SKU: 5602

G4 Damp Sealer (2.5KG)

Name: G4 Damp Sealer (2.5KG)
Brand: Pond
SKU: 5602
Price: 44.34 GBP
Availability: InStock

£36.95

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G4 Damp Seal for concrete roofs and fibreglass applications

G4 Damp Seal is the correct G4 product when polyester resin and fibreglass will be applied over a suitable concrete surface.

It seals porous concrete before GRP sheathing and helps prevent alkali within the concrete from reacting with the polyester resin. It is suitable for concrete flat roofs and concrete or rendered ponds that will subsequently receive a fibreglass lining.

Concrete roof primer For fibreglass-lined ponds Apply before GRP

The G4 Damp Seal technical data states:
“Sealing concrete prior to fibre glass sheathing where alkali in concrete can react with resins.”

Which G4 product do I need?

Applying fibreglass or GRP afterwards?

Use G4 Damp Seal. This includes suitable concrete roofs and concrete or rendered ponds that will receive a polyester resin and fibreglass laminate.

Sealing a masonry pond without fibreglass?

Use G4 Pond Sealer as the finished standalone pond-sealing coating.

Shop G4 Pond Sealer

Do not confuse this product with G4 Pond Sealer.
G4 Pond Sealer is a standalone pond coating and should not be used as the primer beneath a subsequent fibreglass laminate.

Where would I use G4 Damp Seal?

Sealing suitable concrete flat roofs before polyester GRP sheathing
Preparing concrete or rendered ponds before installing a fibreglass lining
Sealing porous concrete where alkali could react with polyester resin
Damp-proof sealing of suitable floors and porous surfaces
Preparing plug surfaces before mould production
Improving the bond of GRP to suitable metal surfaces

Product description

G4 Damp Seal is a moisture-curing, single-part polyurethane varnish for sealing damp and porous surfaces. It forms a hard-wearing, non-porous coating and is particularly useful where concrete is being prepared for polyester GRP sheathing.

It can also be used on plug surfaces before applying a release agent and taking a mould, as release agents and polyester resins do not attack the G4 coating.

G4 Damp Seal may also be used to improve the bond of GRP to suitable metal surfaces. It withstands temperatures up to 200°C and provides good chemical resistance.

Coverage and tin-size guide

The manufacturer's nominal coverage rate is approximately 500g per m². For most sealing purposes, three coats are recommended to build a continuous surface film.

Tin size	Approximate three-coat coverage
1kg	Approximately 2m²
2.5kg	Approximately 5m²
5kg	Approximately 10m²
25kg	Approximately 50m²

The figures above relate to the manufacturer's nominal coverage rate for the complete sealing application. Actual consumption will vary according to the porosity, texture and condition of the substrate. Rough or highly absorbent concrete may require more material.

The modern technical data does not provide a separate coverage rate specifically for a single GRP bonding coat over concrete.

Key technical information

Application	Brush or roller
Coats	Three coats recommended for most sealing purposes
Drying time	Approximately 60–90 minutes
Recoat time	Recoat when finger tacky and do not allow more than four hours between coats
Application temperature	Can be applied at temperatures down to 0°C
Clean-up	Clean equipment immediately after use with Rustins Cellulose Thinners. Acetone may also be used on uncured product. Turpentine and White Spirit are unsuitable.

Concrete roof preparation and application

Inspect the concrete. The substrate must be sound, bare and sufficiently porous to accept the coating.
Clean and dry the surface. Remove paint, existing coatings, sealers, oil, grease, dust and any other contamination that could prevent adhesion.
Repair defects first. Repair loose, cracked or worn areas before applying G4 Damp Seal. G4 should not be relied upon to fill cracks, holes or defective concrete.
Apply by brush or roller. Work the product evenly into the porous surface and avoid allowing it to puddle in depressions.
Follow the required coating system. For most sealing purposes, the modern technical data recommends three coats.
Recoat when finger tacky. Do not allow more than four hours between coats.
Before applying GRP, check the laminating instructions. Follow the installation requirements and bonding window specified by the selected polyester GRP roofing system.

Direct-to-concrete GRP or overboard the roof?

Option 1: Apply GRP to suitable concrete

Where the concrete is bare, dry, sound, porous and properly prepared, G4 Damp Seal can be used to seal the concrete before the selected polyester resin and fibreglass system is applied.

Option 2: Install a new warm-roof deck

An alternative is to construct an insulated warm-roof build-up over the existing concrete or asphalt roof. The existing surface must be completely dry, clean, sound and in good condition.

The build-up can include suitable insulation, supporting battens and an 18mm OSB3 tongue-and-groove deck. The polyester GRP laminate and topcoat are then installed over the new OSB3 deck.

Because the fibreglass is applied to the new timber deck rather than directly to the concrete, G4 Damp Seal is not normally required as the GRP primer in this type of build-up.

The roof build-up, insulation, fixings and deck must be suitable for the structure and installed in accordance with the selected roofing system and relevant design requirements.

Features

Suitable before fibreglass sheathing over concrete
Suitable for concrete roofs and fibreglass-lined ponds
Nominal coverage rate of 500g per m²
Apply by brush or roller
Hard-wearing and non-porous
Moisture-curing, single-part polyurethane coating
Can be applied at temperatures down to 0°C
Good chemical and temperature resistance

G4 Damp Sealer (2.5KG)

£36.95

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G4 Damp Sealer (2.5KG)