While the RRP began with good intentions and with well-respected experts on staff, nevertheless there were troubles from the start. The volumes that list different findings in regard to works accepted and rejected in attribution to Rembrandt is a testament to this. In the earlier volumes, some paintings that were listed as not being true Rembrandt works were in the later volumes re-examined and their findings revised and overturned. An example of this was The Self Portrait, which was dismissed in the RRP’s first book in 1982 and later reinstated.
Four full-length volumes of the Corpus were published, followed by a smaller fifth volume. In all, the RRP initially accepted a total of 250 paintings as being works by Rembrandt, doubted or rejected 162 as not being his, and, in later volumes, overturned 70 re-examined works. A remaining 80 paintings were not cataloged, which is a quarter of the collection. Those are to be included in a summary volume.
Reasons for the RRP’s troubles and why the books differ, vary. One of the biggest was the tension among its members and their difficulty early on to establish agreeable research methods for authenticating Rembrandt paintings, calling it their “authenticity problem.”
For example, they could not agree upon whether to use scientific methods. They stated, “using x-ray and other radiographic methods, experts on the analysis of grounds and other paint samples, and the analysis of wood supports and canvas [had] demonstrated that, so far, the results of these research methods applied to Rembrandt had yielded little of significance for the determination of authenticity.”
In a cited example, the RRP stated they long considered The Hague Bust of an old man in a cap to be a later imitation. Its wood panel, however, turned out to have come from the same plank as the panels of the Hamburg Simeon in the Temple and the Berlin Minerva, creating a high degree of probability that the works were painted in the same workshop because they came from the same tree-trunk. And with the Braunschweig Portrait of a man and Portrait of a woman, they were also initially considered as later imitations, but the panel of the woman proved to have come from the same tree as the center plank of the Chicago Man in a gorget and black cap.
The RRP also discussed whether it was even possible to view paintings as a group: “At an early stage, the question was raised by the RRP’s critics whether a ‘collective expertise’ was in fact possible. However, the late 1960s and 70s was a time of great belief in teamwork generally, although it gradually became clear that actual sharing of visual experiences–let alone communicating them–is virtually impossible.”
The RRP’s investigation practices were an issue as well. In their final full-sized book, volume IV, the RRP argued that while “in theory it may sometimes be possible to prove that a painting is not by Rembrandt by means of technical investigation, the converse–using the same methods to prove conclusively that a painting is certainly by Rembrandt–is never possible. It may be redundant to labor the point that, on the one hand, historical works of art are complex man-made objects whose materials, manufacture, as well as style and quality can vary even when made by the same person, while on the other hand works that are closely related in just these respects could have been done by different painters, e.g. in Rembrandt’s immediate circle.”
The RRP even debated the order in which the book was to be laid out, chronologically or thematic, in which the last volumes were dramatically changed . “Having opted for a chronological approach to the cataloging of Rembrandt’s paintings in the first three volumes, it was decided in 1993 to adopt a thematic approach for further volumes. This was largely to facilitate the recognition of different hands. The new approach yielded much more information not only about Rembrandt’s working methods, but also about the function and meaning of his works.”