Flexible PVC contains a phthalate oil plasticizer that makes the material flexible. Some of that plasticizer can sit on the surface of a flexible PVC liner. Some solutions that use tank liners in may be sensitive to this oil. In which case Witt Lining Systems recommends leaching the liner.
Leaching the liner involves filling the tank with water and taking it slightly off neutral. We recommend an alkali solution as bases draw plasticizer out quicker than acids. It is also important that the leach bath be heated to 140 deg F. Let this solution sit at this temperature for 8-12 hours (12-24 hours for an acid solution) and it will pull off the surface plasticizers. Rinse the liner clean with water and the liner is now leached and ready for service.
These instructions also appear on our General Installation Instructions that are included with each liner as well as available on our website here.