Koch Chemie S0.03 Hydro Foam Sealant. The Koch Chemie Hydro Foam Sealant S0.03 was developed to protect and improve various surfaces such as paint, glass and plastic. Creates a hydrophobic barrier that repels water and provides a silky finish. Thanks to its unique formula with high-gloss additives, it retains a depth of shine while avoiding discolouration and tarnishing of plastics. It is also suitable for waterproofing convertible roofs.