Under what circumstances? Is the nominal coating thickness the same? In general, galvanneal will generate a dull reddish-brown appearance when exposed to corrosive environments, especially near the sheet edges, that is different from conventional iron oxide (red rust). For this reason, if the cosmetic appearance is a requirement for the application, hot dip or electrogalv are used instead. Galvanneal is best for applications that will be subsequently painted and/or spot welded.