Gripset Xpress Primer H2O Plus Primer

To prevent waterproofing membranes and topical coatings from blistering or delaminating over damp or green concrete, Xpress Primer H2O Plus Primer forms a single-component vapour barrier that locks down residual substrate moisture. Unlike traditional epoxy vapour barriers, this water-resistant primer stops moisture without altering the surface profile, preserving the original texture of your screed, render, or concrete so overlaid finishes can achieve their intended mechanical bond.

How it works

Xpress Primer H2O Plus Primer is applied as a neat, single-coat liquid that penetrates mineral substrates. As it cures, it changes colour from milky white to a slight green tinge, finally drying completely clear to show it is ready for overcoating. This built-in visual indicator helps installers avoid premature membrane application, which can trap uncured moisture and lead to system failure. When used as a standalone sealer over screeds and renders, the primer blocks mineral migration to reduce efflorescence. On bare concrete, it seals the pores to prevent carbonation, protecting the reinforcing steel from structural degradation.

Where to use it

• Substrates: Concrete, green concrete, concrete block, screeds, renders, masonry, aerated concrete, compressed fibre cement sheeting, and plasterboard.
• Overlaid systems: Recommended for priming porous surfaces prior to applying Gripset Xpress Multi Pro Membrane, as well as other overlaid membranes and coatings.
• Sealing applications: Standalone sealing for concrete carbonation protection and efflorescence control on sand-cement screeds and mineral renders.

Numbers that matter

• 1 hour dry time: Fast-drying formula (at 23°C and 50% relative humidity) that allows you to apply waterproofing membranes or decorative finishes with minimal downtime on-site.
• 1 litre per 6m² coverage: A reliable application rate for estimating material requirements over standard mineral surfaces, though actual coverage varies with substrate porosity.
• 1-component formulation: Ready to use straight from the pail without measuring, mixing, or pot-life limitations associated with two-part epoxy barriers.

Limitations

• Suitable for use over concrete and mineral surfaces only.
• Do not apply to substrates subject to active, continuous sources of rising moisture or negative hydrostatic pressure; these must be treated with Gripset E60.
• Do not apply when surface or ambient temperatures are below 5°C or above 35°C.
• Do not apply when raining or when rain is imminent.

Application and preparation

All substrates must be clean, sound, smooth, and free of laitance, curing compounds, release agents, existing coatings, and general contaminants. High MPa concrete, burnished concrete, or steel-floated concrete surfaces that show no water absorption must be mechanically abraded or roughened to ensure the primer can penetrate the pores. Apply one coat neat by brush or medium nap roller until full coverage is achieved. Do not dilute. To prevent site dust or debris from contaminating the primed surface, install overlaid membranes or finishes shortly after the primer dries clear.