H.B Fuller FulasealPro 840NS Sealant

For cool room construction, refrigerated container components, and insulation panel installations, FulasealPro 840NS Sealant is a non-skinning, butyl-based sealant that creates a permanently plastic, moisture-resistant barrier. Formulated to remain wet and sticky inside concealed lap joints, it seals sandwich panels, Alucobond, and metal substrates without drying out, skinning, or cracking over time.

How it works

FulasealPro 840NS Sealant operates as a non-drying, permanently plastic sealant. Unlike standard elastomeric curing sealants, this butyl compound remains in a constant paste-like state, ensuring it does not skin or lose its tackiness inside closed assemblies. When clamped between sheet metal, Polystyrene, or Alucobond panels, the non-skinning formulation flows into small gaps to block air and moisture infiltration while resisting the growth of mould and mildew in damp or temperature-controlled environments. Because the chemistry is non-corrosive, it is safe for direct contact with sensitive metals like Zincalume, aluminium, and galvanised iron without the risk of chemical degradation or surface etching. It will not separate or bleed when applied to non-porous surfaces.

Numbers that matter

• -40°C to +50°C service temperature: Maintains its physical properties and sealing performance in extreme cold, preventing the joint barrier from freezing or failing in commercial refrigeration units and deep-freeze cool rooms.
• 15 lineal metres coverage: Yields approximately 15 metres of a 5mm bead per cartridge, allowing accurate material estimation for long panel runs and lap joints.
• +5°C to +35°C application temperature: Defines the safe environmental window for gunning the sealant onto cold or warm substrates during panel assembly.
• Indefinite shelf life: Stored between +5°C and +25°C in unopened packaging, the product remains usable without a strict expiration date, reducing stock waste.

Where to use it

FulasealPro 840NS Sealant is formulated for small joints and concealed applications on the following substrates:

• Steel, Stainless Steel, Galvanised iron, Zincalume, and Aluminium
• Sandwich Panels and Alucobond
• Polystyrene and Fiberglass
• Most plastics (requires pre-testing)

Limitations

• Non-elastomeric: Not suitable for joints where movement is expected, or in applications subject to dynamic stress.
• No exposed weathering: Not suitable where the sealant is exposed to direct weathering or dirt pick-up; use HB Fuller 770 Sanitary Silicone to seal these exposed areas.
• Vibration limits: Not suitable for applications involving constant vibration, such as caravans or truck bodies.
• Non-paintable: This product cannot be painted over.

Application clean-up and preparation

All surfaces must be clean, dry, sound, and free of dust, oil, old sealant, or other contaminants before application. Clean lightly contaminated surfaces using the two-rag wipe method with Isopropyl Alcohol (IPA) on a clean, lint-free cloth, ensuring the solvent does not dry directly on the substrate. For heavily contaminated surfaces, clean first with a generic wax and grease remover using the two-rag wipe method, followed by a final IPA clean.

Apply the sealant to one surface by holding the gun at a 45-degree angle and pushing the bead forward, then immediately combine the two surfaces. Uncured sealant can be cleaned up using an organic solvent such as mineral spirits.