The more well--known types of structure come from the dandy-roll [watermarks] and paper wire; however the later in the process structures caused by calendering or coating and calendering not always give way to visible structures or patterns!
Around 1975 I noticed that all definitives and commemorative stamps of the Netherlands - printed on English paper provided by Harrison and Sons - showed a fine pattern of diagonal lines when held askew against a light source - raking light, oblique lighting (scheerlicht in Dutch) - which I called "glansdiagonalen" or gloss diagonals.
When Googling this term you will get 23 hits for "glansdiagonalen" and they all have to do with my publications!
Raking light is a very good way of detecting watermarks as well!
How well this type of using lighting techniques is known and used in the study of paintings you will see in
http://www-hki.fitzmuseum.cam.ac.uk/ser ... hting.html
to be continued ...
