13:20-49C.42 Undercoating
(a) The entire underside of the bus body, including floor sections, cross member, and below floor line side panels, shall be coated with rustproofing compound for which the compound manufacturer has issued a notarized certification of compliance to the bus body builder that the compound meets or exceeds all performance and qualitative requirements of applicable Federal specifications.
(b) Undercoating compound shall be applied with suitable airless or conventional spray equipment to recommended film thickness and shall show no evidence of voids in cured film.