Van Dyck's paper
In her catalogue Maurquoy-Hendrickx (L'iconographie d'Antoine Van Dyck, Brussels, 1956) faithfully listed the watermarks of all the impressions of the etchings and the engravings for the Iconography that she encountered, with accompanying illustrations. Unfortunately, they do not help to date the etchings accurately, but because so many different watermarks appear, they show that the printers had a range of paper in stock. Some of the impressions in the Fitzwilliam Museum's collection have beautifully clear watermarks, while others are fragmentary or indistinct. To facilitate future investigation they are noted in the handlist available to download. Below are three spectacular examples that appear on early impressions from the Museum's collection:
Two interlaced Cs with a cross of Lorraine, surmounted by a crown
Joos de Momper, Paul de Vos, Pieter Brueghel, Frans Francken and the self portrait
A double-headed eagle
Jan de Wael, Paulus Pontius, Justus Sustermans and Willem de Vos.
A phoenix in a laurel wreath
Lucas Vorsterman and Erasmus