How to Spread Auto Body Filler
For the inexperienced auto body repairman, the first inspection of a rather dinged and dented vehicle may be a bit intimidating. Usually, this kind of repair work will involve spreading auto body filler. This is not quite as difficult a repair job as one may think. With some simple, basic tips and guidelines, a few tools and materials readily available at an auto parts store, and a good eye and feel for a smoothly finished surface, the job can be accomplished and turn out looking quite professional.
Tools needed
The simple tools needed for this kind of work are a hammer and scratch-awl, and a good pry bar or a screw driver made of case-hardened steel that will not bend under pressure. Files come in different grades, such as coarse, medium, and fine and are used throughout the process. A coarse file will be needed to remove any paint from the metal surface, or an orbital sander may be quicker and easier, and medium to fine files will be used for smoothing and finishing purposes. The sanding system may include a flat board, perhaps 3" wide by 18" long, used for sanding, blending, feathering, and finishing. Some plastic material spreaders will be needed for applying the auto body filler.
Preparing the metal for the filler
Using a dent about the size of a baseball as an example (although larger areas will require much more time, labor, and filler material,) try with the tools above to "pick up" some of the dent, or "bring out" the dented area without getting it too high above the surface. Use the hammer and scratch-awl for this part of the job. The coarse file or orbital sander will determine how much body filler will be needed after grinding off all the paint and any high metal.
Mixing and applying the filler
One of the most important considerations here is that there is a need to work quickly - there is no time to waste when using auto body filler. Repairers will be using one quart of body filler and one tube of cream hardener after the dent has been brought up almost level with the rest of the metal surface. The damaged area, after the preparation mentioned above, should now be bare metal, shiny, and clean. Now that same area needs to be slightly "roughed up" with coarse sandpaper in order to allow the plastic body filler to adhere to the metal. Temperature of the air in the work area and of the metal surface itself will make a difference in how much filler will be mixed at one time, because the warmer the temperatures, the faster the filler "sets up," or hardens. This will limit the window of time for working with the filler.
Using a piece of cardboard approximately 6" X 6" and a stirrer that is sturdy, put a small amount of filler not quite the size of a golf ball, on the cardboard. Flatten it with the spreader. Squeeze about half an inch of the cream hardener from its tube onto the filler. Stir the hardener into the filler until the mixture is uniform in color, and do this very quickly. Working from top to bottom, use the spreader and apply a small amount of the mixture evenly over the area to be repaired. Use another small amount to apply just below that, overlapping the mixture, using smooth and even pressure. Now the dent should be entirely filled.
Timing and final finishing
Wait approximately 10 to 15 minutes for the filler to completely harden. Level out excess filler with the coarse file until the surface is fairly smooth. Then using the sanding board, smooth the area and inspect visually and by touch for any low spots. If there are any noticeable low spots in the filled area, repeat the process with a lesser amount of filler, freshly mixed. Any remaining filler from the first batch will no longer be usable. Sand the area with the medium sandpaper, and finish up with the fine grit sandpaper to achieve a smooth, level auto body repair.
Tips on safety
When using auto body filler, be forewarned that the fumes encountered can be hazardous. A nose and mouth mask can be worn to reduce the fumes breathed in, safety glasses will protect the eyes from specks of metal or filler, and gloves will keep the hands from making direct contact with the materials. If possible, work in a well-ventilated area so that the auto body work will be a safe experience, as well as a successful one.
