The liner that you use in your closure can do so many functions. At one end of the spectrum, it can give you tamper evidence by bonding to the container. This is generally done with some form of induction foil that can bond by an electro-magnetic field to the container face. The foil layer can also provide a barrier for product stability and can often leave residue on the container when removed. At the other end of the spectrum is a simple expanded PE foam that is a form of a gasket that when compressed will seal any imperfections particularly on the bottle face. In between these 2 lining options are a myriad of liners that will depend on the viscosity and chemical strength of your product. The attachment below aims to help you select the best option for your product.
Cormack Packaging
Performance Closure Systems
