Elastic sealants: a solution for every problem

Why should you use an elastic sealant?

Elastic sealants are specific products that help safeguard the integrity of breaks and gaps in structures even in the event of movements and deformations: joints, fissures, or cracks. In a structure exposed to atmospheric agents, water, dust, heat and noise are free to enter or escape through these breaks and gaps, thereby reducing living comfort and the durability of the structure.

An elastic seal, correctly executed, contributes to the durability and energy efficiency of the entire structure.

Are all elastic sealants made from silicone?

No. The elastic sealants category available on the market is now made up of various polymers: acrylic, bituminous, butyl, hybrid, polyurethane, and silicone polymers, each with its own specific physical-mechanical characteristics and specific areas of use.

Silicone sealants are just one of many different products in the elastic sealants category. The popularity of silicone sealants on the market, however, has led an (incorrect) use of the name of this group of products (silicone) and the name of the commodity category (elastic sealants): in fact, not all sealants are made of silicone.

Which are the best elastic sealants?

No elastic sealant is necessarily better than another one: each product group has specific physical-mechanical characteristics that make it particularly suitable for a particular type of application and less so for another type.

For illustrative purposes, here are the key strong points of the most common product groups in the elastic sealants category:

Acrylic sealants

      • easy to smooth

      • paintable with elastic paint

      • low-cost

Acetic silicone sealants

      • easy to extrude and smooth off

      • resistant to ageing

      • resistant to high service temperatures and chemicals

      • transparent version available (opalescent effect)

Neutral silicone sealants

      • easy to extrude and smooth off

      • adhere to a wide range of materials

      • resistant to ageing

      • resistant to high service temperatures and chemicals

      • transparent version available (translucent effect)

Polyurethane sealants

      • adhere to a wide range of materials

      • high mechanical and tear resistance

      • highly adhesive

      • paintable with elastic paint

Hybrid sealants

      • easy to extrude and smooth off

      • adhere to a wide range of materials, including damp surfaces

      • resistant to ageing

      • limited surface dust retention

      • transparent version available (crystal clear effect)


Epoxy-polyurethane sealants

      • easy to extrude and smooth off

      • strong and resistant to chemicals

      • paintable or pigmentable on site.

Which product can I use to seal and bond different materials?

MAPEFLEX MS45 is a one-component, multi-purpose, flexible sealant for sealing vertical and horizontal joints between different absorbent and non-absorbent materials, including damp substrates: also, once set, it is compatible with elastomeric paints from the Mapei range. The same product may also be used as an adhesive to bond building components and features thanks to its initial grab power, rapid-hardening properties and adhesive performances.

Which sealant can I use for natural stone floor and wall coverings?

MAPESIL LM is an anti-stain sealant ideal for all types of absorbent and acid-sensitive stone; its chemical composition impedes the migration of liquids between the sealant and substrate, thereby preventing unsightly stains forming along the edges of joints caused by using unsuitable sealant. The wide range of colours available, coordinated with Mapei coloured grouts, allows them to be matched with the different colours of the most commonly used types of stone on floors and façades.

Which sealant can I use for ceramic floor and wall coverings?

MAPESIL AC is a coloured sealant specific for forming elastic seals in ceramic floor and wall coverings, bathroom fixtures, shower cabins and windows frames. The quality of the MAPESIL AC pure acetic silicone formula with Mapei BioBlock technology guarantees the maximum level of durability and performance. The extensive colour range available (40 different shades matching the Mapei coloured grouts) enables any aesthetic requirement to be met.

Which anti-mould sealant can I use in bathrooms and kitchens?

If an elastic sealant is frequently exposed to damp environments, mould and algae will probably form on its surface. Since mould and algae are a natural chemical reaction between damp, high temperatures and organic material, no sealant is able to prevent their formation. Certain elastic sealants, however, are able to delay them from taking root in surfaces thanks to the presence of special biocides that oppose the formation of efflorescence. Many products from the MAPESIL range are formulated with biocides, but only MAPESIL AC and MAPESIL LM benefit from BioBlock technology which extends biological protection for a long time, especially when correct, periodic maintenance is carried out on the sealant.

Which sealant can I use for industrial floors?

If a sealant is used on horizontal surfaces subjected to severe mechanical and chemical stresses and loads, it must have the capacity to elastically absorb movements in the joints and be able to resist contact with chemical substances and exposure to mechanical stresses caused by passing heavy goods vehicles. In this case, it is important that the sealant chosen for this specific use guarantees a balanced compromise of elasticity, resistance to chemicals and mechanical properties: MAPEFLEX E-PU 21 SL two-component epoxy-polyurethane sealant or MAPEFLEX PU35 CR one-component polyurethane sealant could be the right solution. Because of the number of factors in play, which depends on the specific area of use of the flooring, a personalised Mapei consultation could identify the most appropriate product for each specific case.

Which anti-fire sealant can I use?

In many civil and industrial settings, limiting the risk of fire is a determining factor when choosing the sealant. Some sealing products are formulated to reduce this risk, thanks to their particularly effective resistance to fire and their reaction in the event of fire. If a fire does break out, MAPEFLEX AC-FR 2 acrylic sealant and MAPESIL FR silicone sealant specifically guarantee high resistance to fire (the ability to delay the passage of flames, smoke and heat through joints) and low reaction to fire (the property to emit only a controlled amount and density of smoke and to limit the formation of incandescent droplets).