Low modulus sealants are stretchy but not the most hardwearing, they are the best option for sealing glass wall assemblies, perimeter seals, on curtain walling, perimeter sealing of polyester powder coated frames and glazing of windows in swimming pool buildings. These sealants offer better adhesion and accommodate more movement. These sealants are generally very long lasting.
High modulus sealants are less stretchy but more hardwearing, they are recommended for use in sealing Baths, showers, sinks, wash basins, kitchen worktops and many other sanitary and internal applications. They can also be used on Shop fronts, showcases and glass to glass joints.
Acetoxy silicone sealants release acetic acid (which smells a little like vinegar) as they cure, this is the most commonly used – it is more rigid and the full cure is quick. On the downside, it generally has poor adhesion and leaves much to be desired in how well it ‘sticks’ to PVC-U, most other plastics, and glass, aluminium and Polycarbonate.
Neutral (meaning neutral alcoxy) silicone sealants release alcohol as they cure, and has almost no smell, they have better adhesive properties for a greater number of materials including PVC-U, most other plastics, glass, aluminium, lead, stone and masonry and Polycarbonate. On the downside, they can be more expensive and is slower to cure at one to five days depending on thickness, temperature and humidity conditions.
Which sealant for which application?
Low Modulus Acetoxy (LMA) sealants are the cost-effective “all-rounders”, they are suitable for a wide variety of general building, sanitary (when they contain a fungicide), glazing interior and exterior applications and adhere to many common building materials.
Low Modulus Neutral (LMN) sealants are the best option for the sealing of UPVC Window or Door Frames (exterior). They offer better adhesion, accommodate more movement and are generally longer lasting than LMA’s.
High Modulus Acetoxy (HMA) sealants are most commonly used for kitchen and sanitary applications (ensure the sealant contains a fungicide).
General purpose and builders silicone: this is the basic general purpose silicone sealant. It sticks well to most building materials and offers good elasticity and durability but usually do not contain any fungicides.
Sanitary Silicone: a silicone that includes a fungicide to reduce the formation of mould on silicone that is frequently exposed to moisture. To reduce the chance of mould forming it is important to get the surface of the silicone joint as smooth as possible. This also makes cleaning it easier. Improving ventilation in rooms that suffer persistent high moisture levels can also help reduce mould growth.
Glazing Silicone: typically a sealant that cures to a very clear finish and offers very good adhesion to glass. Used for bedding in glazing panels, and sealing around the edge of the glass in windows and doors.
Frame Sealant Silicone: this is a tough sealant designed to accommodate large amounts of movement, and it is also better able to withstand exposure to the weather and UV radiation than other types of sealant. It adheres well to most building materials. It is designed for sealing around window and door frames. Often available in a variety of colours designed to match wood and other common framing materials.
Neutral Cure Silicone: most silicone sealants release acetic acid while curing. This gives off a characteristic vinegar-like smell. In some circumstances, this odour may be undesirable, or the acetic acid may have a negative impact on the materials being sealed (for example some clear polycarbonate materials may suffer slight staining when exposed to acetic acid). Neutral cure silicone products reduce or eliminate the production of acetic acid while curing. Often the better quality sealants also tend to be neutral cure products.
High-Temperature Silicone: designed to withstand high temperatures when cured (typically up to 260°C, but 300°C rated is available). These are often found in applications in electrical and industrial equipment, and for making seals between high-temperature surfaces.
Aquarium Silicone: a very tough silicone designed for glueing and sealing glass in aquarium applications. It is not advised to use building silicones for fish tank construction.
Other specialist silicones: there are a number of other specialist silicone products designed for different industrial uses. For example in the electronics industry. Many of these are designed for coating circuit boards to resist moisture penetration, or for “potting” assemblies, joints, and circuits.
Post time: Aug-22-2019