Silicone Sealants are a man-made polymer, it has a backbone of silicon and oxygen. To make silicone, silicon is extracted from silica and passed through hydrocarbons to create a new polymer with an inorganic silicone-oxygen backbone and carbon-based side groups. What that means is that while the silicone might come from a relatively benign and plentiful resource like sand, the hydrocarbons in silicone come from fossil sources like petroleum and natural gas. So silicone is a kind of hybrid material.
Acrylic Sealants are the economical, paintable alternative to silicone sealants; they are suitable for sealing and filling joints around aluminium, wood and UPVC window and door frames. However the external application of this form of sealant is very much ruled by the weather, conditions must by dry and preferably warm when applying. They also do not offer the same flexibility as a silicone.
Intumescent Sealants are designed for fire retarding constructions and generally have acoustic properties. They are suitable for indoor joints where a fire retardant seal is required to prevent the passage of smoke and vapours. For exterior use, use a fire retardant silicone.
Polymer Sealants are another “all rounder”; they have great durability, flexibility, excellent adhesion to non-porous surfaces, will bond to damp surfaces and are paintable. They are best used as an adhesive or sealant on surfaces that experience frequent vibration or strain. They are also ideal for gluing panels, skirting boards, windows, mirrors and insulation materials.
Polysulphide Sealants are designed to seal joints subject to movement where a tough, flexible, watertight seal is required. This product is no longer available and sites tend to use Polyurethane for applications where Polysuphide was previously used.
Polyurethane Sealants have first rate resistance to water, permanent elasticity under all climate conditions and excellent adhesion to metal and fibreglass; they are most commonly used for car, caravan and mobile home applications. Low Modulus Polyurethane Sealants are also safe to use in aquariums and terrariums, as once they are fully cured harmful solvents have evaporated making them inert.
Roof and Gutter Sealants are rubberised sealants specially developed for repairing leaking gutters, downpipes and flashings. They can also be used for bedding roof sheets and felts.
Types of Silicone Sealant Cure - There are two main types of cure; Acetoxy and Neutral. Both curing types cure by reaction with atmospheric moisture.
Acetoxy cure sealants give off a vinegary odour whilst curing, are generally high modulus and faster curing than neutral cure sealants.
Neutral cure sealants are low modulus and almost odourless.
Types of Silicone Sealant Modulus - There are two types of modulus; Low Modulus and High Modulus.
Low Modulus sealants accommodate more movement - this is evident as they are softer to touch and are best used for exterior applications. Low Modulus sealants adhere to porous surfaces.
High Modulus sealants accommodate less movement and are best used for interior applications. High Modulus adhere best to non-porous surfaces.
Different Silicone Sealant Example Applications
High Modulus Acetoxy Cure Silicone Sealants are ideal for interior applications such as interior draught sealing around windows or doors, sealing kitchen units and electrical components. It also has many sanitary applications such sealing around baths, showers, glass and tiling but ensure the sealant contains a fungicide.
Low Modulus Neutral Cure Silicone Sealants are ideal for exterior applications such as the perimeter sealing of UPVC Window or Door Frames, panel joints and joints in concrete and other porous cement based materials as it has more of a weatherproof seal, excellent adhesion and accommodates more movement.
Low Modulus Acetoxy Cure Silicone 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 material. However it is important to note that they do not have the same life span or adhesion properties as the more specialised alternatives particularly on exterior applications.
Specialised Silicone Sealants Applications
Food Grade Silicone Sealants are designed for use in areas where food contact may occur including contact with raw meat. They are frequently used in refrigeration units and cold room environments due to their temperature and mildew resistance.
High Temperature Silicone Sealants are basically gasket sealants designed for forming gasket joints where an extremely high temperature resistance is necessary. They can also be used to seal and bond oven doors.
Aquarium Sealants are another form of silicone sealant, the only difference is they are non-toxic to fish and reptiles and therefore ideal for sealing aquariums and terrariums.
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