Frequently Asked Questions

What surface preparation is required on a concrete floor slab before applying Fosroc Nitocote EP402 and what primer should be used under the coating?

The substrate preparation before Nitocote EP402 application is the same high standard required for all epoxy floor and surface coatings — and the quality of the preparation determines the adhesion and long-term durability of the coating more than any other factor. The surface preparation steps are: mechanical preparation — the concrete surface must be mechanically abraded to remove all laitance, curing compound, weak surface layer, contamination, and any existing coating; the preferred method is shot blasting for floor areas (most efficient, removes the largest volume of weak surface material quickly) or diamond grinding (for smaller areas or where shot blasting equipment cannot be used); surface profile — after shot blasting or grinding, the concrete surface must show a profile equivalent to CSP 3 to CSP 4 (ICRI surface profile scale) — this is a moderately rough profile that the eye can see clearly and that the finger can feel as distinct aggregate peaks, not a smooth, polished surface; contamination removal — in existing industrial floors where oil, chemical, or grease contamination has occurred, contamination must be removed before mechanical preparation: apply a degreaser (hot water and industrial alkaline degreaser), scrub into the surface, allow dwell time, and rinse thoroughly before mechanical blasting; if contamination has penetrated deeper than 5 to 10 mm into the concrete surface, the contaminated surface concrete must be ground away until a non-contaminated level is reached; priming — apply Nitoprime 30 (Fosroc two-component epoxy primer for concrete) to the prepared, clean, dry surface by roller; the primer penetrates the concrete pores, seals the surface, and provides the adhesion base for the Nitocote EP402 topcoat; allow the primer to cure to a tack-free film before applying EP402 — typically 4 to 8 hours at 25 degrees; check the primer surface for any pinholes or thin areas and apply a second primer coat if required before proceeding with EP402.

What is the difference between Fosroc Nitocote EP402 and Fosroc Nitocote SN1 and when is one recommended over the other for a chemical plant secondary bund lining?

Fosroc Nitocote EP402 and Fosroc Nitocote SN1 are both protective coating systems for chemical-resistant concrete surface protection, but they have different chemical compositions, chemical resistance profiles, and applications that make each the preferred solution in different environments. Nitocote EP402 is a solvent-free, two-component epoxy coating: strengths — excellent resistance to mineral oils, aliphatic hydrocarbons (petrol, diesel, lubricating oils), dilute acids (acetic, citric, phosphoric, sulphuric at low concentrations), dilute caustic (sodium hydroxide at moderate concentration), food-processing liquids, and cleaning chemicals; typically applied at 200 to 400 microns DFT as a smooth protective coating; very good adhesion to concrete; suitable for food contact surfaces in food processing (solvent-free, non-tainting); temperature resistance — good up to approximately 60 degrees under dry heat, lower under continuous hot water or steam exposure; limitations — aromatic hydrocarbons (benzene, toluene, xylene) cause swelling and softening; concentrated strong acids (fuming sulphuric acid, concentrated hydrochloric acid) degrade the epoxy binder. Nitocote SN1 is an epoxy-novolac-based or vinyl ester-based coating: strengths — significantly higher chemical resistance than standard epoxy; resists concentrated acids (sulphuric acid at moderate concentrations), strong oxidising acids, aromatic solvents, and a wider range of aggressive industrial chemicals; typically applied at higher DFT in a multi-coat system; suitable for the most demanding chemical environments; temperature resistance — higher heat and chemical combined resistance than standard epoxy. For a chemical plant secondary bund: if the contained chemicals are mineral oils, diesel, lubricating oils, dilute acids, and cleaning agents — Nitocote EP402 is adequate and more economical; if the bund must contain concentrated acids, aromatic solvents, or aggressive chemicals that attack standard epoxy — Nitocote SN1 provides the required higher chemical resistance. The Fosroc technical representative and a chemical resistance chart review specific to the bund chemicals are the correct starting point for any chemical containment lining specification.

How many square metres does 1 litre of Nitocote EP402 cover at the recommended DFT and what is the approximate coating quantity needed for a 200 square metre chemical bund floor and walls?

The theoretical coverage of Fosroc Nitocote EP402 at 200 microns DFT (the minimum recommended protective coating thickness — one full coat at the maximum roller application rate) is approximately 1,000 divided by 200 equals 5 square metres per litre theoretical coverage — but this is theoretical coverage and assumes zero waste, zero absorption, and a perfectly smooth surface. Practical site coverage is approximately 3 to 4 square metres per litre per coat, accounting for surface absorption by the concrete substrate (even a primed concrete surface absorbs some coating material into the surface pores), roller wastage (approximately 5 to 10 per cent of the material remains in the roller nap and on the roller tray), wastage from edges, corners, and detail work, and the need for a wet film thickness above the nominal 200 microns to achieve the DFT after film shrinkage on solvent release. A two-coat EP402 system (two coats of 200 microns each) at the practical coverage rate of 3.5 square metres per litre per coat: for 200 square metres of bund floor and walls: coat 1 — 200 divided by 3.5 equals approximately 57 litres; coat 2 — 200 divided by 3.5 equals approximately 57 litres; total EP402 — approximately 114 litres; add 10 per cent contingency — approximately 125 litres total. Primer (Nitoprime 30) coverage for 200 square metres at typical primer coverage of 4 to 5 square metres per litre: approximately 40 to 50 litres of primer. For an accurate material take-off for your specific bund project, the concrete surface porosity and condition must be assessed on site — a very porous concrete surface absorbs significantly more primer and first coat than a dense, well-prepared surface, and the site coverage rate must be calibrated with a trial area before committing to the full material quantity.