# Which blowups of a smooth surface are smooth?

Say $X$ is a smooth algebraic surface and $Z$ is some subscheme. When is the blowup of $X$ along $Z$ smooth?

-
I don't think that there is a straightforward answer to this question, see mathoverflow.net/questions/21232/when-is-a-blow-up-non-singular/… –  Blup Jan 30 '12 at 9:19
On a smooth surface, it is always smooth if $Z$ is reduced... For non-reduced $Z$, the link Blup provided is useful. On the other hand, there is Zariski factorization of complete (integrally closed) ideals through which the surface question should be more or less tractable. –  Karl Schwede Jan 30 '12 at 15:10