Nitoseal MS250 - UV Resistant Elastomeric Joint Sealant

Product Overview

Nitoseal MS250 is a high-performance elastomeric joint sealant engineered for demanding applications requiring exceptional durability and aesthetic performance. Manufactured by Fosroc and based on Silyl Modified Polymers (SMP) technology, also known as Polyurethane hybrid or Duraflex® technology, Nitoseal MS250 combines the weathering and adhesion performance of silicone sealants with the toughness and durability of polyurethane sealants.

Key Features and Advantages

Performance Characteristics

• 50% Joint Movement Capability: Accommodates total 50% movement (±25%), allowing the sealant to flex and respond to structural movement without compromising integrity
• Outstanding UV Resistance: Maintains color and integrity in external applications with exceptional resistance to long-term weathering
• Excellent Adhesion: Provides primerless adhesion to concrete, timber, masonry, aluminium, metal, and ceramics without requiring primers
• Non-Staining: Will not stain masonry surfaces, making it ideal for visible applications
• Low Stringing: Smooth finish with minimal stringing for professional appearance

Environmental and Safety Advantages

• Very Low VOC Content: Contains only 12g/L of volatile organic compounds (ASTM D3960), indicating minimal environmental impact
• Solvent-Free Formulation: Contains no isocyanate, making it safer for applicators and the environment
• Blister-Free Cure: Performs reliably in high humidity or on saturated surface dry (SSD) surfaces without blistering
• Made in Australia: Manufactured locally to support supply chain reliability

Application Properties

• Easy to Extrude: Maintains workability even at low temperatures
• Paintable: Compatible with water-based paints, allowing for color customization after application
• Smooth, Non-Slump Paste: Maintains consistent form during application without sagging

Technical Specifications

Form and Properties

Joint Design Criteria

• Optimal Joint Width: 10mm to 35mm wide
• Extended Range: Capable of sealing joints from 5mm to 50mm under suitable conditions
• Width to Depth Ratio Requirements:
  • Minimum 10mm depth for joint widths between 10mm and 20mm
  • 2:1 ratio for joint widths greater than 20mm

Coverage Data

One 600ml sausage provides coverage of 6 metres of 10mm x 10mm sealant bead, enabling accurate project estimation and material planning.

Color Variants Available

Nitoseal MS250 is supplied in an extensive range of colors to match architectural specifications and aesthetic requirements:

• Nitoseal MS250 Black (FC920170-600ML)
• Nitoseal MS250 Off White (FC920172-600ML)
• Nitoseal MS250 White (FC920173-600ML)
• Nitoseal MS250 Dark Grey (FC920174-600ML)
• Nitoseal MS250 Beige (FC920175-600ML)
• Nitoseal MS250 Brick Red (FC920176-600ML)
• Nitoseal MS250 Redwood (FC920177-600ML)
• Nitoseal MS250 Dark Earth (FC920178-600ML)
• Nitoseal MS250 Sandstone (FC920179-600ML)
• Nitoseal MS250 Original Grey (FC920185-600ML)
• Nitoseal MS250 Pipeline Grey N43 (FC920171-600ML)
• Nitoseal MS250 Pale Brown (FC920169-600ML)
• Nitoseal MS250 Special Colour (FC930223-600ML) - Made to order with minimum order quantity of 360 and 14-21 day lead time

Recommended Uses

• Sealing moving or static joints in high-performance applications
• Precast or in-situ concrete structures
• Curtain walls and lightweight cladding
• Tilt-up slabs
• Brick and blockwork
• Most building materials

Bond Breaker Requirements

Critical for Optimal Performance: A bond breaker must be used in all joints with Nitoseal MS250 to prevent sealant contact with the back of the joint. This allows optimum sealant performance by enabling proper three-sided adhesion. Options include:

• Shallow Joints: Self-adhesive polyethylene tape for eliminating adhesion to the joint base
• Deep Joints: Backing strips such as Expandafoam Backing Rod to support the sealant while acting as a bond breaker

Paintability Specifications

Nitoseal MS250 is paintable with water-based paints and offers unique advantages for applications requiring painted finishes. Painting can be performed after a thick skin develops (typically 65+ minutes), with best results achieved no later than 7 days after application. The flexibility of coatings applied over Nitoseal MS250 must be considered to ensure they accommodate expected joint movement.

Important Limitation: Do not paint with solvent-based paints (enamels), as these are not compatible with the sealant formulation.

Storage and Shelf Life

• Shelf Life: 12 months when stored in original, unopened packaging
• Storage Conditions: Dry conditions between +10°C and 25°C with 55% relative humidity, away from direct sunlight and moisture

Supply Format

• Container Size: 600ml foil sausages
• Packaging: Supplied in cartons of 12
• Application Equipment: Compatible with standard 600ml sealant guns

Limitations and Restrictions

• Bituminous Surfaces: Do not apply to bituminous surfaces or allow bitumen to contact Nitoseal MS250
• Submersion: Not suitable for application under water or in continually immersed conditions
• Wet Surface Application: Do not apply to wet surfaces where free water is present

References

• [1] Fosroc_Nitoseal_MS250_TDS.pdf
• [2] Fosroc_Nitoseal_PU250_TDS.pdf
• [3] Fosroc_Nitoseal_PU400_TDS.pdf
• [4] Fosroc_Nitoseal_MS400_TDS.pdf