Understanding Frank Zollner's Work on Leonardo Da Vinci
The big project everyone needs to know about is Zollner's Leonardo da Vinci: The Complete Drawings. It came out around 2018 from Taschen, and it's essentially a massive critical catalogue raisonné of everything Leonardo did on paper. He and his team went through every single sheet — some 300 plus drawings — checked provenance, looked at watermarks, dated them, and reassigned authorship where previous scholars had gotten it wrong. What makes this different from older catalogues like Pedretti's or American ones from the 70s and 80s is that Zollner had access to infrared reflectography and other imaging tech that simply didn't exist when those earlier works were compiled. He also spent years in archives across Europe looking at attribution disputes that had been sitting unresolved. The result is a book that looks like a coffee table book from the outside but is really a serious scholarly reference work. It runs about 600 pages with full-page reproductions and detailed notes on each piece. If you're doing research on Leonardo's drawing practice, start with this rather than flipping through older sources. The attributions have shifted substantially, and several drawings long considered autograph were pulled off the list while others were added. The British Museum, the Royal Library at Windsor, and the Louvre collections all got re-examined under this framework.
Here's a practical problem I ran into. I was cross-referencing a drawing attributed to Leonardo's workshop in an older publication against Zollner's catalogue, and the catalogue number had been completely reorganized from the previous system. The worksheet I was tracking under a different number in the earlier literature ended up listed elsewhere. What I found worked was to use the museum and inventory number as the primary key rather than relying on the Zollner catalogue number alone, since the new numbering doesn't align neatly with any prior system. Most library databases now let you search by museum accession number, so keep that in mind if you're doing academic work. There are two things beginners miss about Zollner's approach. First, he separates the surviving drawings into autograph, collaborative, and workshop categories more rigorously than most earlier scholars did. That means a drawing labeled "Leonardo" in an older book might actually be listed as a workshop copy in Zollner, and vice versa. Second, the dating range he assigns often stretches wider than you'd expect. Leonardo kept returning to compositions over decades, and Zollner acknowledges that with certain sheets the date range can span fifteen to twenty years depending on the evidence available. The main limitation is that the catalogue is print-only with no open-access digital version. There's no searchable database you can query, no high-resolution images with zoom, and no API to pull data from. If you're doing quantitative analysis or building a dataset, you're stuck with manual transcription. I've seen people spend weeks entering catalogue data by hand because the images inside the book aren't available online in any systematic way. The only workaround is to photograph the relevant pages yourself and build your own lookup table, which works but is tedious.
For attribution questions, Zollner also relies heavily on connoisseurship rather than hard scientific data. Infrared results help with underdrawings, but the final call on whether a sheet is autograph or workshop still comes down to stylistic analysis. That's honest of him to admit, but it means two scholars can look at the same drawing and disagree, and Zollner's authority won't settle it definitively. When I hit those disagreements I usually go back to the original photographic plates and the condition reports rather than accepting the catalogue label at face value. Another thing worth noting: Zollner's work doesn't cover the paintings in the same depth. His focus is drawings, notebooks, and scientific manuscripts. If you're looking for a comprehensive study of Leonardo's painted works you'll need to supplement with other sources like Carmen C. Bambach's work at the Met or Martin Kemp's publications. The Zollner catalogue is definitive for the drawn output, nothing more. The book is expensive new, usually around two hundred dollars at retailers. Used copies float around for less but condition varies on the plates. Some university libraries carry it, and if you're doing serious work the interlibrary loan route is worth exploring since the content takes time to absorb regardless. There's no lighter companion volume either, so if you need something portable for reading room visits, you're stuck carrying the whole thing.
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