DOWSIL 791
Harmonization Code : 2901.10.00.00 | Acyclic hydrocarbons; Saturated
Main features
- +/-50% Weatherseal Movement
- Zero-Flow Weatherseal Application
- 20-Minute Weatherseal Tooling
Product Description
DOWSIL 791 Silicone Weatherproofing Sealant is a one-part, neutral-cure silicone sealant for weathersealing expansion, connection, perimeter and other movement joints in curtain walls and building facades. The ready-to-use material has zero measured flow, a 140 g/min extrusion rate and a 20-minute working time at 23 deg C and 50% relative humidity. After 21 days at 25 deg C and 50% relative humidity, the sealant reaches Shore A 34 hardness, 30 lb/in peel strength and +/- 50% joint movement capability. It is intended for general glazing and weatherseal joints and is not specified for structural glazing.
Key features
- Zero-flow weatherseal application: ASTM C639 flow is 0 at 23 deg C and 50% relative humidity.
- 20-minute working time: Supports placement and tooling before skin formation.
- +/- 50% joint movement: ASTM C719 movement capability applies after 21 days of cure.
Applications
Weathersealing expansion, connection, perimeter and movement joints in curtain walls and building facades.
TDS, SDS & Technical Documents
Technical Specifications
General Properties
Physical Properties
Mechanical Properties
Additional Information
As-supplied / before-processing properties
Typical uncured and cure-development properties tested at 23 deg C and 50% relative humidity unless noted.
| Property | Value | Unit | Method / condition |
|---|---|---|---|
| Flow, sag or slump | 0 | in | ASTM C639 |
| Extrusion rate | 140 | g/min | ASTM C603 |
| Working time | 20 | min | At 23 deg C and 50% RH |
| Tack-free time | 40 | min | ASTM C679; 25 deg C and 50% RH |
| Curing time | 7-14 | days | At 25 deg C and 50% RH |
| VOC content | 31 | g/L | SCAQMD basis |
After-processing / final-state properties
Typical properties after 21 days at 25 deg C and 50% relative humidity.
| Property | Value | Unit | Method / condition |
|---|---|---|---|
| Durometer hardness | 34 | Shore A | ASTM D2240 |
| Peel strength | 30 (5.4) | lb/in (kg/cm) | ASTM C794 |
| Joint movement capability | +/- 50 | % | ASTM C719 |
| Tensile adhesion at 25% extension | 40 (0.276) | psi (MPa) | ASTM C1135 |
| Tensile adhesion at 50% extension | 60 (0.) | psi (MPa) | ASTM C1135 |
