"Hey, nice ride!" We all love the ego stroke of unmasked admiration, and nothing dishes up an automotive narcissistic feed like nice body and paint work. A straight and gleaming muscle machine is just a magnet for praise, catching admiration for no reason but pure looks alone. It's just curb appeal. Though a highly evolved automotive taste can covet the same car, bruised, rusted, and primered, the general masses will judge on the visual, and probably the visual alone. Unfortunately, the notion of good body and paint ranks as one of the most expensive and time consuming of automotive goals. Frankly, there're only two paths by which to get there-one is to find a suitable shop, drop the car, and open the wallet wide. The alternative is to learn, understand the processes, do what you can yourself, and open your wallet not quite so wide.
For the former approach, you really don't need our help. We can give you all the advice you need in one line-find a shop you can afford that can do the job, and pick it up when it's done. If you wish to delve a little deeper, here is what's involved, from start to beautiful finish. You may not be able to produce a show-winner the first time you put these techniques to practice, but you will definitely know more about what needs to be done, and that knowledge is what it takes to trade some work for big savings down the line.
Most of us center our automotive interests on machines built decades ago, and time exposes the body to all sorts of unrighteous indignation. Now, not all paint projects necessarily require a full strip-down to bare metal. For a street driver still bearing a single decent layer of factory paint, a good scuffing of the original paint can serve as the basis for a quality re-paint. Multiple blow-over paintjobs, hacked bodywork, or dime-store primers hiding who-knows-what ills generally point to the need for a full bare-metal strip-down. There are a variety of techniques to strip the offending buildup to the metal below, and the decision on which process to use depends on the situation. Below we have a guide to the basic techniques, and where they best apply.
Blasting can be a very effective...
Blasting can be a very effective form of paint removal, readily taking difficult-to-access areas down to clean bare metal. There are a variety of blasting media, each with pros and cons, but the specialized equipment means this is almost always a commercial technique.
Blasting will quickly remove paint, and depending upon the media, will also remove rust, leaving clean, bare metal. Generally, blasting is a commercial service, and we prefer companies that specialize in automotive work. The advantage of blasting is that it will clean complex and hard to get areas, such as the contours of an engine bay, or around chassis parts, frames and components that would be very time consuming and difficult to strip by other means. The downside is that the media will get into everything that isn't protected, which can create difficulties if the vehicle is still largely assembled. Also, some components, such as glass and moldings, can be damaged by certain blast media, so they need to be protected or removed. Overzealous blasting with high pressure and heavy media can also distort body panels.
Blasting can be done with sand, which is very aggressive, and will remove all rust. Sand can cause damage if incorrectly applied or allowed into unprotected components. Other media include walnut shells, soda blasting, and plastic media, which are less aggressive and primarily remove paint with little effect on rust. We like blasting on heavily disassembled cars, particularly in hard-to-strip areas like engine bays, trunks, floorpans, and chassis members.
Sanding can knock the exterior...
Sanding can knock the exterior of an entire car down to bare metal with one day's work. Orbital sanders, such as an air-operated D/A (dual-action) sander are preferred for automotive work, since such equipment minimizes trauma on the metal below.
Sanding is one of the most straightforward techniques for stripping paint. Generally, the equipment used is air-powered, and a hearty compressor is a must to be effective. Electrical tools can be substituted here if a suitable air supply is not available. The key distinction in sanding equipment is the tool motion. Simple rotary sanders will tend to gouge the metal, though the cutting action will be quite fast. Orbital action, as employed by a standard autobody dual-action (or D/A for short) sander, will eliminate the tendency to gouge or damage the metal, though the paint removal rate is slower. Sanding is most effective at removing paint from large flat areas of the car body. We favor sanding to strip the exterior sheetmetal surfaces.
The key tip here is to use high-quality abrasive discs from a manufacturer like 3M or Norton, since the cutting is much faster, and the discs last much longer. Don't be too conservative on the grit if going down to bare metal-we wouldn't hesitate to knock back deep multiple layers of paint with #40- or #60-grit D/A discs. Although it may seem like a big job, the entire exterior of a typical car can easily be sanded to the bare metal in a day. Related to sanding are some of the many abrasive fiber discs on the market, such as 3M's Clean & Strip wheels. These come in a variety of configurations and sizes, and are ideal for quick paint removal in some of the more confined areas where access to the large D/A disc is limited.
