When I was in the trade our painters used Glasurit etch primers. There was a red oxide colour they used for steel. A yellow colour for aluminium (had an additive added before use) and a green epoxy primer which was more durable and a sealer. At home I have used K&H and Transtar brands in an aerosol can that did the job fine. I have seen a self etching hi build primer in the Just Cars mag called 'All U Need'. That would cut back on time and money but I don't know how it is as a product. I like etch for wet on wet applications.
