G4 Pond Sealant Ref: 142 Description Available to order only - 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.