Home > Companies > Dow Silicones Belgium SPRL > DOWSIL™ 791 Weatherproofing Silicone Sealant

DOWSIL™ 791 Weatherproofing Silicone Sealant is a specified, premium performance weather sealing product specifically designed for general glazing and weathersealing in curtain wall and building facades.


  • Ideal for expansion, connection perimeter and other movement joints.
  • Neutral cure – suitable for use on coated glass, galvanized steel, masonry and other porous/ non-porous substrates.
  • Extension/ Compression movement capability of up to ±50% of the original joint width.


  • Excellent weatherability, virtually unaffected by sunlight, rain, snow or ozone.
  • Excellent unprimed adhesion to a wide variety of construction materials and building components.
  • Ease of application – ready to use as supplied.
  • Excellent rheology, low string upon gunning.

Standard product features


- Uncured – as tested at 23°C (73°F) and 50% RH:

  • Flow (sag or slump): Zero.
  • Working time: 20 minutes.
  • Extrusion rate: 140 g/minute.
  • Tack-free time: 40 minutes.
  • Curing time: 7–14 days.
  • VOC Content: 31 g/L.

- As cured – after 21 days at 25°C (77°F) and 50% RH:

  • Durometer hardness, Shore A: 34 points.
  • Joint movement capability: ±50%.
  • Tensile adhesion strength (at 25/ 50% extension): 0.276/ 0.414 MPa.



Custom colours are also available – contact manufacturer for details.

NBS Specification

NBS Create logo
This product is associated with the following NBS Create clause:
45-55-75/365 Weatherseal sealants for structural sealant/ bonded glazing

NBS Specification

NBS Buliding logo
This product is associated with the following NBS clauses:

Product specification

An important note about specifying



Dow Silicones Belgium SPRL


+32 64 888 000

Product reference

DOWSIL™ 791 Weatherproofing Silicone Sealant



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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