PRODUCT DATA SHEET
Sikaflex -291
Version 03.01 (04 – 2023), en_US
012001202914001000
PRODUCT DATA SHEET
Sikaflex -291
Multifunctional adhesive sealant for marine applications
TYPICAL PRODUCT DATA (FURTHER VALUES SEE SAFETY DATA SHEET)
Chemical base 1-component polyurethane
Color (CQP001-1) White, black
Cure mechanism Moisture-curing
Density (uncured) depending on color1.3 kg/l (10.8 lb/gal)
Non-sag properties Good
Application temperature ambient5 40 C (41 104 F)
Skin time (CQP019-1) 60 minutes A
Open time (CQP526-1) 45 minutes A
Curing speed (CQP049-1) (see diagram 1)
Shrinkage (CQP014-1) 5 %
Shore A hardness (CQP023-1 / ISO 48-4) 40
Tensile strength (CQP036-1 / ISO 527) 1.8 MPa (260 psi)
Elongation at break (CQP036-1 / ISO 527) 500 %
Tear propagation resistance (CQP045-1 / ISO 34) 6 N/mm (35 pli)
Service temperature (CQP513-1)
4 hours
1 hour
-50 90 C (-58 194 F)
160 C (320 F)
180 C (356 F)
Shelf life 12 months B
CQP = Corporate Quality Procedure A) 23 C (73 F) / 50 % r. h. B) storage below 25 C (77 F)
DESCRIPTION
Sikaflex -291 is a non-sag 1-component poly-
urethane sealant specifically developed for the
marine market, which cures on exposure to at-
mospheric moisture.
PRODUCT BENEFITS
Bonds well to a wide variety of substrates
Good aging and weathering resistance
Elastic
Low odor
Non-corrosive
Can be over painted
Can be sanded
Listed under NSF Proprietary Substances
and Nonfood Compounds (black and white)
AREAS OF APPLICATION
Sikaflex -291 is a multipurpose product for use
in marine constructions. It is suitable to make
elastic, vibration-resistant joint seals, and can
also be used for a variety of interior sealing ap-
plications. Sikaflex -291 bonds well to the ma-
terials commonly used in marine construction
like wood, metals, metal primers and paint
coatings (2-C systems), ceramic materials and
plastics (GRP, etc.). Sikaflex -291 must not be
used to seal plastics that are prone to stress
cracking (e.g. Plexiglas, Polycarbonate, etc.).
Once cured, Sikaflex -291 can easily be sanded
as required.
This product is suitable for experienced profes-
sional users only. Test with actual substrates
and conditions have to be performed to ensure
adhesion and material compatibility.
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CURE MECHANISM
Sikaflex -291 cures by reaction with atmo-
spheric moisture. At low temperatures, the wa-
ter content of the air is generally lower and the
curing reaction proceeds somewhat slower (see
diagram 1).
Diagram 1: Curing speed Sikaflex -291
CHEMICAL RESISTANCE
Sikaflex -291 is generally resistant to fresh wa-
ter, seawater, diluted acids and diluted caustic
solutions; temporarily resistant to fuels, miner-
al oils, vegetable and animal fats and oils; not
resistant to organic acids, glycolic alcohol, con-
centrated mineral acids and caustic solutions or
solvents.
METHOD OF APPLICATION
Surface Preparation
Surfaces must be clean, dry and free from
grease, oil and dust.
Surface treatment depends on the specific
nature of the substrates and is crucial for a long
lasting bond. Suggestions for surface prepara-
tion may be found on the current edition of the
appropriate Sika Pre-treatment Chart. Consider
that these suggestions are based on experience
and have in any case to be verified by tests on
original substrates.
Application
Sikaflex -291 can be processed between 5 C
and 40 C (41 F and 104 F), but changes in re-
activity and application properties have to be
considered. The optimum temperature for sub-
strate and sealant is between 15 C and 25 C
(59 F and 77 F).
Sikaflex -291 can be processed with manual,
pneumatic or electric driven piston guns.
Tooling and finishing
Tooling and finishing must be carried out within
the skin time of the product. It is recommen-
ded using Sika Slick. Other finishing agents
must be tested for suitability and compatibility
prior the use.
