About Fosroc Nitoprime 25DS

Fosroc Nitoprime 25DS is the low-odour member of the well-known Nitoprime 25 family of epoxy primers. Like its parent product, it is a two-component (base plus hardener) epoxy primer engineered to wet out and penetrate concrete, leaving a thin, well-anchored film that the next coat of resin flooring, protective coating or repair mortar can grip. The defining difference is the “DS” formulation, which Fosroc markets as low odour — a meaningful advantage on projects where a conventional strong-solvent primer would be unpleasant or impractical to use, such as occupied buildings, kitchens, pharmaceutical areas, hospitals, retail spaces and poorly ventilated basements or plant rooms.\n\nA primer is not a decorative product, and it is easy to under-value its role. On bare concrete, an epoxy self-levelling floor or a protective coating applied directly to the slab can suffer from poor adhesion, pinholing and outgassing bubbles as air escapes from the porous substrate. Nitoprime 25DS exists to solve those problems: it soaks into the surface, blocks air release, binds residual fine dust, and presents a uniform resin-rich layer with consistent porosity so the topcoat cures and bonds predictably. In Fosroc’s flooring and protection systems it is therefore a system component rather than a stand-alone finish — it is almost always specified together with a named topping or coating.\n\nIn the Indian market, Nitoprime 25DS is most relevant on industrial-flooring contracts in Delhi NCR and across the country where the brief calls for a Fosroc Nitoflor or Nitocote build-up but the site cannot tolerate heavy primer odour. Typical settings include food and beverage units, dairies, pharma clean areas, hospital wings, commercial kitchens, basement car parks and warehouses being refurbished while partially occupied. As an authorised Fosroc distributor, Space Arc Engineering supplies Nitoprime 25DS alongside the matching Nitoflor toppings, Nitocote coatings and surface-prep ancillaries so that a single, compatible system is delivered rather than a mix of brands that may not be warranted together.\n\nIt is worth being clear about what Nitoprime 25DS is not. It is not a waterproofing membrane, not a moisture-vapour barrier for slabs with rising damp, and not a substitute for proper mechanical surface preparation. Its job is adhesion and sealing within an epoxy system, and it performs that job best when the concrete beneath it has been correctly prepared and is sound, clean and within the allowable moisture limits set out for the chosen topping.

The technical insight

The Nitoprime 25 family is a modified-epoxy, solvent-containing primer: the base resin is dissolved in solvent so it can flow into the capillary structure of concrete, then the solvent flashes off and the epoxy cures to a thin film keyed into the surface. The 25DS variant keeps that penetrating epoxy chemistry but reformulates toward low odour, reducing the harsh smell associated with conventional epoxy primer solvents. Practically, this changes site behaviour more than mechanical performance — pot life, mixing discipline and curing windows still govern the result. The parent Nitoprime 25 datasheet states a pot life of roughly 90 minutes at 20°C falling to about 30 minutes at 30°C, which is the single most important number on an Indian site: in Delhi NCR summer slab temperatures the working window shrinks sharply, so material must be mixed in small batches and applied immediately. Mixing is done by adding the full hardener tin to the base and blending for about 3 minutes with a slow-speed drill (400–500 rpm) and paddle until homogeneous; partial mixing causes soft, uncured patches. Coverage on the parent product is about 5.5–6.5 m2 per litre, varying with how porous and textured the slab is. A key technical feature is that the primer can be worked onto damp (not wet, not actively rising-damp) surfaces and that porous areas which “drink in” the primer and go matte should receive a second coat to seal them and prevent outgassing bubbles in the final epoxy layer. Recommended application temperature is 10°C to 40°C, with Fosroc to be consulted outside 5°C to 40°C. Because exact 25DS figures (specific gravity, VOC, recoat windows) are region- and pack-specific, the governing values for any given project must be taken from the current local Nitoprime 25DS TDS and the datasheet of the topcoat being used.

Where it is used

• Priming concrete before Fosroc Nitoflor SL self-levelling epoxy floor toppings
• Priming before Nitoflor TF (trowel-applied/heavy-duty) floor screeds
• Pre-treating concrete ahead of the Nitocote range of protective coatings
• Sealing the substrate before Nitomortar epoxy repair mortar patch repairs
• Pre-treatment under Nitoseal joint and gap sealants on concrete
• Sealing porous slabs to prevent pinholing and outgassing in epoxy floors
• Low-odour priming inside occupied or poorly ventilated spaces (kitchens, basements, plant rooms)
• Refurbishment flooring works in food, pharma, healthcare and retail environments where solvent smell must be minimised

Key advantages

• Low-odour epoxy formulation makes it usable in occupied, indoor and poorly ventilated areas where standard solvent primers are objectionable
• Good penetration into concrete, sealing the surface and binding residual fine dust
• Markedly improves adhesion of epoxy floor toppings, mortars and coatings to the slab
• Can be worked onto damp surfaces (where the substrate is otherwise sound and free of rising damp)
• Seals porous concrete to suppress air release and reduce bubbles/pinholes in the final epoxy layer
• Simple brush or roller application with straightforward mix-and-use field procedure
• Part of a single-source, warranted Fosroc system when paired with matching Nitoflor / Nitocote products
• Reasonable practical coverage on the parent grade (about 5.5-6.5 m2/litre) keeps primer cost a small fraction of the floor build-up

Limitations & considerations

• It is a primer, not a finish, waterproofing membrane or damp-proof barrier — it will not stop rising damp or moisture-vapour problems
• Short pot life in heat (about 30 minutes at 30°C on the parent grade) forces small batches and immediate use on Indian summer sites
• Performance depends entirely on correct mechanical surface preparation; it cannot rescue contaminated, weak or laitance-covered concrete
• Still solvent-containing — low odour reduces but does not eliminate the need for ventilation and standard PPE
• Must be overcoated within the correct window for the chosen topping; leave it too long or too tacky and adhesion suffers
• Only intended for use within Fosroc epoxy systems — not a general-purpose primer for unrelated coatings or substrates
• Application outside roughly 10-40°C requires Fosroc consultation, limiting unmanaged cold-weather or hot-deck use
• Exact 25DS numeric data (SG, VOC, recoat times) must be confirmed from the current local TDS rather than assumed from Nitoprime 25

Selection & best practice

Specifications

Industry use cases

How we position Fosroc Nitoprime 25DS

Nitoprime 25DS is the low-odour primer to specify when a Fosroc Nitoflor or Nitocote floor is being built in an occupied or poorly ventilated Indian interior. Within the Fosroc range it sits beside Nitoprime 25 / 25(M) (standard epoxy primers for the same systems) and is distinct from steel and rebar primers such as Nitoprime Zincrich and Nitozinc Primer, which protect metal rather than prime concrete. As a concrete primer it competes with Sika’s epoxy primers (e.g. Sikafloor primer grades), MBS (MYK/Saint-Gobain) and STP/Dr. Fixit epoxy floor primers; the practical reason to stay on Nitoprime 25DS is single-source system compatibility and warranty with the Fosroc topcoat above it, plus the low-odour benefit on sensitive sites. As an authorised Fosroc distributor, Space Arc Engineering supplies it as part of a complete, matched flooring system rather than as a loose primer.

Related Industrial Flooring products

View all Industrial Flooring products →