National Geographic : 1967 May
W. HERBERT,WESTERNWAYS; )MES BYHELGATEIWES© N.G .S . Hohokam triumph the world's first etchings MOST STARTLING artistic achievement of the Hohokam was their invention of etching with acid. Centuries before European armorers developed a similar process in the middle 1400's, Hohokam craftsmen learned to fashion delicate designs on sea shells obtained in trade with tribes on the Gulf of California. Coating a shell with pitch in the shape of an animal, they soaked it in a weak acid solution-probably the fermented juice of the saguaro-cactus fruit (upper right). The acid slowly gnawed away the unprotected surface of the shell, leaving a raised design like the hornedtoad (lower right). Shells found in earlier excavations had led archeologists to surmise that the Hohokam had discovered etching; the theory found dramatic proof with the discovery of an artifact still wearing a coat of pitch (above, left). The shell had never reached the acid bath. Sevenfold enlargement of another shell shows fine detail of a stylized snake design etched along its outer rim i KODACHROME FROMARIZONA STATEMUSEUM© N.G.S.