Mapesil AC Silicone Sealant

Achieving a durable, mould-resistant, and highly elastic seal for expansion joints and critical wet areas prevents common failures. Mapesil AC provides that confidence, offering a pure acetic silicone sealant engineered for challenging environments like sanitary ware, swimming pools, and glazing, where longevity and cleanliness matter most.

Why this product exists

Mapesil AC was developed to provide a pure, mould-resistant, and highly elastic acetic-crosslinking silicone sealant. It addresses the need for durable and adaptable seals for expansion joints and elastic gasketing. It offers robust performance in environments requiring resistance to climatic extremes, chemical agents, and mildew, especially on glass, ceramic, and anodised aluminium substrates.

The numbers that matter

With a maximum movement allowance of ±25%, Mapesil AC ensures joints can accommodate significant structural shifts without compromising the seal. This is crucial for expansion joints in diverse building materials, preventing premature failure and callbacks. An elongation at break of 800% provides a substantial safety margin against stretching, far exceeding typical joint movements and resisting extreme loads. This ensures the sealant remains intact even under unexpected stress.

Its wide temperature resistance from –40°C to +180°C means it maintains integrity across Australian climatic extremes, from freezing winters to scorching summers. This makes it suitable for both interior and exterior applications where temperature fluctuations are common. A Shore-A-Hardness of 20 offers a flexible, pliant seal that can absorb dynamic stresses. It remains durable enough for its intended use without becoming brittle, critical for long-term performance.

What it's like to use

Preparation is key for optimal performance. All surfaces must be dry, solid, and thoroughly cleaned, free from dust, oils, and old residues. For substrates like concrete, timber, metals, painted surfaces, plastics, and rubber, adhesion is greatly enhanced by pre-treating the joint with Primer FD. Apply Primer FD with a small brush and allow a few minutes for the solvent to evaporate before applying Mapesil AC.

To control the sealant depth and prevent three-sided adhesion, use a Mapefoam polyethylene cord to fill the base of the joint. Once applied, extrude Mapesil AC from the cartridge smoothly. Finish the surface with a tool moistened with soapy water before a skin forms. Unpolymerised sealant can be cleaned with common solvents, while cured silicone requires mechanical removal.

Where this product excels

• Wet Areas: Sealing joints around sanitary ware and ceramic tiles in kitchens, bathrooms, and showers, ensuring mould-free longevity and a hygienic finish.
• Glazing: Forming elastic seals for glazing, door, and window frames, portholes, and glass assemblies where high movement and UV stability are required.
• Swimming Pools: Sealing expansion joints in swimming pools, enduring continuous water immersion and resistance to pool chemicals without degradation.
• Industrial Applications: Gasketing and sealing in industrial environments like tanks, pipes, and areas subject to high chemical or thermal stress, leveraging its wide temperature resistance.

How it fits in a real system

Mapesil AC is typically applied as the final sealing component within a construction system. In tiled wet areas, it forms the critical elastic and waterproof barrier at movement joints, complementing a primary waterproofing membrane beneath the tiles. In glazing systems, it acts as the primary sealant for glass and frame interfaces. For optimal adhesion to a broad range of porous and non-porous substrates beyond glass, ceramic, and anodised aluminium, the use of Primer FD is specified. Correct joint sizing and the inclusion of a Mapefoam backer rod are essential to ensure the sealant can move freely and perform its function.

Choose this when

• When you need a highly elastic sealant (±25% movement) for expansion joints or gasketing.
• When sealing around sanitary ware, ceramic tiles, or in swimming pools where mould resistance is critical.
• When working with glass, ceramic, or anodised aluminium where excellent direct adhesion is required.
• When the application demands resistance to extreme temperatures (–40°C to +180°C), chemicals, or industrial pollution.

Don't use this when

• Not for: Joints in exterior applications between ceramic tiles and light-coloured natural stone, as dirt accumulation can compromise aesthetics.
• Not for: Acid-sensitive substrates like limestone; use a neutral silicone sealant such as Mapesil LM instead to prevent etching or discolouration.
• Not for: Highly plasticised materials or bituminous surfaces, as leachable substances can compromise bonding or sealant integrity.
• Not for: Floor joints subject to heavy traffic; consider a polyurethane (e.g., Mapeflex PU 45 FT) or epoxy-polyurethane sealant (e.g., Mapeflex E-PU 21 SL) for these demanding applications.
• Not for: Sealing aquariums, due to specific requirements for continuous immersion and non-toxicity to aquatic life.

Choosing the right Mapei sealant

While Mapesil AC provides exceptional performance for many applications, specific situations call for alternative Mapei solutions. For acid-sensitive substrates like limestone, where an acetic-cure sealant could cause etching or discolouration, Mapesil LM offers a neutral-cure silicone alternative. Similarly, for floor joints exposed to heavy foot or vehicle traffic, a higher-strength, harder-wearing sealant like Mapeflex PU 45 FT (polyurethane) or Mapeflex E-PU 21 SL (epoxy-polyurethane) is engineered for that specific load and abrasion.