accurate on-site mixing. For Indian contractors and consultants this is one of the default specification choices wherever a durable, immersion-grade barrier is needed over concrete or steel.
The product is designed around three jobs at once: corrosion protection, chemical resistance and waterproofing. The cured film is impermeable, so it keeps aggressive water and dissolved salts away from reinforcement and away from the concrete matrix itself, while its dense crosslinked surface shrugs off the abrasion typical of flowing effluent, grit-laden seawater and tanked process liquids. Because it is a primerless system on properly prepared concrete, a full protective build can be achieved in two coats without a separate primer layer, which saves both material and a programme day on site.
Nitocote ET402E is positioned for seawater tanks, channels and intakes; manhole and sewer linings; sewage works and effluent plants; chemical processing areas; foundation waterproofing; and jetties, piers and docks. The marine grade additionally offers a biocidal, micro-biostatic effect so the coating does not support bacterial growth, which matters in sewage and standing-water assets where biofilm and microbially induced corrosion shorten service life. For Space Arc Engineering’s clients, the typical brief is a 25-50 year asset, exposed to continuous wetting, where a thin decorative paint will not survive and a heavy-duty, immersion-rated coal tar epoxy is the right answer.
It is worth being clear on chemistry. Coal-tar-extended epoxies remain widely specified in India for buried and immersed concrete and steel because of their cost-to-performance ratio and proven track record. They are black/brown only, are not recommended for warm potable-water contact, and in some export markets are being displaced by tar-free epoxies for health and aesthetic reasons. Where colour, food/potable contact or a non-coal-tar specification is required, a tar-free Fosroc grade or an epoxy from another reputable supplier should be considered instead, and Space Arc can advise on the right substitution.
The technical insight
The performance of Nitocote ET402E comes from a high-solids, solvent-free epoxy binder (about 90% solids by volume at 25 C, specific gravity around 1.54) crosslinked with an amine-type hardener and extended with coal tar pitch. The coal tar contributes hydrophobicity and chemical inertness cheaply, while the epoxy provides adhesion, hardness and crosslink density. The result, on the ET402 family, is independently notable barrier data: water permeability of 0.00 mm under 5 bar at 72 hours (BS EN 12390-8), water absorption below 0.01% (ASTM D570), and no corrosion in 1000-hour salt-spray testing at 200 microns. Bond strength to concrete is a minimum 1 N/mm2 (BS 1881 Pt 207), and curing efficiency is 93% to BS 7542, with the system also referenced to ASTM C309. For a designer, the practical takeaway is that two coats at the specified 200-micron WFT (about 180-micron DFT each, roughly 360-micron total dry build) form an essentially impermeable membrane, not merely a surface paint. The single biggest determinant of that performance is surface preparation: concrete must be grit-blasted to remove all laitance to an ACI 503R standard, and steel must be blast-cleaned to Sa 2.5 (Swedish Standard) bright metal. Pot life is the other site-critical parameter, around 75 minutes at 25 C dropping to about 40 minutes at 40 C, so in Indian summer conditions material must be mixed in workable batches and applied promptly.
Where it is used
- Lining of seawater intake tanks, channels, culverts and cooling-water structures at coastal and desalination plants
- Internal lining of precast and cast-in-situ manholes, wet wells and sewer segments against septic sewage and H2S-driven attack
- Protective coating to concrete in sewage treatment plants (STPs) and effluent treatment plants (ETPs) – tanks, launders and clarifier walls
- Chemical bund linings and secondary containment in process and fertiliser plants exposed to dilute acids, alkalis and oils
- Below-ground and foundation waterproofing where an immersion-grade, root- and chemical-resistant barrier is required
- Corrosion protection of grit-blasted steel and concrete on jetties, piers, docks and other marine splash-zone structures
Key advantages
- Primerless on properly prepared concrete – full protection in two coats, saving a coat of primer and programme time
- Excellent chemical and abrasion resistance against seawater, sewage, dilute acids, alkalis, oils and minerals
- Near-impermeable barrier – 0.00 mm water permeability at 5 bar and water absorption below 0.01%, protecting embedded steel
- Marine grade does not support bacterial growth, resisting biofilm and microbially induced corrosion in sewage assets
- High-build, solvent-free formulation (about 90% solids) with good hold-out on vertical surfaces, allowing thick coats per pass
- Versatile application by brush, roller or airless spray, and can be applied to green (young) concrete
- Compliant with recognised standards – BS 7542 and ASTM C309 curing efficiency, with documented salt-spray and permeability test data
Limitations & considerations
- Coal-tar-based and available only in black/brown – unsuitable where light colour, aesthetics or a tar-free specification is required
- Not recommended for warm or potable drinking-water contact; confirm a suitable WRAS/potable-grade alternative for such service
- Performance is highly dependent on surface preparation – concrete must be grit-blasted free of laitance, steel blast-cleaned to Sa 2.5
- Limited pot life, roughly 75 minutes at 25 C and about 40 minutes at 40 C, demanding small batches and prompt use in Indian summer heat
- Solvented/coal-tar vapours require open, well-ventilated working areas and proper PPE; not ideal for poorly ventilated confined spaces without controls
- Two coats with a 6-hour-plus overcoat interval at 35 C means the system is not a same-shift, single-application finish
- Coal-tar epoxies are being phased out in some export markets on health grounds, which can affect long-term spec acceptance
Selection & best practice
Specify and apply by the datasheet, not by eye. On concrete, remove all laitance by grit blasting to an ACI 503R standard and fill blowholes and irregularities with a Fosroc Nitomortar FC repair filler before coating; on steel, blast to Sa 2.5 bright metal and coat immediately, priming with Nitoprime 25 only if a rust bloom cannot be avoided. Mix the entire hardener and base cans together with a slow-speed drill and paddle for 3-5 minutes until uniform – never split packs by hand, as the pre-weighed ratio is fixed. Mix only what can be used inside the pot life (about 75 minutes at 25 C, less when hot), and apply the first coat at not less than 200 microns WFT, allowing at least 6 hours at 35 C before the second coat, which must follow within roughly 4 days. Use a wet-film comb to verify build, work in open, well-ventilated conditions with appropriate respiratory PPE, clean tools immediately with Nitoflor Sol, and protect the green coating from rain and traffic until cured (full cure around 4 days at 35 C). Always confirm batch-specific values against the current local Fosroc TDS, since regional formulations vary.
