It’s time to reach beneith the surface to see what is really hiding under that old paint on your ride. Find out which method is best for you as we delve into the many methods you can do to take it down to bare metal. Don’t rely on other paint protection products just try our car paint protection Adelaide.
Unless your project car has been hammered out of virgin sheetmetal, the first thing to do when considering new paint is figure out how to handle the paint that’s already there.
In some cases, the decision is pretty straightforward. Many painters consider a car’s original finish to be one of the best foundations you can have for fresh paint, provided what’s still on the car isn’t cracking, lifting, or showing other signs of wear or damage. As John Sloane of Eastwood put it, a car’s original finish “was applied with perfect prep and under ideal conditions, so it’s tough to beat.” If that’s the case with your project car, you can feel pretty secure about scuffing the original finish, then priming and shooting right over it.
Then again, how many potential project cars have you run into lately that still sport unblemished, original paint? More likely, the cars you’re looking to buy and build are covered with Lord-knows-how-many resprays over the top of Lord-knows-how-much body filler, questionable patch panels, bad welds, rust, or some combination of them all. And that is definitely not the kind of foundation you want under your spanking-new paint.
If you’re not completely familiar with a car’s history, how can you tell what may be lurking underneath that top layer of pigment? Well, there’s a decidedly low-tech method: Grab a piece of sandpaper, pick a spot on the car — preferably a location likely to have seen some damage over the years, like a rocker or rear quarter-panel — and start rubbing. (A pocketknife will work, too, if you can find a corner to pick at.) It won’t take long before you start revealing layers beneath the topcoat. Read them like tree rings: The more layers you find, the greater the certainty that a scuff job won’t cut it and a strip to bare metal is in order.
If you’re looking for a less intrusive way to judge the integrity of a car’s finish, Eastwood sells a couple of different types of paint-thickness gauges you can use without leaving a mark. Paint-thickness gauges — a magnetic version retails for about $50 and an ultrasonic one with a digital readout will set you back about $350 — are actually not 100 percent accurate, Sloane said. What these gauges do is measure the distance between the paint’s surface and the sheetmetal below (both gauges work only on steel bodies). OE paint will measure between 0.003 inch and 0.005 inch thick. If the measurement you get is more than 0.005 inch, chances are good “there’s something other than paint under there,” Sloane said. That rule of thumb doesn’t apply to custom paint jobs, however, which can measure .012-inch to .015-inch thick or more. But even so, if you’re running into paint that thick, it becomes “less and less desirable to put paint over what you have,” Sloane said. “At that thickness, you can’t assume you won’t develop cracks in the new paint as the different substrates beneath it expand and contract at different rates.”
There is another way to look at the strip versus scuff-and-shoot question. Most of the restoration specialists and high-end rod builders we spoke to prefer to start a paint job with a completely clean slate: bare metal. That way they know exactly what they’re building on as they put together a show-winning finish. So if you don’t own a car with well-preserved, original paint or you’re clearing a place on your mantel for a boatload of car-show trophies, read on to figure out the best plan of attack to get the starting point you need for eye-popping paint.
Paint-stripping techniques generally fall into two broad categories — mechanical and chemical. Mechanical stripping methods utilize some form of abrasive to remove paint from the metal. Abrasives range from good old-fashioned sandpaper to a variety of blasting media.
Do-it-yourselfers will usually default to sanding. Logistically, it’s the easiest method, as the disassembly process is simpler than for blasting or dipping the metal, and you don’t have to transport the car anywhere to get it done. It’s also far less expensive. The thousand or more dollars you’d pay for blasting or dipping can buy a lot of sandpaper, not to mention a new air-powered sander, sanding boards, maybe even a new compressor if you shop smart. (See the “Compressor Tips” sidebar for more info on powering your air tools.)
Yet sanding an entire car, even if you’re doing just the outside, is one of those jobs that’s measured in days, not hours. If there’s a ton of paint on the car, or if the paint is relatively new — and therefore strong — you’re going to be working it awhile, even if you’re using power sanders. And either way, your arms will ache for days afterward. But if you have more time and muscle than money, get out the paper and start rubbing.
One of sanding’s advantages is that you can easily tailor its aggressiveness to the job at hand. If all you need to do is scuff original paint, a light touch with 320- to 400-grit paper should do the trick. If you’re stripping down to metal, the consensus from our paint experts is that 80-grit is a good starting point. If your car’s finish is particularly stubborn or thick, stepping down to 40- or even 24-grit paper will help cut the tough stuff. Take care, though, as it’s very easy to gouge the metal when using paper that rough.
