Mapesil AC Silicone Sealant

For sealing expansion joints in ceramic tile and cement wall and floor coverings, Mapesil AC Silicone Sealant provides a highly elastic acetic-crosslinking silicone barrier. It accommodates up to 25% movement in expansion joints, making it suitable for wet areas, kitchens, bathrooms, showers, and swimming pools where joint movement and moisture exposure are constant.

How it works

Mapesil AC is a solvent-free, thixotropic paste that can be applied to both horizontal and vertical joints without slumping. Upon exposure to atmospheric humidity, it crosslinks into an elastic gasket that inhibits mould growth and remains flexible down to -40°C and stable up to +180°C. The acetic cure mechanism ensures excellent direct adhesion to non-porous substrates including glass, ceramic, and anodised aluminium. For porous or challenging substrates like concrete, wood, metal, painted surfaces, and plastics, the sealant can be applied after pre-treating the joint walls with Primer FD bonding enhancer.

Numbers that matter

• ±25% movement capability: Classified as Class 25 LM under EN 15651-1, EN 15651-2, and EN 15651-3, allowing the cured joint to absorb thermal expansion and structural shifting without cohesive or adhesive failure.
• 800% elongation at break: Tested to ISO 37, verifying high elastic capacity to stretch well beyond standard joint limits before tearing.
• 10-minute skin time: Quick-forming surface skin (at +23°C and 50% R.H.) requires rapid finishing with a tool moistened with soapy water.
• Vulcanisation speed: Cures to a depth of 4 mm in 1 day and 10 mm in 7 days, dictating the time required before joints can be subjected to service loads.
• -40°C to +180°C service window: Retains its physical properties under extreme thermal stress, suitable for heating pipes, boilers, and exposed external facades.

Where to use it

Mapesil AC is suitable for residential, commercial, and industrial sealing applications:

• Sealing expansion joints in swimming pools and wet areas.
• Sealing joints between sinks, sanitary ware, and ceramic tiles in kitchens, bathrooms, and laundries.
• Forming elastic gaskets between construction elements in building, mechanical engineering, shipbuilding, and automotive assembly.
• Assembling glass tiles, glazing, window frames, and artistic stained glass windows.
• Sealing air ducts, water pipes, boilers, tanks, and service pipes.

Limitations

• Do not use in exterior joints between ceramic tiles and light-coloured natural stone, as dirt may accumulate near the joints.
• Do not use on acid-sensitive substrates such as limestone; use a neutral-curing silicone like Mapesil LM instead.
• Not recommended for highly plasticised materials or bituminous surfaces, as migrating substances can reduce bonding, alter the colour, and degrade the sealant.
• Do not use to seal aquariums.
• Do not use for floor joints subject to heavy traffic; use a polyurethane sealant like Mapeflex PU 45 FT or an epoxy-polyurethane sealant like Mapeflex E-PU 21 SL.
• Has limited resistance to solvents; avoid contact between unpolymerised sealant and any solvent to prevent cure inhibition.

Joint sizing and installation

To ensure free elongation and compression, the sealant must only adhere to the sides of the joint wall, not to the base. Use Mapefoam closed-cell polyethylene backing cord to control depth and prevent three-sided adhesion. Joint dimensions must be calculated as follows:

• For joints 10 mm wide: depth must equal the width (1:1 ratio).
• For joints between 11 mm and 20 mm wide: depth must be kept constant at 10 mm.
• For joints wider than 20 mm: depth must equal half the width (2:1 width-to-depth ratio).

When Primer FD is required, apply with a small brush and allow to dry for several minutes until the solvent evaporates before extruding Mapesil AC. Uncured sealant must be cleaned using ethyl acetate, petrol, or toluene; fully cured sealant can only be removed mechanically.