GreyStuff Intumescent Water & Gas Tight Duct Sealant

FyBrid Technology
Developed with our proprietary FyBrid formulation, GreyStuff delivers enhanced durability, flexibility, and sealing performance, making it ideal for cables, ducts, and pipe penetrations.

Non-Hazardous & Installer Safe
100% MEKO-free, solvent-free, and halogen-free, GreyStuff is non hazardous, safe for use in confined spaces, explosive atmospheres (Ex zones), and environmentally sensitive sites.

Single-Component Application
Supplied as a ready-to-use compound, GreyStuff requires no mixing. This reduces installation time, eliminates waste, and ensures consistent results.

Tested Fire Performance
Independently tested to BS EN 1366-4 (Linear Joints) & Tested to UL94: 2013 ANSI / UL 94: 2018 standards, ensuring high levels of flame retardancy.

Water, Gas & Smoke Barrier
Provides a secure, long-lasting seal that prevents the ingress of groundwater, harmful gases, flammable vapours, and smoke, protecting cables and infrastructure.

Minimal Cable De-Rating
With a 20mm application thickness, GreyStuff achieves a thermal resistance of just 5.1 K/W. This allows efficient heat transfer, ensuring cables retain their full current-carrying capacity, even under high loads.

Microbial Defence
Enhanced resistance to fungi and bacteria, ensuring reliability in damp and contaminated duct environments.

Proudly British Made
Designed and manufactured in the UK, GreyStuff is backed by rigorous quality control and a trusted local supply chain.

Cure Time
GreyStuff cures at approximately 3–4mm per day, depending on ambient temperature and humidity. Higher humidity and warmer conditions accelerate curing.

Cleaning
Any uncured GreyStuff can be removed with a solvent-based wipe. Once cured, mechanical removal will be required.

Health & Safety
GreyStuff uses a neutral-curing, MEKO-free formulation, making it non-hazardous, halogen-free, and safe to use in confined spaces and explosive atmospheres (Ex zones).

Cable Suitability
Formulated as a single-component, solvent-free sealant, GreyStuff does not damage cable sheaths and will not stain duct or building surfaces

Storage & Shelf Life
Store GreyStuff in a cool, dry location away from direct sunlight.

Shelf Life: 12 months unopened
After opening: reseal securely and use within 1 month.

NOTE: Fire Test was performed on RedStuff, Not GreyStuff.  Please read further before purchasing

Tested by UL Germany to BS EN 1366-4:2021 (Linear Joints)

Solid Wall (150 mm thickness)
Joint length: 1 m
Joint width: 25 mm
Sealant depth: 20 mm (RedStuff)
Backing: 25mm Rockwool Type Y RWA45 (45kg/m³ mineral wool)
Fire resistance: 240mins integrity & insulation

Flexible Wall (asymmetrical construction)
One face: 2 × 12.5 mm plasterboard
Opposite face: solid wall
Joint length: 3m
Joint width: 25mm
Sealant depth: 20mm (RedStuff)
Backing: 25mm Rockwool Type Y RWA45 (45 kg/m³ mineral wool)
Fire resistance: 90 mins integrity & insulation

Note: Fire Certification – Important Note

Fire resistance is only applicable to an “as fire tested” system or otherwise approved configuration. The system achieves the certified rating only when the exact tested proprietary product is installed in the same way as approved during testing.

Always ensure your installation matches our fire test certification.

End users are responsible for verifying that GreyStuff is the correct system for their project.

For copies of fire test reports, please contact our technical department.

What is GreyStuff?
GreyStuff is a single-component, MEKO-free, neutral-curing duct sealant developed with our proprietary FyBrid technology. It provides durable, flexible sealing performance for cable ducts, pipe penetrations, and linear gaps, and is used across all DuctSeal systems.

Is GreyStuff Fire Tested?
GreyStuff has been tested as part of the DuctSeal FR system to BS EN 1366-3:2021 (Penetration Seals), achieving up to 4 hours of fire resistance.

GreyStuff has not been independently tested to BS EN 1366-4:2021 (Linear Gap Seals). Use of GreyStuff in fire-rated linear gap applications should therefore be carried out with customer/end-user authorisation.

RedStuff, which is chemically identical apart from the pigment component (<1%), has been independently tested to BS EN 1366-4:2021.

This pigment difference does not affect fire resistance, physical properties, or handling performance.

What’s the difference between GreyStuff and RedStuff?
The only difference is pigment. RedStuff and GreyStuff share the same formulation, with the exception of a <1% colour variation.

Is GreyStuff safe to use?
Yes. GreyStuff is a non-hazardous, zero-halogen, MEKO-free formulation. It is safe for use in confined spaces and explosive atmospheres (Ex zones), and it does not release harmful emissions during application or curing.

Can GreyStuff be re-entered or removed?
Yes. Once cured, GreyStuff reaches a rubber-like hardness that allows re-entry and resealing. Removal is easier with sharp tools, and should only be carried out when cables are de-energised.

AC Cable Solutions accepts no responsibility for damage caused during re-entry works.

Does GreyStuff damage cables?
No. GreyStuff is solvent-free and has been tested for compatibility with cable sheaths. It does not damage insulation or stain duct surfaces

How long does GreyStuff take to cure?
Cure rate is typically 3–4mm per day, depending on humidity and temperature

Can GreyStuff reduce cable performance?
No. At a 20mm thickness, GreyStuff has a thermal resistance of only 5.1 K/W, ensuring minimal cable de-rating and allowing cables to operate at full current capacity.

Where can GreyStuff be used?
GreyStuff is suitable for:

• Cable duct sealing (Only Fire Resistant when used with DuctSeal FR)
• Pipe penetrations (Only Fire Resistant when used with DuctSeal FR)
• Linear gap sealing (tested to BS EN 1366-4:2021) – Please read fire test section!
• Retrofit applications where re-entry is required
• Critical environments such as water utilities, data centres, petrol forecourts, telecoms, energy networks, and industrial facilities

Where is GreyStuff manufactured
GreyStuff is proudly manufactured in the UK, ensuring consistent quality, reliable supply, and compliance with British and European standards.