Firestop sealant ALFA FLEXI MASTIC

  • Maximum movement ability of the system up to 25%
  • Suitable for joint widths up to 30mm
  • The only technology available free of VOC
  • Dynamic flexibility in low and high modulus application
  • Rapid curing
  • Maximum strength achieved after 24 hours




The sealant ALFA FLEXI MASTIC is a high quality one-component sealant with good adhesion, suitable for use by professional fitters. It is technologically innovative material (non-reactive polymers), having a variety of applications in the construction industry inside of buildings, including painting, laying of floors, glazing, jointing, painting and tile laying. It has better performance than regular silicone and MSP as well as butyl- and acrylic-based products, such as sealing compounds and glue. It is the only sealant free of harmful emissions.

In the production of the sealant ALFA FLEXI MASTIC only non-reactive, environmentally friendly chemicals compatible with most building materials are used. They have a unique “dynamic flexibility” feature that compensates both natural and sudden movements of sealed or glued joints, which provides long-term functionality.

It may be difficult to find a suitable conventional sealant as they differ in terms of quality, chemical composition and the contained compounds. Each of them is suitable for one particular surface or method of application. ALFA FLEXI MASTIC solves this problem. You can use one product for almost all applications.


ALFA FLEXI MASTIC remains flexible and suitable for coating both with the alkyd- and water-based paints. It is suitable a.o. for:

• Sealing windows and doors in rooms

• Sealing particularly in areas where air quality is crucial

• Sealing in sanitary facilities, such as a bathroom, shower and toilet

• Filling gaps around furniture, kitchen appliances and sinks in the kitchen

• Filling gaps around the floor

• Fire retardant sealing of gaps and movable expansion joints

• Sealing decorative elements

• Preventing air access and performing sound insulation

ALFA FLEXI MASTIC can be used as a glue. It has a good grip just after application, becomes extremely hard after curing, which makes that materials stick together permanently. Easy to apply and ideal for joining typical structures.

ALFA FLEXI MASTIC is able to glue together most construction materials, including:

• Ceramics

• Plastics

• Wood

• Metal

• Gypsum

• Wall

• Stone


All surfaces must be clean, free of dirt and dust or other contaminants. The substrate may be moist, but not covered with water. Prior to application, use a damp brush to remove loose particles and ensure good contact for bonding. Primer coat is not usually needed.

In order to attain maximum binding strength, the depth of the joint should be equal to half of its width, but not less than 6 mm. It is recommended to use additional insulation, for example a backer rod made of foam or stone wool.

Cut the tip at a right angle and carefully fill the joint with mastic sealant. Apply the sealant flush to the joint edges for ten minutes until a film covers the surface. The sealant will shrink slightly during curing, so if you want the surface was even, apply a thicker layer.

For best results, finish the mastic with plastic trowel for joints or similar tool, preferably within 30 minutes.

Do not expose the joint to water, do not spray it with water or other liquid before a film appears (<30 min). The sealant, which is not cured, dissolves in water as it is environmentally friendly and water-based, contains no solvents.


Sealing of doors or windows in the room Alfa_Flexi_Mastic_1_RC2-PW-napis200
Filling of linear joints Alfa_Flexi_Mastic_2_RC2-PW-200
Sealing of wall and roof structures Alfa_Flexi_Mastic_3a_RC2_PW_1.0-200
Type Color Product code
300 ml white SOP025
300 ml grey SOP026
300 ml light-grey SOP027
300 ml anthracite SOP028
300 ml brown SOP029
300 ml black SOP030
600 ml white SOP031

W trakcie opracowywania.


European Technical Approval ETA 14/0189

Certificate of conformity 0843-CPR-0180

Preliminary tests carried out by Chiltern /B13057/01

Tested in accordance with EN 15651