Jim Smart
March 26, 2019

Preparing a Mustang for paint is hard enough when you plan to keep the same color. When you’re planning a color change, prep becomes a lot more involved because there are additional steps you must take. For one thing, you have to mask more areas than you would if you were keeping the same color. And honestly, we’d like you to think more about close attention to detail when it’s time to paint your Mustang. We see so many examples at shows from coast to coast of how not to paint a Mustang. You need to strip the car down significantly if you’re going to do this well. Head and taillight modules, trim, weatherstripping, trunk liner, cowl molding, and the rest must be removed to ensure that all areas get painted properly.

We are at AR Auto Body in Lancaster, California, with an Oxford White 1999 Mustang GT that needs a little love. This is but the beginning of a huge transformation for this tired two-decade old New Edge ride. We’re going to strip and repaint it, and then fit it with a killer 5.3L SOHC Modular mill that will demonstrate what you can do with this dated overhead cam powerplant. We’re expecting 700-plus horsepower with boost. Our New Edge Mustang will soon emerge into the morning light a changed Pony with new paint and a fresh attitude with hot 16-valve Modular power.

First order of business at AR Auto Body is the striptease—taking this thing down to the bare body, masking the areas we don’t want painted, and scuffing and perfecting the surfaces we do want painted. A good paint job requires good prep. You must stay with prep work until the surface becomes perfect. No low spots or high spots no matter how small. Even the smallest imperfection will show up in the finish.

Do the prep work yourself to save a bunch of money at the body shop. You must be both patient and tenacious. That means staying with it until you have achieved a perfect surface. No dents. No irregularities. No low spots nor high spots. Surfaces that are dead perfect.

To get a perfect surface, you must be able to feel irregularities with your fingertips. Some of us come by this naturally; others struggle. You have to be able to feel flaws as well as see them. Flaws are found with long, medium, and short sanding boards, which find the high and low spots as you sand. Low spots get filled with body filler and sanded until they are flush and undetectable. High spots have to be worked flush with a body hammer and dolly.

Body filler alone is all about chemistry and getting filler and hardener in the correct proportions. Too much hardener and the filler cures too quickly and becomes brittle. Not enough hardener and the filler never cures. You have to get this right. You must also have compatible primer and paint. Think of primer as the first coat of paint. It provides a solid foundation for the top coats. This means you must follow the manufacturer’s instructions to the letter. No cheating. No cutting corners. If you’re trying to save money, this isn’t the place to do it. Paint is very expensive. If you have to redo the whole paint job later, how much money did you save? Get it right the first time.

We’re going to show you professional body prep as performed by AR Auto Body. These guys are artists. They know how to perfect a body and get it ready for paint. They’re patient and tenacious. They stay with it until they get a perfect surface. Let’s get started.

