Art provenance research tools:
The Cologne auction house of Lempertz was included in the Art Looting Investigation Unit Red Flag list of names in 1946. In recent times, the name has appeared in connection to several claims for restitution of artworks. Until recently American museums published artworks that had gaps in their provenance 1933-1945 in a database called NEPIP (Nazi Era Provenance Internet Portal) (https://www.aam-us.org/programs/the-nazi-era-provenance-internet-portal-nepip-archive/)
This video shows artworks gathered from NEPIP and other sources that mention the word "Lempertz" in the provenance published by museums.
Note: Some of the mentions concern the German auction house. Some do not. Some concern transactions prior to 1933, others after 1933. Inclusion on the list does not mean that the artwork was looted or sold in a forced sale, only that it contains a specific word.
Link to database used in video: https://public.flourish.studio/visualisation/9769949/ (Enter the word or name you want to search for in the box)
German sales catalogues published by the Getty Provenance Index and Heidelberg University tend to stop or peter out after 1945, so it is very difficult to use digital tools to analyze Lempertz and other auction sales in the 1950s and 1960s and 1970s when Nazi looted artworks were laundered via auction houses with little scrutiny.
Gathering mentions of Lempertz (and other auction houses) in museums provenances is one workaround for this lack of transparency.
Link to Getty Provenance Index
https://www.getty.edu/databases-tools-and-technologies/provenance/
Link to CSV file downloaded from old Getty GPI for search on Lempertz
Link to Heidelberg University German Sales catalogues
https://digi.ub.uni-heidelberg.de/en/germansales//recherche/volltext.html
(photo credit from MFA, Boston museum, The Cumaean Sibyl Donato Creti (Italian (Bolognese), 1671–1749) about 1730 ACCESSION NUMBER 1984.138 PROVENANCE November 23-25, 1983, anonymous (German private collector) sale, Lempertz, Cologne, lot 1482. 1984, sold by Piero Corsini, New York and London, to the MFA. (Accession Date: April 11, 1984) https://collections.mfa.org/objects/34617/the-cumaean-sibyl
