Sika Sikaflex® 221 Multi-Purpose Polyurethane Sealant/Adhesive - 10.3oz(300ml) Cartridge - Aluminum Gray

The Sika Sikaflex® 221 Multi-Purpose Polyurethane Sealant/Adhesive is a single-component, non-sag elastomer formulation designed for demanding sealing and bonding applications across construction, marine, and industrial environments. Supplied in a convenient 10.3 oz (300 ml) cartridge in aluminum gray, this product cures through atmospheric humidity exposure to form a durable, flexible seal capable of withstanding thermal cycling, moisture, and structural movement.

Sikaflex® 221 is formulated to ASTM C920 standards and carries UL 723 classification for surface-burning characteristics, making it suitable for applications requiring code compliance. The polyurethane chemistry delivers strong adhesion to concrete, metals, wood, glass, and most plastics without the need for primers in many substrates. The non-sag consistency allows vertical and overhead application without slumping, critical for edge sealing, joint work, and structural repairs where precision placement matters. Cure time depends on temperature and humidity; typically, initial tack develops within 24 hours with full cure achieved over 7 days.

This sealant/adhesive serves professionals and contractors engaged in structural assembly, waterproofing, panel bonding, and field repairs where single-component convenience and weather resistance are essential. The 300 ml cartridge format integrates with standard caulking guns for controlled application. Aluminum gray color blends with metal substrates, finished concrete, and composite materials common in industrial and construction settings. Users value Sikaflex® 221 for resilience in freeze-thaw cycles, UV exposure, and dynamic joint movement—performance characteristics that distinguish polyurethane sealants from acrylic or silicone alternatives in demanding field conditions.