Product Information
Silicone
Sealants
FEATURES
• Ideal for expansion, connection,
perimeter and other movement joints
• Neutral cure – suitable for use on
coated glass, galvanized steel,
copper, masonry and other porous
and non-porous substrates
• Low modulus sealant according to
ISO standards; medium modulus
according to Dow Corning standards
• Extension/compression movement
capability of up to ±50 percent of
the original joint width
BENEFITS
• Excellent weatherability, virtually
unaffected by sunlight, rain, snow,
ozone or temperature extremes
• Excellent unprimed adhesion to a
wide variety of construction
materials and building components,
including Kynar™1 and anodized
coated aluminum; for further
clarification, refer to the application
method in this data sheet
• Ease of application – ready to use
as supplied
• Excellent rheology, low string upon
gunning
• Meets global standards (America,
Asia and Europe)
• Compatible with all Dow Corning
structural sealants
COMPOSITION
• One-part, neutral-cure sealant
Dow Corning® 791
Silicone Weatherproofing Sealant
Neutral, one-part silicone sealant
APPLICATIONS
Dow Corning® 791 Silicone Weatherproofing Sealant is a specified, premium
performance weathersealing product specifically designed for general glazing
and weathersealing in curtainwall and building facades
TYPICAL PROPERTIES
Specification Writers: Please contact your local Dow Corning Sales Application Engineer
or Dow Corning Customer Service before writing specifications on this product.
Method Test Unit Result
Uncured – As Tested at 50% RH and 23°C (73°F)
ASTM1 D 2202 Flow (sag or slump) mm (inches) 0
ASTM C 603 Extrusion Rate g/minute 210
CTM2 98B Working Time minutes 15
ASTM C 679 Tack-free Time minutes 35
Curing Time days 7-14
CTM 97B Specific Gravity 1.52
Application Temperature Range °C (°F) -25 to 50 (-13 to 122)
VOC Content3 g/L 46
As Cured – After 7 days at 50% RH and 23°C (73°F)
ASTM D 2240 Durometer Hardness, Shore A points 30
ISO4 7389 Elastic Recovery percent 91
ISO 9047 Movement Capability percent ±50
ISO 11600 Sealant Class Low Modulus
25LM F and G
As Cured – After 28 days at 50% RH and 23°C (73°F) – 12 x 12 x 50 mm T.A. joint
(ISO 8339) [0.5 x 0.5 x 2 inch T.A. joint (ASTM C 1135)]
Tensile/Modulus at 25% Elongation MPa (psi) 0.3 (40)
Tensile at 50% Elongation MPa (psi) 0.35 (60)
Modulus at 100% Elongation MPa (psi) 0.4 (70)
Ultimate Tensile Strength MPa (psi) 0.75 (120)
Ultimate Elongation at Break percent 460
ASTM C 711 Service Temperature Range °C (°F) -50 to 150 (-58 to 302)
1ASTM – American Society for Testing and Materials.
2CTM – Corporate Test Method; copies of CTMs are available on request.
3Based on South Coast Air Quality Management District of California. Maximum VOC is listed both inclusive and
exclusive of water and exempt compounds. For a VOC data sheet for a specific sealant color, please send your request
toproduct.inquiry@dowcorning.com.
4ISO – International Standardisation Organisation.
DESCRIPTION
Dow Corning 791 Silicone Weatherproofing
Sealant is a one-part, neutralcure,
architectural grade sealant. It
easily extrudes in any weather and
quickly cures at room temperature by
reaction with moisture in the air to
form a durable, flexible silicone
rubber seal.
APPROVALS/
SPECIFICATIONS
Meets the requirements of:
• ASTM C- 920 Type S, Grade NS,
Class 50, Use NT, M, G, A
• ISO 11600 F&G-25LM
• GB/T 14683b G and F (China)
• BS 5889
• D 18540 Class NF
1Kynar is a trademark of Atofina Chemicals, Inc. • SNJF Vitrage et Façade Category 1
Colors
This product is available in 6 colors:
black, gray, bronze, limestone, precast
white and white.
HOW TO USE
Please consult the Dow Corning
Americas Technical Manual, Form No.
62-1112, for detailed information on
state-of-the-art application methods
and joint design. Please contact your
local Dow Corning Sales Application
Engineer for specific advice.
Preparation
Clean all joints removing all foreign
matter and contaminants such as
grease, oil, dust, water, frost, surface
dirt, old sealants or glazing compounds
and protective coatings.