To knock a New Edge apart, you need tools of the trade, the same tools used at the best shops: a complete set of metric sockets, extensions, and a 3/8-inch ratchet, trim removal tools, open/box-end wrenches, and Phillips and Torx drivers. You’re also going to need plenty of no-bleed, paint-specific green 3M masking tape, duct tape, and masking paper and plastic to protect areas from dust and overspray.
When you change paint color, expect a tremendous amount of work removing everything imaginable from the body. The entire trunk liner needs to be removed along with every single piece of weatherstripping. This is something you can do yourself before taking your Mustang to the body shop.
Everything must come off, including taillight, headlight, and parking light modules. They’re secured with studs and Tinnerman nuts inside the body. Sometimes they just pop out. Be gentle with them.
Headlight modules on the New Edge are secured with the headlight adjusters. They’re easy to pop out and disconnect.
The fascia should be removed when you’re changing color. You want all parts of the body ready for paint, including what you cannot see. This 2003-2004 Cobra fascia has been on for over 15 years, and it shows. The good news is we’re planning to replace this with a fresh fascia from National Parts Depot.
Weatherstripping is easy to remove and reinstall. Because these New Edge Mustangs are getting old, it is suggested you replace the weatherstripping. National Parts Depot can help with trim parts and weatherstripping as well.
Pesky details like the Mach460 speakers and door panels must be removed.
Trim parts and hardware should be bagged and marked. Don’t kid yourself—you’re never going to remember where it all goes. Grab your cellphone and take pictures before pulling it all apart.
Areas where you don’t want fallout from body prep and paint should be masked—and we mean masked to the extreme. Paint overspray is hard to remove, which is incentive to get everything well covered.
Tools of the trade for good body preparation. You need short, medium, and long boards for a broad ranging of sanding duties. You’re going to need 80-, 120-, 240-, 320-, 400-, 600-, and 1,000-grit 3M sandpaper for most of the phases of body prep. Use 80- and 120-grit for the heavy work of leveling body filler and cutting rust. In fact, you can use a cheese grater for that first cut on body filler before going to 80-grit.
Use a long board for sanding broad surfaces like quarter-panels, doors, the decklid, and the hood. The long board covers a broad area, yielding low and high spots. High spots are those that yield primer and bare steel first. Low spots get missed by the long board and need to be filled.
Long and medium boards are used to work broad surfaces like quarter-panels and doors. Note the high spot at the doorjamb (arrow) that’s down to the steel. Low spots and high spots show up when we use the long and medium boards. This particular high spot is a rise in the stamping. As you long- and medium-board the surfaces, move the board diagonally as well as straight to cover all angles.
The short board is more for tighter places, like this area above the door handle. Note that we removed the door handle for paint prep. Also note the high spots that need to be worked and leveled. High spots have to be dollied with a body hammer and dolly until they are flush, then filled as necessary.
High spots look like this and are where we first get down to the base primer and steel.
These are all high spots on the decklid. They need to be dollied and hammered where possible. Sometimes you have to fill the area around these high spots, then work it level.
When all areas have been worked, filled, and sanded smooth with 240- and 320-grit paper, you are ready for a good wet-sanding of the base primer coat. You want surfaces to appear scuffed, which makes for good paint adhesion when it comes time for the final primer coat. Scotch-Brite is also good for that final scuff.
Now that we have crisp surfaces ready for primer-sealer, it is time for body panel fitment. Fenders are mounted and properly fitted, then checked for proper gaps. Gaps should all be approximately 1/4 to 5/16 inch. This is when you fit body panels, not after the paint goes on and you risk damage.
Shims are sometimes use to set body gaps. The 1994-2004 Mustangs were theoretically zero-adjust bodies from the factory. However, Ford was not always perfect, and accidents change everything. If your Mustang has been plowed, chances are you will have to shim a panel to set the gaps right.
With the body wet-sanded and panels gapped we are ready for final prep, which entails a clean tack cloth and compressed air. Always good to perform a wet wipe-down as well to ensure the removal of all dust and debris.
Masking is likely the most tedious aspect of body work. Use only green 3M masking tape. It boasts excellent no-paint-creep technology.
Primer-sealer is laid down first with a light coat for good adhesion to the existing finish. The second and third coats need to be heavier and given plenty of time to cure. These Axalta Cromax finishes are two-part: paint and a hardener. Follow Axalta’s instructions to the letter, and never believe you know more than they do.
The Axalta Cromax primer-sealer coat is allowed to cure, then wiped down with a tack cloth prior to the application of the color basecoat, which must be applied right away.
The Axalta primer-sealer is wet-sanded with 400- and 600-grit paper to scuff the finish before the color basecoat goes on.
This is the way your Axalta primer-sealer finish should look after wet sanding. You want a 100 percent scuff with all of the primer-sealer scuffed and ready for color.
This is exactly what you want here. Note that 100 percent of the finish is scuffed, which will net good paint adhesion.
We look at the doors where they meet the front fenders and wonder what Ford was thinking. This is the toughest gap on the 1994-2004 body to get right, because the angles just don’t work here. If you’re frustrated with this door-to-fender gap you are not alone.
AR Auto Body went to extremes to get body gaps right on this New Edge Mustang. The body is absolutely perfect in terms of gaps and paint prep.
First order of paint basecoat and clearcoat business is the jambs, which always get painted first. Reason behind this is overspray issues. You’d rather have overspray in the jambs then on the surface. This is also a great preview of the new color. When Ford Performance unveiled Liquid Blue, we were enamored by it. Axalta’s solution is its latest Blue Satin Pearl blend.
This is why you cover all the bases with a color change. Areas you cannot see also get painted the new color to where the color change defies detection. In Part 2 we lay down color basecoat and clearcoat, along with color sanding and buffing.

Photography by Jim Smart