Home > Companies > Dow Silicones Belgium SPRL > DOWSIL™ 335 Butyl Sealant Black

A heat applied polyisobutylene for use as the primary seal in insulating glass in commercial and residential applications. It is suitable for high performance glazing systems, particularly where elevated temperatures are anticipated in warmer climates.

Features and benefits:

  • Meets the requirements according to EN 1279-4.
  • Compatible with all Dow facade silicones.
  • The sealant is suitable as the primary seal in air and gas-filled double and triple insulating glass units and meets the requirements according to EN 1279 in an IG system. As valid for any other technology, a proper application and fabrication of the insulating glass unit is required.
  • Good physical adhesion to glass and a variety of warm edge and standard spacers.
  • Solvent-free and odourless.
  • Compatible with the DOWSIL range of neutral facade silicone materials.
  • Can be applied with common IGU butylizers.


Suitable for gas-filled triple and double glazed insulating glass units (IGU) using warm-edge spacers and standard spacers manufactured from plastic, metal or combinations of both.

Standard product features



Technical characteristics:

  • Composition: Polyisobutylene, non-reactive and solvent-free Consistency: Solid compound, non-slump.
  • Application temperature: 125–145°C.
  • Specific gravity (to EN ISO 1183): 1.26 g/mL
  • Corrosiveness: Non-corrosive.
  • Gas permeability (to EN 1279-4: 2018): 0.0117 g/m²·24h (0.00049 g/m²·h).
  • Water vapour permeability 2.0 mm film (to EN 1279-4: 2018): 0.05 g/m²·24h.
  • Volatile content (to EN 1279-4: 2018): ≤0.001%.
  • Melting rate (MVR, meltflow modular to ISO 1133B) for Black: 9–12 cm³/10 minutes.

NBS Specification

NBS Create logo
This product is associated with the following NBS Create clause:
45-55-75/350 Glazing compounds or sealants

Product specification

An important note about specifying



Dow Silicones Belgium SPRL


+32 64 888 000

Product reference

DOWSIL™ 335 Butyl Sealant Black

Manufacturer details

Parc Industriel - Zone C,
Rue Jules Bordet,
Seneffe, B-7180,
Tel +32 64 888 000
Fax +32 64 888 950
NBS Plus
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