G4 Pond Seal is a moisture cured polyurethane which forms a non porous seal on concrete, brick or porous stone. G4 uses the moisture in the air and substrate to cure or harden so it can be applied to slightly damp substrates. G4 can be applied in poor weather conditions, high humidity and at temperatures down to 0ºC. Ponds will normally be constructed with either brick, lightweight block or concrete block. With block work it is necessary to apply a cement render since the surface is to open and absorbent to seal with G4. It is not necessary to add waterproofing agents to the render mix when G4 is being applied since they increase the density of the render and can inhibit penetration of the G4. However, in practice, it is known that G4 performs well on renders containing waterproof agents. Fibre mesh can be used to increase the strength. It is necessary that the fibres are either burnt or sanded off prior to coating with G4 as some will project from the render and can act as a wick, since G4 will not bond to the fibres, which can result in leakage. It is also necessary to remove them since fibres will also damage the scales of fish. The cement render should be trowelled to an even surface but not to a smooth dense plaster like finish since this prevents the penetration of G4.
Bear in mind that a half-inch render should be kept damp for 3 days. New render should be allowed to harden for 21-28 days depending on conditions.
Consumption of G4:
- Standard Clear 3 coats = 550g/m² (for all 3 coats)
- Coloured = 1st and 2nd coats G4 standard = 410g/m² (for 2 coats) 3rd and 4th coats G4 coloured = 400g/m² (for 2 coats)