Seán studied at the School of Printing D.I.T. Dublin and London College of Print. He worked in the print industry for many years and lectured at the School of Printing, D.I.T. before taking up his position at NCAD in 1983.
Sills is a member of the Print Historical Society and a curator and board member of the National Print Museum Ireland. He has conducted workshops for many different organizations including the Paul Getty Foundation U.S., Texas Christian University Dallas, Irish Print Museum,Trinity College Dublin and Dublin City & County libraries. Consultancies include Northern Ireland Trust, Airfield Trust Dublin, Case Project-Leitrim Enterprise Board, Linographics Ltd. Texas.
He collaborated with the National Gallery of Ireland on its first contemporary exhibition of Print ‘Art into Art’, and the Chester Beatty Library for their exhibition ‘The Holy Show’. He has also been commissioned to print numerous limited edition artist books.
Work produced at the NCAD workshop is purchased by the Rare Books Department of Trinity College Dublin and the National Library of Ireland.