How Automotive Body Work is Really Done

Doing body work on a classic hot rod or even a new vehicle can be very challenging, especially if you're having to cover up a large area with body work. In this article I will provide some helpful body work tips that allow expert body men to get laser straight panels; and another aspect of bodywork less mentioned is the integrity of it needed to remain solid for years to come.

1) Before you start just pulling a dent and doing body work there are a few things to know and a few tools you will need. Gone are the days of the screw in the end of a slide hammer, for a novice this can be more troublesome when doing body work than is necessary. What you're going to need to pull any sizeable dent or body work damage is a stud welder, stud puller, body hammer, and a metal grinder.

2) The first thing that you are going to want to do is prepare the surface for doing body work, this can be done by stripping down the paint to mare metal with 40 grit sticky back sandpaper on a 8 inch stripping disc (like the one that would be used on a Dewalt stripper/ polisher). Once you have bare metal in the complete area of body work on the caved in damage and a few inches (two to three) of the perimeter you're ready to feather out the coarse grit scratches that bridge the existing paint to the metal, this will be done with a 6 inch palm sander utilizing 120 or 180 grit sticky back paper. Make sure to keep that palm sander flat against the metal so as not to create waves that will be visible after primer over your body work.

3) Now you're ready to spread mud or body filler as most folks call it. Right off the bat if you're trying to do body work with Bondo brand filler (the pink stuff) you've already made your first mistake (body men don't even use that stuff- too hard to work with and way too hard to sand and full of pinholes). Instead go to your local auto body paint supply house in search of the right filler for the body work you'll be doing. Evercoat fillers are the best on the market and I suggest spending a little extra doe and getting the Rage Evercoat filler; it's self leveling and pretty much pinhole free, but a little expensive at about $40 a gallon. Rage Evercoat is what professional body men use on body work because it goes on really smooth and is easy sand. Don't forget to buy a few good plastic spreaders in varying widths, these you'll need in a moment.

4) Now you're ready to pull the dent; plug in your stud welder (which can normally be had for $150-200) and load it with a shank. What you're going to want to do is weld the shanks in the deepest creased sections of your body work and you will want to weld quite a few of them depending on the size of the damage. Now to operate the stud welder all you will have to do is load it with one of the shanks (they vary in size for heavy to light metals) and push the stud welder against the surface metal and make contact while pulling the trigger, wait until the end of the shank begins to glow cherry red on your body work and sinks into the metal a few millimeters (you'll feel it); once you have done this pull the welder back to reveal that your shank is welded to the panel. Repeat this operation until you think you have all areas of body work covered for pulling the metal back to its regular shape.

5) Use your slide hammer to carefully pull the metal close to its original shape, if you pull too much on your body work remember you have a body hammer to tap it back in. When you think you have the shank pulled enough simply wiggle it up and down and it will release.

6) Use a grinder to remove any of the excess welding slag that may protrude past the level of the body filler when applied; now your body work is ready for filler. Make sure that you use a paint stirring stick to stir your filler and blend the different resins and materials that it contains. You can use a piece of cardboard to mix the filler and activator. The rule of thumb when activating filler is that after you have made a puddle of it on your mixing board (which should somewhat resemble a circle), squirt a line of the blue activator that is only the radius of that circle (in other words- half a line of the whole circle). Now you're gonna work fast at this point because one of the chief complaints I hear from novicesdoing body work is that the filler dries up to quickly and they end up smearing it on dry. The whole point of using filler is to mix it up fast with your spreader and smear it on wet.

Once you have wiped your filler on the panel (I also suggest wiping on more than you think you need as it does shrink) wait for it to start to heat up and grab some 40 grit paper and a sanding block (preferably a Durablock-they come in different lengths and are found at the autobody store) try and cut down the filler to a manageable level, very close to the surface of the metal but not all the way. Now you need to wait until the filler has hardened all the way ( about 20 minutes) and continue to block the body work down until it's flat with the surface metal. If you still have an indention from the damage don't feel bad, this is typical; you may have to wipe the panel again, maybe even three or four times. Repeat the process until you have roughed in your body work and it is flat. Now the most important thing to remember when sanding body work is that you will sand in two diagonal motions only, never up and down and left to right. Basically you make an X shape with every pass, a few strokes one way diagonally and then a few the other way.

7) Now you are going to change your sanding block paper to 80 grit and eliminate your very rough 40 grit scratches in your body work, blocking the same way described earlier. After you have successfully done that now it's time to whip out your palm sander and go over the whole thing with 120 or 180 grit, remembering to keep the sander flat against the body work.

8) We're ready to prime, obviously you are going to want to use something like 400 grit sand paper to rough up the surrounding paint before you prime your body work. When you still have bare metal exposed you will want to use a spray can of metal etching primer which is green and can be found at auto parts stores. Simply mist it over the panel, we don't want to much before the actual priming of the body work.

9) The primer that you will want to use for your body work will either be a two or three part primer with the primer and an activator and sometimes a reducer. Make sure to mix it up per the instructions and if you have questions about it ask your autobody store. You will also need a paint gun with a sizeable tip, ideally you want a 1.8mm tip.

10) Apply three heavy coats of your primer while waiting 15 minute flash times in between and finish off your primer work with a light dust coat of black spray paint for use as a guide coat and you're ready to sand it down in about 4 hours when it dries with 400 grit sand paper.