Dowsil 688 Glazing Cladding Sealant

Technical Data Sheet
DOWSIL™ 688 Glazing and Cladding Sealant
One-part neutral cure silicone sealant
Features & • Adheres to a wide range of building materials and finishes

Benefits • Neutral cure; will not corrode galvanized/zinc-coated steel or attack concrete
• Excellent resistance to weathering, ultra-violet radiation, vibration, moisture, ozone,
temperature extremes, airborne pollutants, cleaning detergents and many solvents
• Long life reliability
• Meets International Standards such as CNS 8903, BS 5889, BS EN ISO11600 20LM
• Strong elastic seal capable of withstanding movements up to ± 25% of original joint
width
• Non-slumping; can be used in vertical and overhead joints
• Easy to use – one part, no mixing required
• Can be applied in any season
• Good weatherability – it is virtually unaffected by sunlight, rain, snow, ozone or
temperature extremes
• Easy to use
• Bonds to most common construction materials without use of primer
• Excellent recovery from extension and compression
• Ease of application – ready to use as supplied
Applications DOWSIL™ 688 Glazing and Cladding Sealant is a one-part neutral cure silicone sealant
designed for a wide range of glazing, weather sealing and professional caulking
applications. It will bond to form a strong weatherproof seal on most common building
materials.
Typical Properties
Specification Writers: These values are not intended for use in preparing specifications.
Test1 Property Unit Result

As Supplied – tested at 25°C, 50% relative humidity
Flow, Sag or Slump Nil
Approximate Working Time2 Minutes 10
1. ASTM: American Society for Testing and Materials

2. Sealant cure rate and working time may vary with temperature and humidity.
UNRESTRICTED – May be shared with anyone

®TMTrademark of The Dow Chemical Company (“Dow”) or an affiliated company of Dow
Page 1 of 4 © 2018–2019 The Dow Chemical Company. All rights reserved. Form No. 62-1420-01 E
Typical Properties (Cont.)
Test Property Unit Result

Tack Free Time:
Translucent Minutes 30
Colors Minutes 30
Specific Gravity:
Translucent 1.03
Colors 1.40
As Cured – After 7 days at 25°C, 50% relative humidity
Durometer Hardness, Shore A:
Translucent Points 27
Colors Points 32
ASTM D412 Ultimate Tensile Strength MPa 1.10
ASTM D412 Ultimate Elongation at Break % 400
Temperature Stability °C -20 to 120
Movement Capability ± 25
Description DOWSIL™ 688 Glazing and Cladding Sealant is one-part neutral cure, construction grade
sealant that easily extrudes in any weather. It quickly cures at room temperature by reaction
with moisture in the air to form a durable, flexible silicone rubber seal.
It has excellent unprimed-adhesion to most construction materials.
Specifications Meets the requirements of: CNS 8903 A 2136 SR-1-9030-A-N, BS 5889 Type B, BS EN
ISO11600 20LM.
SGBP 2019-2722
How to Use Please consult the application manual for detailed information on state-of-art application
methods and joint design. Please contact your local sales office for specific advice.
Preparation
Clean all joints and glazing pockets, removing all foreign matter and contaminants such as
grease, oil, dust, water, frost, surface dirt, old sealants, or glazing compounds and
protective coatings.

How to Use Application Method
(Cont.) 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. It is recommended that a field test be carried out prior to
application. To confirm optimum adhesion on either a porous or non-porous surface,
adhesion testing should always be carried out prior to the commencement of any project.
Please contact your local sales office for specific advice.
Apply DOWSIL™ 688 Glazing and Cladding Sealant in a continuous operation using a
positive pressure. Tool the sealant with light pressure to spread the sealant against the
backing material and joint surfaces before a skin forms. The applied sealant should be
tooled and masking tape removed before the sealant has formed a cured skin.
Handling PRODUCT SAFETY INFORMATION REQUIRED FOR SAFE USE IS NOT INCLUDED IN
Precautions THIS DOCUMENT. BEFORE HANDLING, READ PRODUCT AND SAFETY DATA SHEETS
AND CONTAINER LABELS FOR SAFE USE, PHYSICAL AND HEALTH HAZARD
INFORMATION. THE SAFETY DATA SHEET IS AVAILABLE ON THE DOW WEBSITE AT
DOW.COM, OR FROM YOUR DOW SALES APPLICATION ENGINEER, OR
DISTRIBUTOR, OR BY CALLING DOW CUSTOMER SERVICE.
Usable Life and Store in original unopened containers in a dry place. Storage temperature should not
Storage exceed 30°C. DOWSIL™ 688 Glazing and Cladding Sealant has a shelf life of 12 months
from date of manufacturing as noted with “use by” date printed on the packaging.
Packaging This product is supplied in 300 ml disposable plastic cartridges or 600 ml aluminum foil
Information sausage.
Limitations This product is neither tested nor represented as suitable for medical or pharmaceutical
uses.
DOWSIL™ 688 Glazing and Cladding Sealant is not recommended for use in continuous
water immersion, nor for below ground or other joints where excessive abrasion and
physical abuse are encountered.
It should not be applied:
• To build materials that bleed oils, plasticizers, or solvents – materials such as

impregnated wood, oil-based caulks and certain green or partially vulcanized rubber
gaskets and tapes.
• To copper or copper containing building materials.
• To surfaces in direct contact with food. This sealant has not been tested to determine
its status under Federal Food and Drug Administration regulations.
• To uncured sealant other than DOWSIL™ 688 Glazing and Cladding Sealant. Sealant
with different cure chemistry, such as one part structural sealants, should be fully cured
before DOWSIL™ 688 Glazing and Cladding Sealant is applied.

Health And To support customers in their product safety needs, Dow has an extensive Product
Environmental Stewardship organization and a team of product safety and regulatory compliance specialists
available in each area.
Information
For further information, please see our website, dow.com or consult your local Dow
representative.
dow.com 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 our 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’s sole warranty is that our products will meet the 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.
TO THE FULLEST EXTENT PERMITTED BY APPLICABLE LAW, DOW SPECIFICALLY DISCLAIMS ANY OTHER
EXPRESS OR IMPLIED WARRANTY OF FITNESS FOR A PARTICULAR PURPOSE OR MERCHANTABILITY.
DOW DISCLAIMS LIABILITY FOR ANY INCIDENTAL OR CONSEQUENTIAL DAMAGES.
Page 4 of 4 ® Trademark of The Dow Chemical Company Form No. 62-1420-01 E

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Technical Data Sheet

DOWSIL™ 688 Glazing and Cladding Sealant

One-part neutral cure silicone sealant

Features & • Adheres to a wide range of building materials and finishes

Test1 Property Unit Result

1. ASTM: American Society for Testing and Materials

UNRESTRICTED – May be shared with anyone

Test Property Unit Result

It has excellent unprimed-adhesion to most construction materials.

UNRESTRICTED – May be shared with anyone

It should not be applied:

• To build materials that bleed oils, plasticizers, or solvents – materials such as

UNRESTRICTED – May be shared with anyone

dow.com LIMITED WARRANTY INFORMATION – PLEASE READ CAREFULLY

DOW DISCLAIMS LIABILITY FOR ANY INCIDENTAL OR CONSEQUENTIAL DAMAGES.

Page 4 of 4 ® Trademark of The Dow Chemical Company Form No. 62-1420-01 E

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