G4 Pond Seal is a moisture cured polyurethane which forms a non-porous seal on concrete rendered ponds, G4 uses the moisture in the air and the render to harden, it can be applied to slightly damp surfaces, but it is important that the render is sufficiently dry to be porous so as to enable the first coat of G4 to bond and obtain a mechanical grip,G4 can be applied in poor weather conditions, high humidity and at temperatures down to zero degree's.
As a general rule the pond should be constructed to be structurally sound since the G4 only provides the waterproof seal, on no account use a P.V.A based sealer to seal or prime any surfaces, these materials can contain ammonia and also stop the G4 from adhering to the render.
Ponds will normally be constructed with either brick, lightweight block or concrete block and then rendered, it is not necessary to add waterproofing agents to the render mix as this will increase the density of the render and can inhibit penetration, if a waterproofing agent has been used, simply rub down the surface with an abrasive to obtain a key.
If a fibre is used to give strength to the render it is necessary to burn off or sand down any fibres that are on the surface, as any fibres that protrude will cause leakage, G4 will not bond to the fibres.
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, new render should be kept damp for the first three days and then allowed to harden for 21-28 days depending on conditions.
Method of application
Apply the first coat by brush, a roller can be used but it is necessary to avoid puddling of the G4 on the base, it is best to use a brush, allow the first coat to become finger tacky ( like cellotape ) or dry enough to walk upon carefully, approximately 45-60 minutes depending on humidity, then apply 2nd coat, when second coat is finger tacky apply third coat, no longer than 4 hours should pass between coats, if a colour is used, then use 2 coats of standard and 2 coats of colour, G4 is mechanically hard after 24 hours but must be given 72 hours to chemically cure, after which the pond can be washed down with plenty of water, drained, and can then be filled.
G4 Clear - 3 coats = 550g per sqm for the three coats
G4 Coloured - 2 coats of standard = 410g per sqm for 2 coats
and 2 coats of colour = 400g per sqm for 2 coats
G4 is available in Clear, Green and Black.