Silicone sealant contains inorganic substance whereas polyurethane sealant is organic in its composition. Silicone sealants are easy to extrude and smooth off, resistant to ageing, high service temperatures and chemicals. They can adhere to building materials such as glass, ceramic and aluminium. They are often used for sealing expansion joints in wall and floor coverings of ceramic and cement that are not subject to heavy abrasion, plumbing fixtures and sanitary ware such as bathtubs, basins, showers, expansion joints in swimming pools, around doors, windows, utility cable, etc.
Polyurethane sealants on the other hand, can adhere to a wide range of building materials such as cement-based products, bricks, steel, aluminium, general pre-painted surfaces, glass, wood-based materials, gypsum, ceramics, plastics, etc. They have high mechanical and wear resistance, resistant to chemical and corrosion, are highly adhesive and paintable with elastic paint.
Polyurethane sealants are useful as a heavy-duty adhesive and sealant. It is suitable for industrial floors subject to vehicular traffic, concrete floors and walls, sealing pipe-work systems and cables, sealing general fillet joints, etc. It can also be used for constructing and finishing building works such as skirting boards, bathroom fittings, window sills, etc.
The drying process may vary. It may cure or set after 24 hours for internal application but when applying externally with a temperature of ±30⁰C, it may cure or set within a day. The rule of thumb is to touch the surface of the sealant to ensure that it is not tacky which indicates that the sealant is set.
Mapei have a polyurethane sealant that can adhere well to wood and wood-based materials. As for silicone sealants in the Mapei range, it is possible to use on wood, though it is required to apply an additional primer such as Primer FD to act as a bonding enhancer before applying silicone sealant. Primer FD can adhere well on concrete, wood, metal, painted surfaces, plastic and rubber.
Mould and algae will form when sealants are exposed to conditions of damp and high temperature. Certain elastic sealants may be able to delay mould and algae formation due to the presence of biocides that oppose the formation of efflorescence. Mapesil AC is formulated with biocides and BioBlock technology which extends mould/algae protection for a longer period of time, especially when correct, periodic maintenance is carried out on the sealant.