Fosroc Nitocote ET402
Coal-tar extended, 100% solids epoxy protective coating for concrete exposed to seawater, effluent and aggressive chemicals.
What is it?
A two-pack, solvent-free coal-tar extended epoxy resin coating (100% solids) that forms an impermeable, chemical- and abrasion-resistant film on concrete and steel.
Where is it used?
Seawater tanks, channels and intakes, manhole and effluent linings, sewage and chemical-processing structures, jetties, piers and docks across coastal and industrial India.
Why use it?
It delivers long, low-cost service life with excellent resistance to acids, sewage and seawater, doubles as a waterproof barrier, and is a primerless high-build system that cuts coats and labour.
How is it applied?
Mix the two pre-weighed packs, then apply two coats by brush, roller or spray at 200 microns wet film per coat (5.0 m2/litre), overcoating after about 6 hours at 35 degrees C.
About Fosroc Nitocote ET402
Fosroc Nitocote ET402 is a protective coating engineered for the most aggressive wet and chemically loaded environments that concrete faces in India, from coastal seawater intakes to municipal sewage treatment plants. Chemically it is a coal-tar extended epoxy resin coating, supplied as a 100% solids, solvent-free two-pack material in pre-weighed quantities for accurate on-site mixing. The blend of an epoxy backbone with coal-tar pitch gives the cured film two complementary properties: the epoxy delivers hard, abrasion-resistant adhesion and chemical resistance, while the coal-tar component contributes water impermeability and resistance to constant immersion. Because it is 100% solids, the film thickness you apply is essentially the film thickness you keep after cure, with no solvent loss or shrinkage, which is why it builds reliably to high thicknesses on vertical and overhead surfaces. For Space Arc Engineering clients, ET402 sits in the corrosion-protection and tanking part of the Fosroc range, alongside epoxy primers, grouts and concrete-repair mortars. It is specified where a coating must survive years of immersion in seawater, raw sewage, dilute acids and alkalis without breaking down or supporting bacterial growth. The product is also available in a marine grade for the most demanding immersed marine service. Crucially for refurbishment work, ET402 can be applied to green (newly placed) concrete, which lets contractors protect young structures without the long drying delays that water-based systems demand. It is offered in convenient 10 litre packs, with Nitoprime 25 available as the recommended primer where a primer is used on more porous or contaminated substrates.
The technical insight
The defining technical trait of Nitocote ET402 is that it is a 100% solids, solvent-free coal-tar epoxy, which separates it from cheaper solvented bitumen or coal-tar paints. With no solvent to flash off, there is negligible film shrinkage, so a 200 micron wet film cures to effectively 200 micron dry film, and a two-coat system reliably delivers around 400 microns of continuous barrier. That high build, combined with negligible water absorption (less than 0.01% to ASTM D570) and nil water permeability at 2 bar over three months, is what makes it a genuine immersion-grade waterproofing coating rather than a surface sealer. Chemical resistance, tested to ASTM D543 over a 7-day soak at 23 degrees C, is rated excellent against 10% hydrochloric acid and 15% ammonia, and very good against 10% sulphuric, nitric and phosphoric acids, ferric chloride and raw sewage. Bond strength to concrete is a minimum of 1 N/mm2 (BS 1881 Part 207), it passes impact testing to BS 3900 Pt E3, and salt-spray testing showed nil failure at 200 microns over 1000 hours. The practical constraint engineers must respect is the short pot life once mixed: about 75 minutes at 25 degrees C, dropping to roughly 40 minutes at 40 degrees C, so mixed quantities must be planned to Indian summer conditions. Overcoating is permitted after about 6 hours at 35 degrees C (3 hours at 45 degrees C), with full cure in 4 days at 35 degrees C (BS 7542).
Where it is used
- Internal and external lining of seawater tanks, channels, sumps and intake structures at coastal and desalination plants
- Manhole, wet-well and effluent-channel linings in municipal and industrial sewage treatment works
- Protective coating to concrete in chemical-processing plants exposed to dilute acids, alkalis and ferric chloride
- Splash-zone and immersed protection of jetties, piers, docks and other marine concrete structures
- Waterproof barrier lining to water-retaining and below-ground concrete subject to constant or intermittent immersion
- Corrosion protection of concrete surfaces in fertiliser, dye and effluent industries where bacterial and chemical attack is a concern
Key advantages
- 100% solids, solvent-free formulation gives high film build with negligible shrinkage and no solvent loss on cure
- Excellent chemical and abrasion resistance and does not support bacterial growth, giving long, low-cost service life
- Acts as an impermeable waterproof coating in its own right (nil permeability at 2 bar, water absorption below 0.01%)
- Primerless on suitably prepared concrete, reducing the number of coats, materials and labour
- Can be applied to green concrete by brush, roller or spray, speeding up new-build protection schedules
- Supplied as pre-weighed two-pack units, removing site batching errors and ensuring correct mix ratio
- Available in a marine grade for the most aggressive immersed seawater service
Limitations & considerations
- Short pot life once mixed (about 75 minutes at 25 degrees C, around 40 minutes at 40 degrees C) demands disciplined, small-batch mixing in Indian summer heat
- Coal-tar pitch chemistry means the coating is supplied only in dark colours (black/brown), so it is a functional protective coating, not a decorative finish
- Coal-tar coatings carry handling, ventilation and PPE requirements, and are increasingly restricted for potable-water contact, so suitability for drinking-water tanks must be confirmed against current Fosroc data before specifying
- Requires thorough surface preparation, including removal of all laitance by grit blasting or equivalent, to achieve the rated bond
- Not intended as a structural or crack-bridging membrane; live or moving cracks need a dedicated flexible system
- Performance and pot life are temperature sensitive, so cold or very hot conditions need adjusted application planning
Selection & best practice
Achieve the published bond and chemical resistance by preparing concrete thoroughly first: remove all laitance, curing compounds and contamination by grit blasting or an equivalent mechanical method, then ensure the surface is sound and free of standing water. Apply Nitocote ET402 strictly as a two-coat system, building each coat to not less than 200 microns wet film and allowing the first coat to dry at least 6 hours at 35 degrees C (overcoat sooner only in hotter conditions) before the second. Mix only the quantity that can be used within the pot life, working in smaller batches during peak Indian summer temperatures to avoid waste; keep packs shaded and cool before mixing. Use Nitoprime 25 where the substrate is porous or marginal, and respect the 4-day full-cure period at 35 degrees C before exposing the lining to immersion or chemical service. Always mix in a well-ventilated area with the correct PPE, and store materials below 35 degrees C within the 12-month shelf life.
