Bostik Seal-N-Flex 2641

DESCRIPTION

Bostik 2641 is a two component elastomeric polyurethane sealant with total joint movement of 50% formulated for sealing joints which require a high performance sealant. Bostik 2641 exhibits excellent resistance to sewage, sea water, oils, fuel, dilute acids and alkalis.

APPLICATIONS

Sewerage and waste water.

Water treament plants.

Digestion tanks.

Water reservoirs.

Seawalls.

Marine Installations.

Suitable for most building applications.

ADVANTAGES

+-25% joint movement.

Excellent resistance to sewage and sea water.

High abrasion resistance.

Suitable for most building applications.

STANDARDS

Bostik 2641 sealant exceeds the test requirements of federal specifications TT-S-277 (COM-NBS) for two component sealants as class A, non sag: and conforms to ASTM C920 standard specification for elastomeric joints sealants as type M. Grade NS, Class 25, use T A and M.

TABLE 1

BOSTIK 2641 TYPICAL UNCURED PROPERTIES

Property	Value	Test Method
Tool/Work time	30 mins	Bostik
Tack Free Time	45 mins	ASTM C679
Curing time at 25C	3-5 days	Dependant on humidity

TABLE 2

BOSTIK 2641 TYPICAL PROPERTIES

Property	Value	Test Method
Joint Movement	+/-25%	ASTM C719
Hardness (Shore A)	36	ASTM D2240
Tensile Strength	103N/CM2	ASTM D412
Adhesion in Peel	26N/CM2	100% Cohesive Failure ASTM C570
Ozone Resistance	Good	Bostik
U.V. Resistance	Good	ASTM C793

JOINT DESIGN

More joint movement can be accomodated in a thin bead of sealant than a thick bead. Bostik 2641 polyurethane sealant depth should be a minimum of 10mm and a maximum of 20mm. In joints greater than 20mm in width, the ratio of sealant depth should be 2:1. In joints greater than 20mm sealant depth should be 1:1. Back up materials to be used in water retaining structures must be rigid and non absorbent in order to prevent sealant distortion due to hydrostatic pressure. Materials impregnated with oil or bitume n materials are not to be used. Adhesion between the back up material and sealant must not occur because the excessive stresses exerted on the product may cause failure of the sealant.

PREPARATORY WORK:

Clean all joints by removing foreign matter and contaminants such as oil, dust, grease, frost, water surface dirt, old sealants and any protective coating. Porous substrates should be cleaned as necessary by grinding, saw cutting, blast cleaning (sand or water), mechanical abrading or a combination of these methods that will be required to provide a sound, clean and dry surface for sealant application. Dust, loose particles etc, should be blown out of joints with oil-free compressed air or vacuum cleaned. Non-porous and plastic surfaces should be cleaned by a solvent procedure or by mechanical means.

PRIMING

Bostik 2641 polyurethan weatherproofing sealant requires N-49 primer for masonary, aluminium, steel and most common building materials. Joints must be thoroughly dry before applying primer and sealant. If sealant is to be applied to a material with specially treated surfaces or of particularly unusual surface characteristics, consult Bostik for primer recommendations.
Prior to any use , however, it is always recommended that a bead of sealant be applied on the surface to test adhesion. See Pretested Adhesion to substrate Program. Bostik priming of all joints subjected to immersion. Allow Bostik N49 Primer a minimum of 30 minutes and a maximum of 6 hours prior to the application of 2641 sealant. Primed areas not sealed within 6 hours should be re-prepared and primed.

JOINT SIZE

Width	Depth	Mtr/Unit	Ltr/100mtr
10	10	60	10
15	10	39	15
20	10	30	20
30	15	13	4
40	20	7.5	80

MIXING

Bostik 2641 is a two-part sealant, provided as base and catalyst. All the catalyst must be thoroughly mixed for a minimum of five minutes with the base to avoid uncured areas streaking. Failure to follow mixing instructions implicitly can result if spotty cure, random cure or complete lack of cure of the sealant. Do not attempt to mix partial units, as the exact ratio of curing agent to base is essential for optimum performace.

METHOD OF APPLICATION

Install back-up material or joint fillers as specified. Apply Bostik 2641 polyurethane sealant in a continuous opoeration using a positive pressure adequate to properly fill and seal the joint. Tool the non-sag grade sealant with adequate pressure to spread the sealant against the back-up material and onto the joint surfaces. A tool with a concave profile is recommended to keep the sealant within the joint.

APPLICATION LIMITATIONS

Bostik 2641 sealant should not be applied with wet tooling techniques; using solvents, water or detergent/soap solutions is not recommended.

Bostik 2641 sealant should not be applied to surfaces with special protective or cosmetic coatings without prior consultation with the manufacturer. Such surfaces include, but are not limited to, mirrors, reflective glass, or surfaces coated with Teflon polyurethane or polypropylene.

Bostik 2641 sealant sealant should not be applied to unpredictable absorptive surfaces such as marble, limestone or granite unless a standard of appearance has been agreed on as a result of testing for stain and/or discolouration.

Bostik 2641 sealant cures by chemical means. The activator system used can be effectived by water before or during cure. The sealand should not be stored, applied or cured in areas where unusually high humidity of free water are present during the application or initial cure.

Bostik 2641 sealant should be allowed to cure for 14 days prior to subjecting to an intermittent or continuous head of water.
Bostik 2641 sealant should not be used in highly chlorinated areas such as swimming pools, spas etc without prior consultation with Bostik Technical Services.

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