Manfred Wedemeyer wrote the following in his book, "Codgers, Artists, and Connoisseurs – The Hidden Side of Sylt" (Pomp & Sobkowiak, Essen 1986, p. 118)

Franz Korwan: One of Four Jews Living on Sylt
"The Jewish part of the population of Sylt was always small. The 7,521 inhabitants in 1933 included only three Jews, who lived in the town of Westerland, plus one more who lived in Keitum. Their number had not changed since 1905; only these few Jews made their home on the island.  Nevertheless, once Westerland was discovered as a seaside resort, Jewish influence in international tastes for seaside resorts of the Wilhelmine era played no small role. For numerous Jews were to be counted among the guests of this summer resort, as can be gathered from the resort lists, and a number of these opened seasonal businesses in Westerland.
Already before 1900, the Jewish painter Franz Korwan-Katzenstein (born in 1865 in Heinebach near Kassel) had opened a studio on Strandstrasse (Beach Street) of the island metropolis. He was a student of Eugen Dücker at the Düsseldorf Academy and had attended Eugen Bracht's master class at the Berlin Academy.  On Sylt he was often together with Eugen Dücker before settling permanently on the island. His Westerland studio was visited by prominent resort guests, including Heinrich von Stephan, the organizer of the German postal system. In 1896 the General Postmaster had posed in Korwan's studio as a model for the production of a bust by the sculptor, Hugo Berwald, of Berlin. After Stephan's death, a committee was formed in Westerland to make preparations for a memorial for the deceased, and Franz Korwan was one of its members. For some time he was also a member of the Board of Directors of the Steamship Navigation Company of Sylt. As a member of the town council he participated actively in the local politics of the Westerland community.  In Berlin he negotiated  successfully with the Prussian Ministry of the Interior for Westerland to be chartered as a town in 1905.
Two paintings by Korwan-Katzenstein are in the possession of the Federal Mail Museum in Frankfurt am Main, including the oil painting, "Transporting the Mail Across the Ice to Sylt 1892." In 1908 the artist restored the interior spaces of the Old Friesian House in Keitum, and in 1913 he painted  the Church of St. Severin in Keitum. In the 1920s Korwan worked in a studio in Keitum in the house of the Jewish family of Julius Saenger, who was buried according to Jewish ritual in Keitum in 1929. A Japanese stone lantern decorates the grave of this man, who was the co-owner of an export business in Hamburg that still exists today, and which deals primarily in trade with Japan.
Franz Korwan left the island of Sylt around 1936 and went to Baden-Baden.  From there he was deported to southern France, and perished in the Pyrenees in 1940."