Thanks for the advices . Think that the glue would be a gelatine glue so animal based like used in bookbinding . So first I will try on one of my old books to see if heat will release this glue . Wetting the paper would work then but the paper off the photo is old and the photographic layer maybe will be getting lose from the under layer . And that's not what would be very clever . So testing first and let you know what's come out .