Specifications
| Chemical type | Coal-tar extended epoxy resin coating, 100% solids, solvent-free |
| Form / packaging | Two-pack (resin + hardener), pre-weighed; 10 litre packs |
| Colour | Black / Brown |
| Solids by weight (at 25 degrees C) | 100% |
| Specific gravity | approx. 1.54 at 20 degrees C |
| Coverage | 5.0 m2/litre at 200 microns wet film thickness (per coat) |
| Number of coats | 2 |
| Wet film thickness per coat | not less than 200 microns (approx. 400 microns total system) |
| Pot life | 75 minutes at 25 degrees C; 40 minutes at 40 degrees C |
| Tack-free time | 2 to 3 hours at 35 degrees C |
| Overcoating time | 6 hours at 35 degrees C; 3 hours at 45 degrees C |
| Full cure | 4 days at 35 degrees C (BS 7542) |
| Water absorption | <0.01% (ASTM D570) |
| Water permeability | Nil at 2 bar pressure over 3 months |
| Bond strength | Min. 1 N/mm2 (BS 1881 Pt 207) |
| Impact resistance | Passed (BS 3900 Pt E3) |
| Salt spray test | Nil at 200 microns over 1000 hours |
| Chemical resistance test | ASTM D543, 7-day soak at 23 degrees C |
| Recommended primer | Nitoprime 25 (flash point 55 degrees C) |
| Application methods | Brush, roller or spray |
| Shelf life / storage | 12 months stored below 35 degrees C |
Industry use cases
Marine & Ports
Lining of seawater intake tanks, channels and sumps, and protection of jetty, pier and dock concrete in the splash and immersion zones along India’s coastline, where ET402’s nil-permeability film and salt-spray performance resist chloride-driven corrosion.
Water & Wastewater
Coating manholes, wet wells, effluent channels and aeration-tank concrete in sewage and effluent treatment plants, where the coating resists raw sewage and does not support bacterial growth.
Chemical & Process Industry
Protecting bunds, trenches, tank pads and floor slabs exposed to dilute hydrochloric, sulphuric, nitric and phosphoric acids, ammonia and ferric chloride in chemical, fertiliser and dye plants.
Infrastructure & Tanking
Acting as a waterproof and corrosion-protective lining to below-ground and water-retaining concrete, including on green concrete during new construction to compress project schedules.
Frequently asked questions
Is Fosroc Nitocote ET402 a waterproofing coating or a corrosion coating?
How much Nitocote ET402 do I need and how thick should it be applied?
Does ET402 need a primer?
What is the pot life, and why does it matter so much in India?
Can ET402 be used inside potable (drinking) water tanks?
What surfaces can it be applied to, and can it go on new concrete?
How we position Fosroc Nitocote ET402
Within the Fosroc protective-coatings range, Nitocote ET402 is the heavy-duty coal-tar epoxy for immersed and chemically aggressive concrete, and it is typically specified alongside Nitoprime 25 primer and supported by Fosroc concrete-repair and grouting products such as the Renderoc and Conbextra ranges where substrate reinstatement is needed first. Where a non-coal-tar, lighter-coloured or potable-water-compatible lining is required, Fosroc’s own pure epoxy Nitocote systems become the more appropriate choice, and Space Arc can advise on the correct variant. Among competing brands available in India, credible alternatives include Sika’s Sikagard and Sikafloor coal-tar and epoxy protective coatings, MBS (MB Solutions) chemical-resistant epoxy linings, Dr. Fixit’s protective and tanking coatings from Pidilite for waterproofing-led applications, and STP (Shalimar Tar Products / STP Limited) coal-tar epoxy and bituminous coatings, which are long-established in marine and tanking work. ET402’s particular strengths in this field are its 100% solids high-build chemistry, its primerless application on prepared concrete, and Fosroc’s documented immersion, salt-spray and chemical-resistance data, which make it a strong specification choice where proven performance under constant seawater, sewage or chemical exposure is the priority. As an authorised Fosroc distributor and applicator serving Delhi NCR and Pan-India, Space Arc Engineering can supply ET402, recommend the right primer and complementary repair products, and advise on whether a coal-tar grade or an alternative epoxy lining best suits your exposure conditions.
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