Application Method
Install backing material or joint filler,
setting blocks, spacer shims and tapes.
Areas adjacent to joints may be
masked to ensure neat sealant lines.
Primer is generally not required on
non-porous surfaces. On porous
surfaces, Dow Corning recommends
that a test sample be carried out prior
to application. To confirm optimum
adhesion on either a porous or nonporous
surface, adhesion testing
should always be carried out prior to
the commencement of any project.
Please contact your local Dow Corning
Sales Application Engineer for
specific advice.
Apply Dow Corning 791 Silicone
Weatherproofing Sealant in a
continuous operation using a positive
pressure. Tool the sealant with light
pressure to spread the sealant against
backing material and the joint surfaces
before a skin forms. The applied
sealant should be tooled within 15
minutes or before a cured skin forms.
Remove masking tape as soon as the
bead is tooled.
HANDLING PRECAUTIONS
PRODUCT SAFETY INFORMATION
REQUIRED FOR SAFE USE IS NOT
INCLUDED IN THIS DOCUMENT.
BEFORE HANDLING, READ
PRODUCT AND MATERIAL SAFETY
DATA SHEETS AND CONTAINER
LABELS FOR SAFE USE, PHYSICAL
AND HEALTH HAZARD INFORMATION.
THE MATERIAL SAFETY
DATA SHEET IS AVAILABLE ON
THE DOW CORNING WEBSITE
ATWWW.DOWCORNING.COM,
OR FROM YOUR DOW CORNING
SALES APPLICATION ENGINEER,
OR DISTRIBUTOR, OR BY CALLING
DOW CORNING CUSTOMER SERVICE.
USABLE LIFE AND
STORAGE
When stored at or below 30°C (86°F)
in the original unopened containers,
Dow Corning 791 Silicone Weatherproofing
Sealant has a usable life of
12 months from the date of manufacture.
Refer to product packaging for
“Use By” date.
PACKAGING
Dow Corning 791 Silicone Weatherproofing
Sealant is available in 300-
and 310-mL (10.1- and 10.5-fl oz)
disposable cartridges and in 500- and
600-mL (16.9- and 20.3-fl oz) foil
sausages depending on location of
purchase. Please check with your local
Dow Corning Sales Application Engineer
for local packaging range availability.
LIMITATIONS
This product is not approved for use as
a structural sealant.
This product should not be applied:
• To building materials that bleed
oils, plasticizers or solvents, green
or partially vulcanized rubber
gaskets or tapes
• In totally confined spaces
• For continuous immersion in water
or in below-grade applications
• When surface temperatures exceed
50°C (122°F)
• To frost-laden or wet surfaces
This product is neither tested nor
represented as suitable for medical
or pharmaceutical uses.
HEALTH AND
ENVIRONMENTAL
INFORMATION
To support customers in their product
safety needs, Dow Corning has an
extensive Product Stewardship organization
and a team of Product Safety
and Regulatory Compliance (PS&RC)
specialists available in each area.
For further information, please see
our web site,www.dowcorning.com,
or consult your local Dow Corning
Sales Application Engineer.
LIMITED WARRANTY
INFORMATION – PLEASE
READ CAREFULLY
The information contained herein is
offered in good faith and is believed to
be accurate. However, because conditions
and methods of use of our
products are beyond our control, this
information should not be used in
substitution for customer’s tests to
ensure that Dow Corning’s products
are safe, effective, and fully satisfactory
for the intended end use. Suggestions
of use shall not be taken as inducements
to infringe any patent.
Dow Corning’s sole warranty is that
the product will meet the Dow Corning
sales specifications in effect at the
time of shipment.
Your exclusive remedy for breach of
such warranty is limited to refund of
purchase price or replacement of any
product shown to be other than as
warranted.
DOW CORNING SPECIFICALLY
DISCLAIMS ANY OTHER EXPRESS
OR IMPLIED WARRANTY OF FITNESS
FOR A PARTICULAR PURPOSE
OR MERCHANTABILITY.
DOW CORNING DISCLAIMS LIABILITY
FOR ANY INCIDENTAL
OR CONSEQUENTIAL DAMAGES.
A 20-year Weatherseal Limited Warranty
is available. Some testing may be required.
Consult your Dow Corning Sales
Application Engineer for details.
Printed in USA Dow Corning is a registered trademark of Dow Corning Corporation.
Form No. 62-1245F-01 AGP7200 ©2002, 2003, 2004 Dow Corning Corporation. All rights reserved.