In his years of training in Paris, Wuerpel became a friend of painter James Abbott McNeill Whistler who helped spread the influence of the "Tonal School" in the Midwest.
He was an outstanding student and graduated from the Manual Training School and was awarded the Selew Medal for the highest four-year average.
Wuerpel was instrumental in developing aesthetics for dentists and he lectured at the Angle School in St. Louis, New York as well as New London, Connecticut and Pasadena, California.
In Paris he became close friends with James Abbott McNeill Whistler, the expatriate American painter and eccentric raconteur.
Whistler wrote to his sister Beatrice of him: "As I told you this morning Wink, poor Mortimer seems to have had rather a cold time of it with this spoil he meandered back from Wuerpel's country with!
wont we Chinkie"[7][8]In old age he recalled that Whistler had requested that his painting "Nocturne: The Solent" hang next to Wuerpel's at the Paris Salon.
[9] Wuerpel had a reputation for being an interesting man and he also became acquainted with Rodman Wanamaker, Sarah Bernhardt and Whitelaw Reid.
John Wanamaker, Rodman's father and the founder of the famous Philadelphia store of that name was one of his first clients and he purchased a painting in 1894,[10] the year that Wuerpel returned home.
[13] Another of his early students was an American woman Wilhelmina Weber Furlong shortly after her arrival in Paris in the late 1890s she abandoned Wuerpel's style of tonalism.
[14] Wuerpel succeeded Ives as director of the School of Fine Arts and went on to teach for 58 years, the longest career of any member of the staff at Washington University.