(Reader’s question) I have a question for readers of the KSS website. Many, if not most, of the 1960’s souvenir sheets from South Korea have gum creases or folds that are especially prominent on the gum side of the sheets. With scans, you can see some of the folds on the face of the souvenir sheets.
See attachments for some examples of these gum sides. These creases can also be seen on the regular and commemoratives of that era, but seem to be more common on the souvenir sheets. Obviously these were caused somehow in the printing/gumming of these sheets. Does anyone have information on what caused these gum creases?