Ballantine has specialized in all aspects of the work of Donald Judd since 1969, from fabrication, restoration, curating, and research to sales and fundraising, nationally and internationally. He first met Judd in February 1968 while a graduate fellow at the Whitney Museum's Independent Studies Program where Judd was a lecturer. From April 1969 until Judd died in February 1994, Ballantine fabricated more than 200 of Judd's works directly and approved a large number by other fabricators on Judd's behalf. He organized Judd's Memorial at the University Club in New York in May 1994. In 1997 he co-organized a two day symposium on Judd restoration issues in New York. Between 1994-2004 he was Art Supervisor of the Donald Judd Estate/Judd Foundation. Since 2004 he has curated Judd exhibitions in London, Cologne, Basel, Madrid and New York (2). From 1969 to the present Ballantine has restored more than 2000 Judd works in all materials. He works as an independent Judd restorer, curator, researcher, lecturer and writer and is preparing a Judd drawing show (London). He lives in New York.