AVOID PINHOLING
Stephen Boulton, Technical Service Manager at F. Ball and Co. Ltd., explains why pinholes occur in cured levelling compounds and what precautions contractors can take to stop this happening.
Following the application of a levelling compound, air, either from absorbent subfloors, such as concrete or sand/cement screeds, or trapped inside the levelling compound can form small air bubbles that burst upon reaching the surface of the levelling compound. Once the levelling compound has cured, these bubbles can leave tiny holes that look like pinholes or blisters, affecting the finished appearance of the flooring installation. Pinholing can also compromise its strength, potentially causing floor failure.
F. Ball recommends a few steps that contractors can follow to prevent pinholing.
PRIMING In almost all circumstances, it is essential to prime a subfloor before the application of a levelling compound, once it is established that the subfloor is suitably sound, smooth, dry and free of contamination.
Priming absorbent subfloors promotes the optimum performance properties of subsequently applied levelling compounds. It also stops moisture being drawn from the levelling compound by the absorbent subfloor, thereby preventing unacceptably rapid drying of the levelling compound. The primer creates a film across the surface of the subfloor that reduces the amount of air that can escape, which helps prevent pinholing.
F. Ball’s Stopgap P131 general-purpose primer is recommended for use over most absorbent subfloors, while its Stopgap P121 is specially formulated to promote the adhesion and application characteristics of compatible levelling compounds when applied over calcium sulphate screeds.
16 | TIP OF THE MONTH
Other precautions to avoid pinholing are aimed at preventing air being incorporated into the levelling compound or dispelling air trapped inside it.
MIXING To stop too much air being folded into the levelling compound when mixing, F. Ball recommends using a power whisk fitted to an electric drill to achieve a smooth, creamy and lump-free consistency. Mixing for around two minutes to prevent too much aeration is recommended.
SPIKED ROLLER After mixing and applying the levelling compound over the subfloor, F. Ball recommends rolling it with a long-handled spiked roller to get rid of any imperfections and trapped air. The spiked roller is designed to help easily eliminate air bubbles trapped within the compound and smooth out flow lines to achieve an optimum, uniform appearance and prevent pinholes occurring.
To avoid pinholing, it is important to carry out three important steps. Priming the subfloor prevents the levelling compound drying out too quickly and creates a film across the subfloor’s surface, stopping air from escaping. Secondly, mixing for the recommended two minutes stops too much aeration. Lastly, the use of a long-handled spiked roller over the total area of the levelling compound gets rid of any imperfections and trapped air.
www.f-ball.com/en
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