Body finishing: Order consensus???

[rotorwrench]

The right mix of aqueous cleaner, phosphoric acid, & phosphate or zinc salts etch solution does more than remove smut and etch the surface of the mild steel. It converts the surface to an inert zinc phosphate which is a lot less apt to corrode. Manganese is also used in some mixtures. Any corrosion that the blasting didn't get off is converted to iron phosphate which is also inert. Manufacturers refer to it as a conversion coat and use it to passivate the surface with phosphates just prior to paint or pickling. Blasting gets most of the corrosion but there is always some left down in the grain of the metal.

 

[51 MERC-CT]

Another thing to consider is how well the lead was laid down. If you paddle it correctly and work it as it should be worked, you lessen the chances of small imperfections, pits, fissures that are hard to clean - only to rear their ugly heads through the paint at a later date.

Truth be told, while we all like the concept of lead as a filler - today it is typically inferior to correctly applied high quality body fillers. Todays 'Bondo' is nothing like the crap from the 50's. Also, over time, there are almost always issues with leaded areas (yes, maybe decades later, but issues tend to surface).

Couldn't agree more. And yes, I remember the first 50's 'BONDO'.
Never used it, but recall that it was as hard as a rock and it had no flexibility. Because of the expansion an contraction of the steel it was applied to, it would, in a short period of time, fall off.
Did fix a bunch of stuff done by others, the right way.