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

Sikaflex®-221 is the ultimate solution for marine and boating applications, offering superior adhesion and flexibility essential for maintaining the integrity of your vessel. Whether you're sealing joints, fastening components, or ensuring watertight connections, Sikaflex®-221 delivers reliable performance in harsh marine environments.

Product Overview

Sikaflex® 221 Multi-Purpose Polyurethane Sealant/Adhesive is a high-quality, non-sag 1-component polyurethane sealant and adhesive designed to provide durable, elastomeric seals that withstand the demanding conditions of marine settings. Available in a convenient 10.3oz (300ml) black cartridge, Sikaflex®-221 cures upon exposure to atmospheric humidity, forming a strong and long-lasting bond.

Key Features

Feature	Description
Elasticity	Highly elastic, allowing for movement and flexing without cracking.
Durability	Resistant to aging, weathering, and UV exposure, ensuring longevity in marine environments.
Non-Corrosive	Does not corrode or degrade metal substrates, making it ideal for boat construction and repairs.
Paintable	Can be sanded and overpainted to match your vessel’s aesthetics.
Regulatory Compliance	NSF registered and UL listed for potable water applications (available in black, gray, and white).

Applications in Marine and Boating

Sikaflex®-221 excels in a variety of marine applications, including:

• Sealing deck fittings and hardware to prevent water ingress
• Bonding hull components for enhanced structural integrity
• Attaching non-metal materials to metal surfaces
• Creating watertight seals around windows and hatches
• Repairing and maintaining boat interiors and exteriors

Compatibility

Sikaflex®-221 bonds exceptionally well with a wide range of substrates commonly found in marine environments:

• Wood
• Metals and metal primers
• Paint coatings (2-component systems)
• Ceramic materials
• Plastics

Technical Specifications

• Type: 1-component polyurethane sealant/adhesive
• Color: Black
• Size: 10.3oz (300ml) Cartridge
• Cure Time: Cures on exposure to atmospheric humidity
• Standards: Meets ASTM C920 Type S&A and ANSI/UL 723

Advantages for Marine Use

• Maintains flexibility in varying temperatures and conditions
• Provides a strong, permanent bond that resists marine stresses
• Easy to apply and clean, streamlining maintenance and repairs

Safety Information

WARNING: This product can expose you to chemicals which are known to the State of California to cause cancer, birth defects, or other reproductive harm. For more information, visit P65Warnings.ca.gov.

Additional Resources

Quick Guide (PDF)

Orders of physical products placed by 3 PM EST M-F typically ships the same day, if all requested items are in stock. Weekend orders will typically ship on Monday.

Shipping takes 2-7 days.

We currently ship to the Contiguous 48 States.

Life of Sailing merch is custom made for the customer after an order is placed. Total turnaround is typically 7-14 days from order to doorstep.