N-Mastic is a non-skinning polybutene-based compound. It will remain permanently soft and paste-like.


N-Mastic is suitable for sealing concealed lap joints between plastics, metals, timber, glass, masonry, and expanded foam panels.

It may be used in the installation of cool rooms, prefabricated construction and gasket sealed windscreens to exclude draughts and water penetration through joints in materials.

Product Range

Product Code: 9300697100054

  • Size & Pack Type: 410g cartridge
  • Color: White

Technical Features

  • Non-hardening – remains permanently flexible to provide a lasting seal
  • Good adhesion – adheres well to most substrates
  • Moisture resistance – provides an excellent barrier to moisture vapour
  • Microbe resistance – resists microbial attack
  • Low shrinkage – avoids the risk of sealant pulling away from joint surfaces
  • Wide service temperatures – withstands –40oC to +80oC service conditions

Application Tips

Due to the non-skinning, non-hardening nature of the sealant, N-Mastic should not be used in exposed joints where dirt pick-up or hand contact can be a problem.

As N-Mastic is not elastomeric, it should not be used in areas subject to considerable dynamic stress.

Although N-Mastic is resistant to static pressures, a curing sealant is recommended where this is a critical factor.

N-Mastic is not recommended for sealing lap joints in mobile homes, truck bodies, etc., as significant vibration and flexing occur during travel.

Technical Details and Performance

Indicative information only, not to be used for setting specifications.



Specific Gravity




Slump (MIL-S-8802, @ 32oC )

2.5mm maximum

Viscosity (Brookfield HAF 7/2 @ 25oC )

10,000 – 14,000 Poise

Flash Point


Storage Life (25oC )

24 months


Plastic cartridge (410g)

Performance Properties

Shrinkage (% maximum)


Service Temperature

–40oC to +80oC

Life Expectancy

Up to 20 years

Clean Up

Sealant may be removed with a cloth dampened with kerosene or mineral spirits

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