16 April 2023

Cornelius "Kor" Postma (Part One)

by Claudia Hofstee

Note: This is a two-part essay by Claudia Hofstee. Part One addresses Postma’s life story and Part Two is a detailed look at his involvement with looted art, especially with the Adolphe Schloss Collection.

Cornelis "Kor" Johannes Postma (1903-1977) was a Dutch surrealist painter who participated in the valuation and sale of Nazi-looted art during the German occupation in Paris. During WWII, he served as an expert for the German and French authorities. His involvement is well known with the valuation of the Adolphe Schloss Collection that he performed for the German and French authorities. The full extent of his wartime role in acquiring and selling looted artworks from French collections to German clients is still not clear.

Cornelis Postma was the son of Gerardhus Postma and Joanna van Doorn. He grew up in Hilversum (Netherlands). In 1923, Postma taught himself how to paint close to his hometown, in Laren. Later on, he received art lessons from the Flemish expressionist painters from Joseph Coutré and Gustaaf De Smet (1877-1943). The latter lived in the Netherlands from 1914-1922, He was also a pupil of Dutch artist Willy Schoonhoven van Beurden (1883-1963).

On 21 April 1926, Postma married a Jewish theater actress, Betsy Booleman (1901-1997). The wedding was held in Amsterdam.  A daughter, Heddy Ly Postma (1929-2017), was born three years later. While in Amsterdam, Postma worked for art dealer Pieter de Boer. In the 1930s, he collaborated in group shows with artists like Carel Willink (1900-1983) and Pycke Koch (1901-1991). However, due to disappointments in his career, Postma moved to Paris in 1939 where he worked as an artist until the onset of the German occupation in June 1940.

During WWII, Postma lived in a small family guesthouse at the Hôtel de Nice at 4bis, rue des Beaux-Arts (Paris). The street was known for its many galleries, bookstores, publishers and artists' homes. Postma changed gears and participated in the booming wartime Parisian art market. He befriended some notorious individuals such as art dealer Jean-François Lefranc, responsible for aryanizing Jewish-owned galleries and businesses in and around Paris. Lefranc was a close advisor to Louis Darquier de Pellepoix (1897-1980), Commissioner General for Jewish Affairs under the Vichy regime (1942-1944). Lefranc introduced him to Dr. Bruno Lohse (1911-2007), a Nazi art historian who served as deputy director of the Einsatzstab Reichsleiter Rosenberg (ERR) in France and coordinated anti-Jewish plunder for the ERR. He also met Kurt von Behr (1890-1945), Lohse’s superior at the ERR who supervised the ransacking of Jewish residences from 1942 to 1944 (M-Aktion). Postma’s knowledge of Dutch art and the Dutch art market made him an asset in Lohse’s network of French, German and other informants who persecuted Jewish collectors and dealers.  

Postma’s clients included art dealers like Munich-based Maria Almas-Dietrich (1892-1971) and Berlin-based Hans W. Lange (1904-1945)  to whom he sold a number of looted works. Lange used Postma to facilitate the export of paintings from France to Germany.  In July 1944, Postma exported three paintings; a landscape by the 17th century Dutch artist Jan van Kessel and two pictures by French artist Jean-Étienne Liotard (1702-789), Still life with pitcher and glasses (whose attribution was questioned) and Still life: Tea Set, which is part of the J. Paul Getty Museum in Los Angeles. 
Still Life: Tea Set, by Jean-Etienne Liotard

Still life: Tea Set was consigned to multiple French galleries for which Postma acted as a go-between with the actual seller. Michel Martin (1905-2003) curator at the Musée du Louvre, denied Postma his application for an export license for the Liotard painting mostly because the Louvre was keen on acquiring an important Liotard painting. This rejection of the export license illustrates one way by which French museums exercised their pre-emption right in the 1940s – a right granted to them by the Export Law of 1941. Despite Martin’s opposition, the painting left France in July 1944. Furthermore, Postma dealt occasionally with German art dealer Hildebrand Gurlitt (1895-1956), well-known art expert who had acquired thousands of works of art in occupied territories of Western Europe, mostly in France. 

After the war, Postma remained in Paris where he married his second wife, the Dutch artist Pieternella Wilhelmina (Lili) Bosman van Leer (1905-1966). Her first husband (1941-1949) was Oscar van Leer (1914-1996), a successful entrepreneur. Postma may have met Bosman through Oscar van Leer since Postma was acquainted with van Leer since the 1930s. This connection proved beneficial to Postma's postwar career especially since Van Leer had developed social ties with Princess Beatrix (1938-), crown princess of the Netherlands, and her husband Prince Claus (1926-2002), while organizing gatherings for artist and writers at their estate of Castle Drakensteyn. In the 1970s, Postma gave drawing lessons to Princess Beatrix's children: Willem-Alexander (1967-), Friso (1968-2013) and Constantijn (1969-).

Postma and Lili Bosman regularly had opportunities to hold joint exhibits in Paris as with Galerie Kleinberger in 1951. Postma also enjoyed solo shows at Galerie Vendôme in 1957 and 1958.



NARA RG 239 M1782 roll M1782_10F1
NARA RG 239 M1944 rolls 22, 44, 47, 52, 95
NARA RG 260 M1941 roll 19
NARA RG 260 M1949 roll 6

Archives Nationales (AN), Pierrefitte, France
AN, 20144657/6, 06 July 1944, n. fol.
Z/NL 381, 8841 (C), 379, Postma

Archives du Ministère de l’Europe et des affaires étrangères (AMAE), La Courneuve, France
Séries 370-555 Série P: archives de provenance diverse
209SUP/406: Cornelius Postma
209SUP406p48: Cornelius Postma
209SUP/482 P166 : Cornelius Postma
209SUP/482 P167: Interrogatoire Hermann Voss

Stadsarchief Amsterdam, 30561: Archief van Oscar van Leer 1920 – 2003

Noord-Hollands Archief, 358.6 burgerlijke stand van de gemeente Amsterdam, inv. nr. 2858, aktenr. Reg. 2A fol. 50v; inv. nr. 3105, aktenr. Reg. 1B fol. 46v

Published sources:

Elisabeth Furtwängler and Mattes Lammert, Kunst und Profit: Museen und der französische Kunstmarkt im Zweiten Weltkrieg, 2022

Vanessa von Kolpinski, ‘Art Transfers from France During and After the Occupation: On Export Regulation as a Protective Measure and Resulting Source Material’, Arts et politiques, 2022: 138-155]
-self-taught Postma

P.M. J. E. Jacobs, Beeldend Benelux: Biografisch handboek, vol. 4, Tilburg 2000, p. 668.

Jean-Étienne Liotard, Still-life: Tea Set, c. 1781-83, Los Angeles, J. Paul Getty Museum, inv. no 84.PA57.