It is very important that the parts be perfectly clean, even at the primer stage. After being wiped clean with a paint prep solvent, the parts are wiped with a clean tack cloth, and blown with filtered compressed air.
Skinning And Fitting
The left front door of the g/28 was rough enough for Alan to decide a new skin from Classic Industries would be better than repairing the original. Like all the panels from Classic, the door skins came with a durable E-coat finish. Alan says: "We strip the E-coat off the exterior of the panels in the process of working the panels to the level we're after, and once the bodywork is done, we put etch primer over the bare metal. If it's a good E-coat finish on the reproduction parts like these, we'll leave it on the inside of the panel. If it's an aftermarket part with some kind of lacquer primer, we'll strip that and put an epoxy on it."
Alan detailed the door skin installation: "To separate the original skin, you just grind all around the flange, on the outer extreme edge where it folds over, and then just grind the welds with a cut-off wheel in a die grinder to separate the flange. The inside of the door frame is retained, and it has to be clean of any rust; we sandblasted these to get the frames clean. The frames are hammered straight, and we have some specialty tools to put the door skins on. The door skins get the flanges rolled over on the edge, but nothing is welded, at this point, until the sheetmetal is fitted to the car. Usually you have some adjustment in the skin to the frame, so to do it properly, it needs to be put back on the car and fitted to everything before you start welding the new skin to the door frame. There was a good bit of time spent fitting the panels on this car, starting with the doors to the quarter and rockers, and then the front sheet metal to the doors. One of the most important things you can do is fit the panels, because if it's not fitting now, you're going to be in trouble later. Whatever you have in the trial fitting of the panels is what you're going to end up living with."
The opening round of primer is Sherwin-Williams etch primer, which is formulated for a strong bond to bare metal.
Filling
With the metalwork done, it's time for the final filling with body filler. Even the new panels are fully checked and any minor flaws are corrected. Alan was going for perfection on the body with the g/28 project, and told us: "A lot of people wouldn't go through this much trouble to get these panels as straight as they are; I mean GM didn't when the car was new. On the new panels, a lot of times we'll use the E-coat as a guidecoat and block over the panels and anything that we can see that stands out in the stock E-coat we can go in and do some hammer, dolly, and fill work in those areas."
Two or three coats of Sherwin-Williams urethane primer filler are next. The trick is to apply enough of this surfacer to allow block sanding to perfection without piling on excess thickness.
"We just take the E-coat off in those areas where we know we need to do bodywork and at that point, the hammer and dolly work is done and gets a coat of filler wiped on it. If it's something just minute, we would just work it off with No. 80 grit on the air file or long-board. Anything that needs signifi-cant work would get the 8-inch orbital sander, then air files, and then hand-finished with the long-boards. If the filler is just a light wipe on something, you would just go with No. 80 grit and then finish with 180. If it's got a good bit of work to do, you'd start with 40, then 80, and then finish with 180 for primer. Once the first go-around is done, the rest of the E-coat is block-sanded from the new panels with 180 grit, again using it as a guidecoat to see if anything else shows up."
Alan continues: "We finish all of the body filler with 180 grit. That way we can put two to three coats of the filling primer on it and not cheat by putting too much primer on. All you are doing with a rough finish on the filler is causing more work later and then you are building a finish on the car that's not going to be as durable. You're going to get shrinkage and a more brittle surface because you'll end up having more material on it. These new Classic Industries parts didn't need a lot of work to get them where they needed to be and they were probably about as good as it was from GM when the cars were new."
In The Booth
Once all the metalwork is done, the panels are filled and finished to 180 grit, and the panel fit is checked and checked again, it's time to move into the booth for primer application. Alan shoots all of the removable body panels separately from the main body tub. This way the color coverage in the final assembled vehicle is seamless with no tape line inside or out, and full coverage of paint is obtained, even in blind areas or at the flanged panel joins. Alan: "That's the only way to get a good finish on the car without tape lines. If you jamb the car out, then you've got tape lines on the edges of the doors and the quarters. With the customers we have, that just isn't the kind of quality they are looking for."
The main body tub is masked, then cleaned and primed with the same process as the loose panels, starting with the etch primer and then building the surface with the urethane filler. | 
A final step in the booth is to apply a contrasting layer of guidecoat to the primered surface. The guidecoat will show surface flaws as the panel is being block sanded. The first cut is fairly aggressive, using 180 grit dry paper. | 
Notice how the guidecoat reveals a low spot at the character line near the edge of this door? The low area, with adjacent primer cut all the way through, indicates more work is needed here. |
Blocking requires technique and patience. Here, a paint paddle wrapped with sandpaper is used to block a door, working with a diagonal sliding action up to the character line of the panel from one side at a time. | 
Back in the booth after a thorough cleaning, the panels are shot with a coat of Sherwin-Williams urethane sealer, followed by three coats of their Ultra 7000 line of Garnet Red Mica basecoat (AMC code 3C, a color used on '83-86 Jeeps). | |