I referred to a Canadian Railways poster recently and the more eagle eyed of you may have noticed it being removed from Ebay as well
The reason : plastic coating
I had the same problem on an Austin Cooper a few months ago, in that case the plastic was stuck down rather firmly. It was in a very interesting hand painted style
Austin Cooper plastic coated
This particular poster came from a railway museum in Bristol so one has to wonder about their preservation techniques. Anyway, the plastic was gummed down rendering the Cooper virtually valueless.
Moving on 6 months and i am facing the same dilemma with my CNR poster. it is covered in a very thin layer of plastic. I am taking it in next week to see if its a heat laminate and can be removed. Here’s hoping ! I will let you know how I get on in a future post