I have had my 67 SS/RS since 1995 and finally can now work on restoring it. The car has been dry garage stored all these years since life happened along way preventing the restoration. The car is completely disassembled and on a rotisserie.

First issue/question: In 1996 I sandblasted and painted the underside of the body with GM Chassis Black. Over the years, the underside is showing a bit of little rust spots here and there. I plan to either hand sand or sandblast the underside again. I have thought about going with epoxy primer (DP 90) and then topcoat. My question is what is the best route for paint on the underside? If epoxy primer, what is the best topcoat?

Second issue/question: I have a panel to replace. Replacement panels these days come with a black coating on them. How do these panels need to be prepped for paint? Do you strip them, sandblast them (carefully), or just hit them with a scotchbrite pad?

Thanks....

 

I guarantee there are members on this forum that know FAR More than me about paint, but I can at least share the process my restoration shop has followed as they restore my ’68 Camaro. I parked mine in the mid-‘80’s and like you, kept it dry, but once they dug into it, oh my…

Everywhere they took paint off down to shiny metal, they IMMEDIATELY sprayed “OSPHO”-brand rust conversion liquid. This was premised on the FACT that bare metal immediately fuses with water vapor in the air to create microscopic rust (iron oxide). I believe I was told that once that dried, they fine-sanded off raised particles that once were rust. After the OSPHO was on, they then sprayed 2 coats of an acid-etch primer, to serve as a binding surface for the high-solids “Direct to Metal” layers of primer that followed.

In the case of the street-side of the pan and wheel wells, they then sprayed truck-bed liner, and that is the surface that is exposed to road nastiness such as salt and rock chips. Not sure if this went on over the acid-etch primer directly or went on over DTM primer. My entire pan was replaced from bottom of firewall to front of trunk bottom.

Regarding panels, I was told they would only scuff-sand them before going to at least one coat of DTM primer, and once they were satisfied (in general as well as replacement panels), they finished their prep with two coats of black sealer. This was to protect the ‘fragile’ surface of the DTM primer from scratches and moisture, and to provide a uniform color under the coats of base color. Feel free to listen to any comments that follow, as my understanding about paint is there are a near-infinite number of ways to do the job, some ending in perfection, some in catastrophe, and some somewhere in between. Also, not all paints (base and clear) are created equal in quality...

This is just the process my shop followed, to the best of my knowledge.

 

Thanks for the info. I think I will blast off the GM Chassis Black and redo it with DP90. Just have to decide on what topcoat.