These stains are not in vinyl yet, but will be if.
You use acetone, undiluted citrus cleaners, MEK or ANYTHING that dissolved the vinyl itself. I have had lots of experience with this type of stain from doing boat shows etc and have lots of feedback from other people too. The stains from bread wrapper, some charts, newsprint etc are down in the "pores" of the viny and dissolbed in the plasticizer that is in between the long chain PVC molecules. Therefore you dissolve it out with something that will not dissolve the vinyl but WILL dissolve and replace the plasticers. To finish and to prevent such stains in the future, you need a physical barrier "plastic skin" type sealant not just a "dressing" that merely shines the surface. I think you will find all the info you need at the Gelcoat and Plastics Forum. Thanks Jim W