Removal
Uncured Sikaflex -291 can be removed from
tools and equipment with Sika Remover-208
or another suitable solvent. Once cured, the
material can only be removed mechanically.
Hands and exposed skin have to be washed im-
mediately using a suitable industrial hand
cleaner and water.
Do not use solvents on skin!
Overpainting
Sikaflex -291 can be best painted after forma-
tion of a skin. Painting could be improved by
treating the joint surface with Sika Aktivator-
100 or Sika Aktivator-205 prior to paint pro-
cess. If the paint requires a baking process (>
80 C), best performance is achieved by allow-
ing the sealant to fully cure first. All paints have
to be tested by carrying preliminary trials under
manufacturing conditions.
The elasticity of paints is usually lower than
that of sealants. This could lead to cracking of
the paint in the joint area.
FURTHER INFORMATION
The information herein is offered for general
guidance only. Advice on specific applications is
available on request from the Technical Depart-
ment of Sika Industry.
Copies of the following publications are avail-
able on request:
Safety Data Sheets
Sika Pre-treatment Chart
For 1-Component Polyurethanes
General Guidelines
Bonding and Sealing with 1-component
Sikaflex
PACKAGING INFORMATION
Cartridge 300 ml
Unipack 600 ml
Tube 3 oz
BASIS OF PRODUCT DATA
All technical data stated in this document are
based on laboratory tests. Actual measured
data may vary due to circumstances beyond
our control.
ENVIRONMENTAL, HEALTH AND
SAFETY
For further information and advice regarding
transportation, handling, storage and disposal
of chemical products, user should refer to the
actual Safety Data Sheets containing physical,
environmental, toxicological and other safety
related data. User must read the current actual
Safety Data Sheets before using any products.
In case of an emergency, call CHEMTREC at 1-
800-424-9300, International 703-527-3887.
LEGAL DISCLAIMER
Prior to each use of any product of Sika Corpor-
ation, its subsidiaries or affiliates ( SIKA ), the
user must always read and follow the warnings
and instructions on the product s most current
product label, Product Data Sheet and Safety
Data Sheet which are available at usa.sika.com
or by contacting SIKA s Technical Service De-
partment via email at tsmh@us.sika.com.
Nothing contained in any SIKA literature or ma-
terials relieves the user of the obligation to
read and follow the warnings and instructions
for each SIKA product as set forth in the current
product label, Product Data Sheet and Safety
Data Sheet prior to use of the SIKA product.
SIKA warrants this product for one year from
date of installation to be free from manufactur-
ing defects and to meet the technical proper-
ties on the current Product Data Sheet if used
as directed within the product s shelf life. User
determines suitability of product for intended
use and assumes all risks. User s and/or buyer s
sole remedy shall be limited to the purchase
price or replacement of this product exclusive
of any labor costs. NO OTHER WARRANTIES EX-
PRESS OR IMPLIED SHALL APPLY INCLUDING
ANY WARRANTY OF MERCHANTABILITY OR FIT-
NESS FOR A PARTICULAR PURPOSE. SIKA SHALL
NOT BE LIABLE UNDER ANY LEGAL THEORY FOR
SPECIAL OR CONSEQUENTIAL DAMAGES. SIKA
SHALL NOT BE RESPONSIBLE FOR THE USE OF
THIS PRODUCT IN A MANNER TO INFRINGE ON
ANY PATENT OR ANY OTHER INTELLECTUAL
PROPERTY RIGHTS HELD BY OTHERS. Sale of
SIKA products are subject to the Terms and
Conditions of Sale which are available at ht-
tps://usa.sika.com/en/group/SikaCorp/term-
sandconditions.html or by calling +1 800-933-
7452.
PRODUCT DATA SHEET
Sikaflex -291
Version 03.01 (04 – 2023), en_US
012001202914001000
Sika Corporation
30800 Stephenson Highway
Madison Heights, MI 48071
U.S.A.
Telephone: +1 248-577-0020
Email: tsmh@us.sika.com
www.sikausa.com
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