I believe the White Lightning liners are stainless steel. I've never removed one.
Question; for those that HAVE removed a liner after it's been in there for a long time, did you have any particular difficulty in doing so? Oxidized iron and steel will take up more physical space than unoxidized metal, which can sometimes make loosening difficult. (Point of reference; we've all had to deal with nuts and bolts that have rusted together. Sometimes the bolts just shear off when trying to unstick things.)