Edie–Can you tell us more about these sculptures? Are they currently painted and the paint has worn away? Or were they originally coated with anything? Do you know whether the artist intended the sculpture to age and rust? This document gives a good overview of outdoor sculpture care and some of the particular issues with steel:
http://www.gsa.gov/graphics/pbs/GSA_FineArts_2_Sculpture.pdf
But tell us more and we can see if a sculpture conservator to weigh in!