A power sander, whether a rotary or a dual-action (DA) sander, will cut your sanding time and effort considerably. A rotary sander generally spins faster than a DA, so it does offer more paint-cutting power, but there’s a risk of burning rather than removing the paint if you’re spinning the abrasive too fast. Burning the paint will, at best, clog your paper and waste material, and at worst, generate enough heat to warp the sheetmetal.
In some cases, you can remove paint more quickly by peeling it up with a razor blade than by rubbing it off with a sander. Jerry Sievers of Paint n Place told us he’s seen entire race trailers stripped not with abrasives but with razors. This can be especially effective if the paint you’re removing wasn’t applied well in the first place. If you catch an edge of poorly prepped paint with a razor, it’ll come off in sheets.
It’s a Blast
Media blasting is an amazing thing to watch. Layers of paint that would take days to sand off simply vaporize at the end of a high-pressure nozzle. Depending on the medium used and the nozzle’s line pressure, blasting can be gentle enough to strip wood and fiberglass or aggressive enough to cut through body filler and even rust.
If done improperly, however, media blasting can do more harm than good. Blast sheetmetal too hard, for too long, or with the wrong medium, and you’ll warp panels, either because the impact of the medium is stretching the metal or because excessive heat caused by the medium hitting the metal is making it expand. Straight, flat panels are particularly prone to warping. One of the blasters we visited, Ron Hambright of Hambro Industries, won’t blast Chevelle or El Camino hoods because the metal’s too thin. Given the potential for damage, do some research and get referrals regarding the blasting operators in your area before bringing them your project car.
The best medium for your stripping job depends on what you expect to find beneath the top layer of paint. If you’re stripping only a couple of coats of paint and you don’t anticipate encountering much body filler or rust, or if you’re stripping a nonmetal material such as fiberglass, a soft medium such as baking soda will work fine. The trade-off: Soda won’t cut into rust. For cancerous panels or sheetmetal that’s thickly coated with filler, a more aggressive medium such as aluminum oxide or DuPont’s StarBlast will work better. Even with the more abrasive media, though, the operator has the option of removing filler entirely or just roughing it up for paint.
No matter which medium you choose, some disassembly will be required before you take your car to the blaster. If you’re painting just the exterior, the prep job is easier, as all you need to remove are the car’s trim pieces, bumpers, lights, and so on. For an “outside only” job like this, blasters can mask over glass to protect it from overspray and ricocheting media. But if you’re planning a full-on, jambs-included, inside-and-out color change, you’ll need to take off the doors, hood, and trunk lid, plus strip the interior of all upholstery, glass, carpet, and the instrument panel. Better access for the blasting nozzle gives you a more complete strip job.
It makes a difference regarding the job’s price, too. The blasters we visited didn’t have set prices for their work; the cost of the stripping depended on how much prep they had to do, how much car there was to strip, how long it took to get the metal clean, and whether the job was outside-only or inside-and-out. The more disassembly work you can do to make the blaster’s job easier, the less the job will cost.
Given all the variables listed above, the blasters we interviewed were hesitant to give exact price quotes. But here are some ballpark figures: Hambright, who uses StarBlast for most automotive sheetmetal, said an outside-only job for a typical muscle-era car would run about $500. An “inside, outside, underneath” job on a unibody car like a Mustang runs closer to $1,400, he said, “and that’s every part of the car, including suspension.” A stripped ’57 Chevy we photographed at Hambro was a $700 job, but that was because “there were no inner fenders to do, no frame or suspension pieces,” Hambright said.
Manny Vega, whose Anacapa Soda Blasting stripped Editor Rob Kinnan’s ’69 Camaro with baking soda, estimated the job at between $1,400 and $1,600. That encompassed the body’s exterior (including the fenders, cowl, and other miscellaneous parts, which were off the car) and the inside of one door, but not the rest of the interior, the firewall, or front subframe.
Both blasting shops perform a thorough cleaning of the car after blasting.
Hambro blows the StarBlast media out with compressed air and is able to reuse it. The Anacapa crew blows, vacuums, and even hoses out the used soda, which basically turns to talc on impact and can’t be used again.
Water on bare sheetmetal? Yep. Vega claims the soda dries out the panels so thoroughly that as long as there’s no standing water on the steel, it won’t oxidize for days, even weeks. (Anacapa is located in Oxnard, California, near the coast, and we saw a lot of bare metal there that hadn’t started to oxidize even after sitting for months.)
Because it’s a relatively soft medium, soda will leave the bare metal fairly smooth. Some painters may want to scuff the metal with fine paper to promote adhesion before shooting primer. A medium like StarBlast, on the other hand, leaves the surface a little rougher, so no sanding is necessary prior to priming, Hambright said. To have your car paint protected, you must choose a good car detailer, click here if you haven’t yet.
