Prepare concrete by curing it fully (typically 28 days), removing laitance, form release oil, dust and efflorescence, repairing honeycombs and cracks, checking that moisture content is within the coating manufacturer's limit, and applying an appropriate primer.
The five checks
1. Age and cure: new concrete keeps releasing alkaline moisture; coating too early causes saponification and peeling.
2. Cleanliness: laitance and release agents create a weak boundary layer. Mechanical abrasion or acid etching removes it.
3. Soundness: tap-test for hollow areas and repair with a polymer-modified mortar.
4. Moisture: use a moisture meter, not a visual judgement.
5. Suction: a highly absorbent substrate pulls water out of the coating too fast and must be primed.
Priming choices
Penetrating clear primers stabilise chalky or porous surfaces. Pigmented bonding primers are used where the finish is thick or the substrate is dense and smooth, such as precast or shuttered concrete.
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Reviewed by
Sabbir Ahmed
Applications & Training Manager
Terraco-certified applicator trainer, 15 years site experience
See our technical advisory panelStandards referenced
- —EN 1504-10: Site application of products and quality control
- —Terraco technical datasheets and application manuals
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