There is a multitude of chemical stripping processes available to automotive enthusiasts. Generally, the products for home application are either brushed or sprayed on, and after some working time, the paint is scraped off. We have had very limited success with most over-the-counter products on fully cured automotive paints, especially the tough OEM paints and primers on our older cars. This is especially true since most of the highly effective but toxic methyl chloride has been removed from most of these products. We have seen some demonstrations of specialty stripping products that seem effective, but the best bet is to try a sample of the product on the material being stripped. The downside to this type of chemical stripping is that the process is necessarily messy, and time should be taken to seal off various body seams from ingress of the stripper. We occasionally use chemical strippers, but generally favor mechanical means of paint removal.
Another variation of chemical stripping is full immersion. This is a commercial stripping process where part or even the whole car body is dropped into a tank, or a series of solutions until the result is clean, bare metal. These systems can be extremely effective, especially in a total restoration scenario. We have had full car bodies subjected to the tank, and found the results very impressive. Some of these services also finish with a protective coating. For this type of stripping, total disassembly of the vehicle or component is a prerequisite.
Metal working requires a variety...
Metal working requires a variety of specialized, if somewhat crude, tools. Hammers, dollies, prybars, and slappers are all part of the rotation. In skilled hands, these can work wonders.
Virtually any paint project is going to involve some level of bodywork. If the metal is beat up, you'd be amazed by what can be fixed by hammer and dolly work. For the novice bodyman, it may seem kind of hard to believe just what can be fixed by the masters of the trade with practiced hands and eyes, and using the crudest appearing hand tools. The kind of feel for what it takes requires practice and experience, and there's only one way to gain that-by doing. Skill in metalwork may vary, and the difference in ability will just boil down to how close it will end up before slinging on the mud. It pays to have the metal as near perfect as possible.
The most basic metal working tools are body hammers and dollies. Body hammers, unlike framing claw hammers, are balanced and shaped for working sheetmetal. A good assortment is nice to have. The pointed pick end of the pick hammer is handy for precisely concentrated blows on small dings, while the light overall weight makes the flat side nice for controlled hammer and dolly work. A flat chiseled-end hammer is good for working bodylines, and the overall hammer weight is higher than a pick hammer, for slightly more forceful blows. A combination hammer is the heaviest, and has a square and a round head for working flats or corners.
A handy device for moving...
A handy device for moving metal is the stud-welder. The device welds studs to the panel surface, which are grabbed by a slide hammer puller to raise a dented area or crease. Avoid the old-school drill-and-screw dent pullers at all costs.
A dolly is used on the opposite side of the metal being hammered. It focuses the force of the hammer blow to the area being worked. Without a dolly the metal will just spring over a wide area and not move, or move in too broad of an area. Dollies come in a wide range of shapes, and can even be homemade. There are two main ways to use a hammer and dolly: hammering on the dolly, or off. In on-the-dolly hammering, the dolly is directly centered behind the metal being struck by the hammer. This is the technique for planishing (smoothing small distortions), or knocking down a bump from the outside. In the off-the-dolly technique, the dolly isn't place directly below the hammer strikes, but typically just adjacent. In this technique, the dolly is aligned to exert outward force at a low area, while an adjacent raised area or ridge is worked down. This is useful when working out larger distortions in the panel's shape.
One key thing to always bear in mind is that there's a fixed amount of metal surface, and metal always has to go somewhere if you're trying to move it around. If it goes down in one area, it will move up somewhere else.
Various bars and levers are also useful, particularly in blind areas between panels where there is no room for a hammer. Bars can vary from hardware store crowbars, or tools that are homemade and fashioned to a particular shape for the task at hand. Using a bar behind a depressed dent and applying a leverage force will often not move a dent or crease out, but holding tension against the dent while lightly hammering the adjacent metal (off the bar) will coax the metal back out to shape.