Yves KLEIN (1928-1962). Blue postage stamp, IKB pigment (2.5 - Lot 79

Yves KLEIN (1928-1962). Blue postage stamp, IKB pigment (2.5x2cm) on an envelope addressed to A. Chicont in Paris, with postmark PP May 25, 1959, and Return to Sender and Does Not Live at Address stamps. The envelope contained the invitation card (enclosed) for "the two papers given on the theme of L'Évolution de l'Art vers l'Immatériel by Messrs. Yves Klein and Werner Ruhnau architecte" on June 3 and 5, 1959 at the Sorbonne. In 1957, Yves Klein decided to present his "bleu immatériel" at the Iris Clert gallery. The artist used the color blue on an everyday object, including a stamp, giving it the status of a work of art. It wasn't until 1960 that the chemical formula for this ultramarine blue was registered with the Institut National de la Propriété Industrielle, under the name IKB (International Klein Blue). These "blue stamps" were used as postage stamps for invitation cards to his exhibitions at the Iris Clert and Colette Allendy galleries in 1958 and 1959. The organizers paid the postage directly in cash to the post office for all mailings. Each invitation card was then stamped with an IKB "blue stamp". The postage-paid No. 1 date stamp refers to the Central Post Office in Paris, the only one where mail franked with original stamps could be sent. Some forty postcards or envelopes franked between 1957 and 1959 are currently known.