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Intumescents & Mastics

SLS offer a full range of intumescent materials and mastics as part of our dedication to providing full solutions to every installation.

Particularly in the case of intumescents, this material is often used in conjunction with locks, hinges and fire doors to protect buildings from the spread of smoke and fire. An intumescent substance is a material that expands when it is heated. For the purpose of fire safety, intumescent material is commonly used a gasket around a fire door or window and in the event of a fire, the material will heat, expand and close the gap between door and door frame or window and window frame and in this way restrict the spread of smoke and harmful fumes around a building.

SLS offer the Astroflame range of intumescent products. Astroflame is a market leader in the development of intumescent materials and their products are widely recognised as the standard when there is a requirement to stop the spread of fire and smoke through a building. Please click on the logo below to visit the Astroflame website.

Intumescent materials are supplied in a variety of forms and can be applied to most applications where a gap would need to be sealed in the event of a fire. Some examples include the following -

Intumescent Fire Seals

A graphite based intumescent material contained within a PVC sleeve which is designed for fitting into rebates in either the door or door frame of fire resisting door assemblies. When activated by heat from the fire the intumescent material expands (intumesces) to many times its original volume to provide an effective fire resisting seal between the door and its frame against the passage of fire, smoke and hot gases.

Intumescent Fireseals are available with or without a cold smoke seal and all are supplied with a self adhesive backing tape as standard to facilitate quick and easy fitting. The seals are available in a choice of colours to suit your requirements or blend with decor.


Intumescent Fire Sheeting

A graphite based intumescent material available in various widths, which can be easily cut for fitting behind hinges, door closures and strike plates etc.





Intumescent Tape

A flexible self adhesive polymer based extruded intumescent material suitable for sealing wired or fire resistant glazing into wooden fire doors and fire resistant partitions. On exposure to heat from a fire the tape swells, thus prohibiting smoke and flame from passing through the aperture between wood and glass, providing resistance in excess of 1/2 hour. Supplied in roll form it offers the user a high performance, non load bearing tape for accurate placement, with no waste and requiring no specialist applications.



Intumescent Mastics

A one part fire rated intumescent acrylic mastic designed for sealing gaps around fire doors, window frames and for sealing joints, voids and irregular holes in fire rated structures, and for maintaining their integrity when sealing around pipes and cables that penetrate them.

The mastic has been independently tested in accordance with BS476: Part 20 & 22: 1987 and can provide up to 4 hours fire resistance depending on depth/width and volumetric area. Can be used on most construction substances, although we do recommend that a small area is tested on unusual substrates.

It can be used in most low movement joints up to 25mm wide with no slump and can be overpainted.


SLS Contracts, Concept House, Larchfield Road, Leeds, LS10 1QP

Phone - 0113 271 5665 Fax - 0113 271 5664 Email - enquiries@slsservices.co.uk