The choice of substrates for siliconized release liners goes from glassine, to SCK, to CCK, PE/PP, and PET. Selecting the release liner is usually dependent on the application requirements.
For many years PET has been used for silicone release liners. It offers some advantages over typical paper based materials, like consistent gauge, strength and tear resistance, dimensional stability, and more.
In recent years, the supply of paper as a base sheet for silicone release liners has been volatile. Paper machines and paper mills' shutdown, conversions from silicone base sheet to other grades, and price fluctuation have become common. Consolidation through mergers and acquisitions has reduced the number of suppliers. Less suppliers calendared papers are being produced, with an increase in clay coated papers and “clay washed” base sheet. These factors, along with variation in pulp and paper processing, and surface treatments, has led to insecurity of some base sheets used as a viable silicone release liner.