Cecily Sash was a founding member of the famed Amadlozi Group, along with Cecil Skotnes, Edoardo Villa, Sydney Kumalo and Giuseppe Cattaneo, represented by gallerist Egon Guenther. She trained under Maurice van Essche at Wits Technical College Art School and later studied in London with Henry Moore at Chelsea Polytechnic and Victor Pasmore at the Camberwell School of Art.
Sash taught at Jeppe High School for Girls and lectured for nearly 20 years in the fine art department of the University of the Witwatersrand in Johannesburg and, according to the art historian Esmé Berman, “few South African artists of her generation exercised more influence”. She later settled in Wales in the early 1970s.
She exhibited regularly both in South Africa and abroad, and took on a number of prestigious commissions including major mosaic murals for the Transvaal Provincial Administration Building (1963) and Jan Smuts Airport (1968). She showed work at the São Paulo Biennale (1963 and 1967), as well as the Venice Biennale (1964), and moved comfortably between linear objectivity, material experimentation, and bold, decorative abstraction.