About Sika Sikafloor-290 Primer

Sikafloor-290 Primer is the foundation layer of a Sika epoxy floor system. Supplied as a two-part epoxy resin, it is the coat that goes down first onto prepared concrete, doing the unglamorous but decisive work of sealing an absorbent slab and creating a chemically active surface for the topping to grip. Concrete on its own is thirsty and dusty; left unprimed it draws resin out of the topcoat, traps air that later blisters, and never develops the bond strength the finished floor is quoted at. This primer solves all three problems in a single pass, which is why almost every Sikafloor epoxy build-up starts here.

What sets it apart on Indian sites is that it is solvent-free and effectively odourless, so it can be applied in enclosed halls, basements and occupied buildings where solvent-based primers would be a health and ventilation headache. It penetrates readily into highly absorbent surfaces, and once cured it hands over a consistent, well-keyed base to the Sikafloor-291 topcoat. For contractors, that translates into fewer bond failures, cleaner overcoating windows and a floor that performs to specification rather than to whatever the slab happened to allow.

The technical insight

The value of an epoxy primer lives at the interface you cannot see. A power-floated or ground concrete slab is a network of open capillaries and loose surface fines; a topcoat laid straight onto it bonds partly to dust and partly to trapped air. Sikafloor-290 Primer works because its low-viscosity, solvent-free resin wicks into those capillaries before it gels, then cures into the pore structure itself. The result is a mechanical anchor into the concrete plus a fresh, reactive epoxy skin on top that the following coat cross-links into chemically rather than merely sitting on. That two-way bond is what lets the system report tensile adhesion above 1.5 N/mm2 to ISO 4624 – in practice the concrete fails before the bond does. Because the resin is 100% solids, there is no solvent flashing off to leave voids or pinholes, so the sealed surface is genuinely continuous. The trade-off is that the chemistry is timing-sensitive: pot life is only around 45 minutes at 30 degrees C, and the overcoat window is defined at both ends, so the primer is engineered to be laid, watched and topcoated on a disciplined schedule, not left open.

Where it is used

• Priming new and hardened concrete floors before Sikafloor epoxy toppings and coatings
• Sealing highly absorbent or porous slabs that would otherwise starve the topcoat of resin
• Dust-binding of concrete in warehouses, workshops and storage areas
• Base preparation in industrial halls, production areas and dry-process facilities
• Priming in enclosed or poorly ventilated interiors and basements where solvent primers are unsuitable
• Providing the adhesion layer ahead of a Sikafloor-291 build-up coat
• Surface consolidation of weak, friable or dusting concrete surfaces
• Priming cementitious screeds before resin flooring systems

Key advantages

• Solvent-free and odourless, so it can be applied in occupied and unventilated spaces
• Penetrates deeply into highly absorbent substrates for a strong mechanical anchor
• Delivers tensile adhesion above 1.5 N/mm2 to ISO 4624 – typically the concrete fails first
• 100% solids formulation seals porosity without solvent voids or pinholes
• Simple 1:2.5 by weight mixing ratio with clearly colour-differentiated components
• Fast and easy roller or brush application at 0.20-0.40 kg/m2 per coat
• Good bond strength maintained across its full application temperature range
• Binds loose dust and consolidates weak surface layers in a single coat

Limitations & considerations

• Pot life is short – around 45 minutes at 30 degrees C – so only mix what can be used quickly
• Overcoating is time-bound: at +20 degrees C substrate, topcoat within roughly 6 to 48 hours
• Substrate moisture must be at or below 4% and the surface at least 3 degrees C above dew point
• Requires mechanical preparation (grinding or shot-blasting) and sound concrete of adequate strength
• Not a wearing surface or a standalone coating – it must be overcoated with a Sikafloor topping
• Highly porous slabs may need two coats, increasing consumption beyond the base figure

Selection & best practice

Specifications

Industry use cases

How we position Sika Sikafloor-290 Primer

Sikafloor-290 Primer is the entry point of a Sika epoxy floor system and is designed to run directly into a Sikafloor-291 build-up or the broader Sikafloor coating range, so it is best specified as part of a complete Sika build-up rather than in isolation. Where a slab is damp or a water-based primer is preferred, Sika’s own Ep-based primer options may suit better; where a self-smoothing or heavy-duty topping is planned, the primer stays the same and only the wearing layer changes. Across our other brands, contractors comparing options often look at MC-Bauchemie and Master Builders Solutions epoxy primers for equivalent industrial floor build-ups. As an authorised Sika distributor and applicator across Delhi NCR and pan-India, Space Arc can supply the full system and advise on the right primer-topcoat pairing for your substrate and service conditions.

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