Ensuring optimal adhesion and performance of SILCOR polyurethane-based waterproofing membranes requires a specialised primer. SILCOR Primer BS provides a strong physical bond and promotes adhesion to rigid substrates, even in cold weather. This prepares the surface, guaranteeing the membrane system performs as intended.

Why this product exists

SILCOR Primer BS was developed as a fast-drying, single-pack, modified polyurethane primer to prepare dry, rigid substrates with a maximum moisture content of 5% for all SILCOR polyurethane-based membranes. Its formulation delivers robust physical adhesion, crucial for the long-term integrity of the waterproofing system, especially on diverse construction surfaces.

The numbers that matter

• Drying Time: A tack-free time of just 30 to 60 minutes at 20°C allows for faster project completion. This rapid drying minimises weather-related delays and reduces the window of exposure for the prepared substrate.
• Coverage: An application rate of approximately 0.3 kg/m² ensures efficient material use. This consistent coverage contributes to uniform adhesion across the entire primed area, a critical factor for membrane performance.
• Substrate Moisture Limit: Suitable for substrates with a maximum moisture content of 5%. This specific threshold is a critical determinant for system selection, ensuring the primer bonds effectively without moisture-related failure.

What it's like to use

SILCOR Primer BS is applied directly from its container using a brush, roller, or spray. The treated surface must become tack-free before the SILCOR waterproofing membrane is applied. Strict adherence to the 24-hour recoat window is crucial; if the membrane is not applied within this timeframe, the primed area must first be wiped with Xylene, then lightly reprimed with SILCOR Primer BS once the Xylene has dried. If more than 72 hours pass without membrane application, the original primer must be fully removed by diamond grinding and the surface reprimed to ensure adequate adhesion.

Where this product excels

SILCOR Primer BS excels in critical waterproofing preparation for various rigid construction substrates. It is frequently specified in Roofing — concrete roofs, membrane-covered tiled projects as a primer for existing polyurethane membranes, ensuring renewed systems achieve their full bond strength. It is also used as a foundational primer for new or refurbished surfaces in Car parks, high traffic areas, and external above-ground structures, providing the necessary adhesion for trafficable waterproofing membranes.

How it fits in a real system

In applications such as an Elevated Walkway, SILCOR Primer BS functions as the essential first step. It is applied to the prepared substrate to establish a strong bond before the application of the primary waterproofing layer, such as SILCOR 580 trafficable waterproofing membrane. This foundational priming ensures the membrane system achieves its specified performance and durability.

Choose this when

• When preparing rigid substrates like concrete, masonry, cement render, compressed fibre cement sheet, or metal for any SILCOR polyurethane-based membrane.
• When the substrate has a maximum moisture content of 5%.
• When working in cooler ambient conditions where enhanced adhesion is required.
• When project timelines demand a fast-drying primer that provides temporary water resistance during application, protecting the structure from unexpected wet weather.
• When specifying primers for roofing or car park waterproofing systems.

Don't use this when

• Not for: Substrates with a moisture content exceeding 5%. For substrates with moisture content between 5% and 10%, consider SILCOR Primer BW Clear or EPOCOTE F100W Clear.
• Not for: Use as a standalone waterproofing layer or as a primer for non-SILCOR polyurethane membranes without explicit vendor approval.
• Not for: Surfaces that are not rigid or structurally unsound, as the primer relies on a stable substrate for effective bond.

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