3M Fire Barrier Moldable Putty Stix MP+ Red — Intumescent, Re-Enterable Firestop Putty (Up to 4 Hours)

Overview

3M Fire Barrier Moldable Putty Stix MP+ is a one-part, re-enterable intumescent putty that you can hand-form to seal penetrations and blank openings in fire-rated assemblies. Its dark red color helps with visibility during installation, making it easier to confirm a complete, continuous seal. The product is designed for industrial environments and supports flexible adaptation to irregular shapes and gaps.

Performance and Benefits

The putty delivers firestop performance that has been tested up to 4 hours in accordance with ASTM E814 (UL 1479) and CAN/ULC S115. In the right wall assembly, it can contribute to an STC rating of 56, supporting enhanced sound isolation where required. As a ready-to-use material, it can be formed to fit through penetrations and blank openings without special tools.

• One-part, ready-to-use, re-enterable putty that stays workable over time
• Forms a draft seal and a cold smoke barrier to help reduce air and smoke transfer
• Noncorrosive and compatible with synthetic cable jackets
• Dark red color aids visual verification during installation
• Labor-friendly, adaptable for irregular openings and through-penetrations

Practical Applications

Use MP+ to seal through penetrations and blank openings in fire-rated assemblies across industrial facilities. The material can be re-entered for adjustments or repairs as installations evolve, without crumbling or losing workability. It is tailored for settings where reliable firestop performance, air sealing, and noise containment are priorities.

• Seal around pipes, conduits, and cables in walls and floors
• Fill blank openings in fire-rated assemblies before final finishing
• Provide a long-lasting, maintenance-friendly seal that can be reworked if needed
• Support draft and cold smoke control in occupied spaces
• Ideal for industrial/occupational environments; not intended for consumer sale or use

Product Details and Guidelines

MP+ is designed to be noncorrosive and compatible with synthetic cable jackets, helping protect metal components and electrical insulation during installation. The material remains workable over time, offering a practical option for ongoing projects or future re-entry needs. For best results, follow standard firestop installation practices and consult the product’s listed specifications.