Adheseal Unobond FC Polyurethane Adhesive

Adheseal Unobond FC is a fast-setting, single-pack D4 liquid polyurethane adhesive supplied in a 6 kg bulk format for structural timber bonding, joinery, furniture and cabinet manufacture, exterior woodwork and wooden boat building. It is designed for higher-volume workshop and fabrication use where a moisture-curing polyurethane glue needs to be spread across larger bond areas rather than applied from a cartridge.

Unobond FC bonds porous materials to porous or compatible non-porous materials when moisture is available from at least one mating surface. During cure it foams and expands slightly into small surface irregularities, helping maximise contact across close-fitting joints.

Bulk polyurethane adhesive for joinery and fabrication

The 6 kg pail format makes Unobond FC particularly suited to production environments, architectural joinery, timber fabrication and larger bonding jobs. Typical applications include furniture and cabinet manufacture, wooden boat building, exterior woodwork, floor mouldings and skirting, display signs and general construction bonding.

• D4 water-resistant classification: Unobond FC's cured bond withstands a 72-hour boiling water test.
• Structural bond strength: tensile strength of 5 N/mm².
• Single-pack liquid polyurethane: ready to use with no mixing required.
• Working time: approximately 15 minutes at 23°C and 50% relative humidity, with a skin time of about 10 minutes.
• Full cure: approximately 24 hours at 23°C and 50% relative humidity, depending on temperature, humidity and substrate moisture.
• Service temperature: -30°C to +100°C after cure.
• Coverage: approximately 7.5 to 10 m² per litre, or about 42 to 60 m² per 6 kg drum depending on surface profile.

Compatible substrates

Unobond FC bonds compatible softwoods and hardwoods, veneer, melamine, particleboard, plasterboard, fibre cement sheeting, concrete, brick, masonry, aluminium, iron, steel, sheet metal, stainless steel, polystyrene and insulation foam. Many plastics can also be bonded after compatibility testing.

These materials can be bonded to themselves or to one another where moisture is available to activate the cure, giving Unobond FC a broad role in timber, mixed-material and fabrication assemblies.

Application and clamping

Bonding surfaces must be structurally sound, stable, clean and free from dust, oil, grease, release agents, curing compounds and other contamination. Concrete should be cured for at least 28 days. Lightly sand metal surfaces and clean them with a suitable solvent such as Adheseal Xylene before bonding.

Unobond FC is intended for close-fitting joints. Aim for a glue-line thickness of 0.1 mm to 0.25 mm and do not exceed 0.5 mm. Apply between 5°C and 35°C, spread the liquid adhesive evenly before the skin forms, assemble immediately and maintain even pressure while the adhesive cures. At 23°C and 50% relative humidity, clamps should remain in place for at least 60 minutes. Use approximately 50 PSI clamping pressure for softwoods and 150 PSI for hardwoods.

At least one surface must provide enough moisture for cure, with a minimum moisture content of 8%. In dry, cool conditions or on non-porous materials, a light mist of water on the opposing surface can assist curing. Allow squeeze-out to cure before removing it mechanically.

Important limitations

• Not a gap filler: Unobond FC is an adhesive rather than a mastic, and bond strength is reduced if the glue line exceeds the specified maximum thickness.
• Pressure is required during cure: keep the assembly clamped, screwed or nailed as appropriate.
• Do not use in totally confined or moisture-starved spaces: moisture or atmospheric humidity is required for cure.
• Do not use for mirror bonding or structural glazing.
• Test plastics and potentially incompatible materials before commercial use.

Unobond FC or cartridge Unobond?

Choose Unobond FC for higher-volume manufacturing, joinery and fabrication work where the 6 kg liquid format is practical for spreading over larger bond areas. For controlled gun application, smaller jobs and site work, Unobond provides the same D4 polyurethane adhesive category in a cartridge-applied gel format.

Compare the wider range of structural and specialist PU bonding products in our Polyurethane Adhesives collection.