Ad Reinhardt, by Lucy R. Lippard. New York: Harry N. Abrams. 216 pp. $65.

Anyone who still thinks of Ad Reinhardt exclusively as the creator of solid black paintings would do well to read this book. Not only will he find out that these paintings weren't really all black, he will also discover that Reinhardt was actually a brilliant and subtle colorist. To say nothing of what he will discover about the artist's talent for words when discussing the art field in general or his own work in particular.This book traces Reinhardt's evolution as an artist from his early days in the 1930s, when he was a fairly typical abstract painter, to the 1950s and '60s, when he reigned as one of the leading figures of American art.This development is all clearly spelled out for us in Lucy Lippard's incisive and oddly affectionate text, which is still among the best essays we have on Reinhardt. And in a large number of excellent illustrations - many of them in color - which are remarkably faithful to the originals. Even the late ''black'' paintings come across quite well - at least the reader gets a fairly good idea of what they are all about.This may be a bit too specialized a book for the general reader, but it is highly recommended to anyone particularly interested in post-World War II American art.