Specifications
| Product type / chemistry | Two-pack solvent-free epoxy resin modified with coal tar pitch (coal-tar-extended epoxy) |
| Colour | Black / Brown |
| Solids by volume @ 25 C | 90% |
| Specific gravity | 1.54 at 27 C |
| Number of coats | 2 (minimum) |
| Wet film thickness per coat | 200 microns |
| Dry film thickness per coat | 180 microns |
| Pot life | 75 minutes at 25 C; 40 minutes at 40 C |
| Tack-free time | 2 to 3 hours at 35 C |
| Overcoating time | 6 hours at 35 C; 3 hours at 45 C |
| Full cure | 4 days at 35 C |
| Curing efficiency (BS 7542) | 93% |
| Water absorption (ASTM D570) | <0.01% |
| Water permeability @ 5 bar, 72 hrs (BS EN 12390-8) | 0.00 mm |
| Bond strength (BS 1881 Pt 207) | Min 1 N/mm2 |
| Salt spray (BS 1881 Pt 124, 1000 hrs) | Nil corrosion @ 200 microns |
| Chemical resistance reference | ASTM D543 (7-day immersion at 23 C) |
| Standards referenced | BS 7542, ASTM C309, ASTM D570, ASTM D543, BS EN 12390-8, BS 1881 |
| Application methods | Brush, roller or airless spray |
| Concrete surface prep | Grit blast to remove laitance, ACI 503R-89 Ch.5 Para 5.4 |
| Steel surface prep | Grit blast to Sa 2.5 (Swedish Standard) bright finish |
| Primer | Not required on prepared concrete; Nitoprime 25 on steel if needed |
Industry use cases
Water & Wastewater (STP/ETP)
Lining of clarifier walls, aeration tanks, wet wells and sewer manholes in municipal and industrial treatment plants, where the impermeable, micro-biostatic film resists raw sewage, H2S attack and continuous immersion.
Marine & Ports
Coating of grit-blasted concrete and steel on jetties, piers, docks, seawater intakes and cooling-water channels, exploiting the 1000-hour salt-spray and zero-permeability performance against seawater and splash-zone wetting.
Chemical & Process Industry
Bund and secondary-containment linings, plinths and floors exposed to dilute hydrochloric, sulphuric, nitric and phosphoric acids, caustic soda, ammonia, oils and ferric chloride, where ASTM D543 immersion data supports the chemistry.
Infrastructure & Foundations
Below-ground waterproofing of foundations, basements, pile caps and buried concrete needing a tough, root- and chemical-resistant barrier that protects reinforcement from chloride and moisture ingress.
Power & Desalination
Protection of seawater and cooling-water structures, channels and tanks at coastal thermal, desalination and industrial plants subject to abrasive, saline flow.
Frequently asked questions
Is Nitocote ET402E a genuine Fosroc product?
What is Nitocote ET402E made of and what does it do?
How many coats and what thickness should be applied?
Does it need a primer?
Can Nitocote ET402E be used for potable drinking-water tanks?
What is the pot life and how does Indian heat affect it?
How we position Fosroc Nitocote ET402E
Within Fosroc’s range, Nitocote ET402E sits at the heavy-duty, immersion-grade end of protective coatings, alongside its parent grade Nitocote ET402 and related corrosion products such as the Nitoprime primer range and Nitomortar FC repair mortars used to prepare and fair the substrate before coating; for above-ground or coloured chemical-resistant duty a Fosroc tar-free or pure-epoxy floor/wall coating is the better fit, and for crack-bridging deck waterproofing the Nitocote and Proofex membranes apply. Specifiers commonly cross-reference it against Sika’s coal-tar and tar-free epoxy coatings (the Sikagard and Sikafloor families), MBCC/Master Builders Solutions (MBS) Masterseal and Mastertop systems, Dr. Fixit’s industrial epoxy and tar-epoxy coatings for sewage and marine work, and STP Limited’s coal-tar and epoxy protective products – all of which offer broadly comparable immersion-grade performance, so selection in India usually turns on local Fosroc TDS values, distributor support and applicator availability rather than chemistry alone. Space Arc Engineering’s role is to confirm the right grade for the actual exposure, supply genuine Fosroc material, and back it with authorised application across Delhi NCR and Pan-India; where a coal-tar coating is not acceptable on health, colour or potable-contact grounds, we will recommend and supply a suitable tar-free alternative.
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