SIKAFLEX®-521 UV – MULTI-PURPOSE ELASTIC SEALANT (300 ml)

Key Features

• High-performance, UV-resistant, one-component elastic sealant based on Sika Silane-terminated polymer (STP) technology

• Excellent adhesion to a wide range of substrates without primer

• Permanent elasticity and high weathering resistance

• Non-corrosive, solvent-free, and isocyanate-free formulation

• Resistant to aging, cracking, and sunlight exposure

• Can be painted and sanded once cured

• Ideal for indoor and outdoor industrial sealing applications

• Available in 300 ml cartridges (white, grey, or black)

Product Description

Sikaflex®-521 UV is a high-quality, elastic, moisture-curing sealant designed for long-term sealing and bonding in industrial, transportation, and construction applications.
It combines excellent UV stability with strong adhesion to metals, plastics, ceramics, and painted surfaces — even without primers.
The product forms a durable, weatherproof seal resistant to vibration, temperature variation, and moisture exposure.
Its non-corrosive formulation ensures compatibility with sensitive materials and surfaces such as aluminum, GRP, and steel.

Technical Specifications

Application Fields

• Vehicle body, bus, trailer, and caravan sealing

• Construction and industrial assembly joints

• Marine, rail, and renewable energy equipment

• Roof, floor, and wall joint sealing where UV resistance is required

• Ideal replacement for silicone or polyurethane sealants in exposed environments

Certifications & Quality Assurance

• Genuine Sika® industrial-grade sealant

• Manufactured under ISO 9001 / ISO 14001 quality management systems

• Conforms to EC Directive 2004/42/EC (VOC regulations)

• Meets industrial and transportation OEM specifications

Storage & Handling

• Store unopened at temperatures between +5 °C and +25 °C in dry conditions

• Protect from direct sunlight and freezing

• Use only on clean, dry, dust-free surfaces

• For best results, apply with manual or pneumatic caulking gun

• Remove uncured sealant with Sika Remover-208 or suitable solvent

Package & Shipping

• Supplied in 300 ml cartridge (white, grey, or black)

• Leak-proof, durable packaging for workshop or field use

• Classified as non-dangerous goods for air, land, and sea transport

Warm Tips

• Ensure surfaces are clean and grease-free before application

• Apply as continuous bead; tool within 15 minutes for best finish

• Paintability depends on paint type — test beforehand

• Not suitable for glazing or structural bonding applications

• Replace cap immediately after use to avoid curing in nozzle