Sikaflex® NP 2

• ASTM C 920, Type M, Grade NS, Class 50, use NT, T, A, M, O* and I
• Federal Specification TT-S-00227E, Type II, Class A
• Canadian Standards Board CAN/CGSB-19.24-M90, Classification MCG-2-40-A-N, No. 81029
• CFI accepted
• Underwriters Laboratories Inc.® classified (fire resistance only)

*Refer to substrates in Uses.

Sikaflex® NP 2 is a multi-component polyurethane product.

15 months in original, unopened containers.

Sikaflex®-900 Color Packs: 5.5 years

Store in unopened containers in a cool, clean, dry area. Do not open containers until ready for use.

Linear Feet Per Gallon

Meters Per Liter

Table 1

Joint Width and Sealant Depth

Substrates must be structurally sound, fully cured, dry, and clean. Substrates should always be free of the following: dirt, loose particles, oil, grease, asphalt, tar, paint, wax, rust, waterproofing or curing and parting compounds, membrane materials, and sealant residue.

Concrete, Stone, and other Masonry

Clean by grinding, sandblasting, or wire brushing to expose a sound surface free of contamination and laitance.

Wood

New and weathered wood must be clean, dry, and sound. Scrape away loose paint to bare wood. Any coatings on wood must be tested to verify the adhesion of the sealant or to determine an appropriate primer.

Metal

Remove scale, rust, and loose coatings from metal to expose a bright white surface. Any coatings on metal must be tested to verify the adhesion of the sealant or to determine an appropriate primer.

1. Sikaflex® NP 2 is a multi-component system with a configuration of Part A, Part B, and a color pack. Pre-pigmented units do not use a color pack.
2. Transfer the entire contents of Sikaflex®-900 pigment color pack into the Part A. Use a spatula or knife to remove all the pigment from the container. Continue mixing with a slow-speed drill and slotted paddle until the color is uniform. During the process, scrape the sides and bottom of the mixing container several times to obtain a complete mix.
3. Transfer the entire content of Part B to pre-mixed Part A container using a spatula or margin trowel.
4. Part B must be mixed thoroughly with pre-mixed Part A. Scrape the sides of the container to ensure complete mixing of mixed Parts A and B. With a slow-speed drill and a sealant mixing paddle, mix for 4–6 minutes. Keep the paddle blade below the surface of the sealant to avoid whipping air into the sealant.

NOTE: 

• 1.5 gal unit kit use one Sikaflex®-900 pigment color pack
• 3.0 gal unit kit use two Sikaflex®-900 pigment color packs

Joint Preparation

1. The product may be used in sealant joints designed in accordance with SWR Institute's Sealants -The Professional's Guide.
2. In optimal conditions, the depth of the sealant should be 1/2 the width of the joint. The sealant joint depth (measured at the center) should always fall between the maximum depth of 1/2" and the minimum depth of 1/4". The maximum recommended joint width is 2". Refer to Table 1.
3. In deep joints, the sealant depth must be controlled by a closed-cell backer rod or soft backer rod. Where the joint depth does not permit the use of a backer rod, a bond breaker (polyethylene strip) must be used to prevent three-point bonding.
4. To maintain the recommended sealant depth, install the backer rod by compressing and rolling it into the joint channel without stretching it lengthwise. Closed cell backer rod should be about 1 ⁄8" (3 mm) larger in diameter than the width of the joint to allow for compression. The soft backer rod should be approximately 25% larger in diameter than the joint width. The sealant does not adhere to it, and no separate bond breaker is required. Do not prime or puncture the backer rod.

Priming

1. Sikaflex® NP 2 is considered a non-priming sealant, but special circumstances or substrates may require a primer. It is the user’s responsibility to check the adhesion of the cured sealant on typical test joints at the project site before and during application. Refer to the product data sheet on Sika® Primer-429 and consult Technical Service for additional information.
2. For immersion applications, Sika® Primer-429 must be used.
3. Apply primer full strength with a brush or clean cloth. A light, uniform coating is sufficient for most surfaces. Porous surfaces require more primer; however, do not over-apply.
4. Allow the primer to dry before applying Sikaflex® NP 2. Depending on temperature and humidity, the primer will be tack-free in 15–20 minutes. Priming and sealing must be done on the same day.

Application

1. Except when unusual job conditions dictate the use of a knife or spatula, apply Sikaflex® NP 2 by a professional bulk gun loaded at the job site. Fill joints from the bottom up to the exterior face by holding a properly sized nozzle against the joint bottom.
2. Dry tooling is recommended. Proper tooling results in the correct bead shape, neat joints, and optimal adhesion.
3. Best practices dictate that all caulking and sealing be done when temperatures are above 40 °F (4 °C) to avoid application to moisture-laden surfaces. Moisture on substrates will adversely affect adhesion.
4. Application may proceed as low as 40 °F (4 °C) if there is a certainty that substrates are completely dry, free of moisture, and clean as described under Surface Preparation.

Curing

The cure of Sikaflex® NP 2 varies with temperature and humidity. The following times assume 75 °F (24 °C), 50% relative humidity, and a joint 1/2" (13 mm) in width by 1/4" (6 mm) in depth. – Full cure: approximately 3 days.

Immediately after use and before the sealant has cured, clean equipment with SikaSwell®-990 or xylene. Cured sealant may be removed by cutting with a sharp-edged tool. Remove thin films by abrading.