How to Use Body Filler to Repair Dents as an Auto Body Technician

auto body technician

Body filler is a thick resin that is commonly used to repair dents, and brands such as 3M’s Bondo are often utilized for this type of repair. When done properly, body filler can make dents and other types of exterior vehicle damage look revitalized and back to its original form.

From smaller-sized dents to ones caused by hail damage, body filler can help cars look like new. Here’s how you can use body filler to fix dents during your own career as an auto body technician.

You’ll Need More Supplies than Just Body Filler to Get the Job Done

While you’ll obviously need body filler to do this kind of dent repair (whether it’s standard, medium, or premium grade filler), you’ll also need various other types of materials and tools. These include sandpaper, spot putty, plastic spreader and automotive primer, as well as a mask, gloves and safety goggles, to name a few. Repairing dents with body filler is a multi-step process—which we’ll expand on shortly—and requires attention and care, so make sure you have all the necessary equipment and accessories on hand. On top of that, repairing dents with body filler can be time-consuming, so patience is needed as well.

Many tools should be used while repairing dents with body filler, including putty
Many tools should be used while repairing dents with body filler, including putty

The Process Itself Doesn’t Start By Applying the Filler Right Away

Since body filler and paint don’t mix or stick well to one another, the auto body technician doing this kind of job has to make sure the surface itself is prepared and sanded beforehand. Removing a minimum of three inches beyond the dent, you must prepare the surface efficiently before mixing in the body filler (comprised of both base filler and hardener) before it hardens. Hardening usually takes less than five minutes. Using a plastic spreader, add filler and spread it a minimum of three inches outside of the dent, while smoothing the filler out so that it is flush with the surrounding surface. Once that part of the process is taken care of, you’ll have to start sanding again.

Any Auto Body Technician Will Need to Do a Whole Lot of Sanding

The most crucial part of the process isn’t so much filling in the damage, but sanding it out to make sure it’s done the right way. This is where the use of sandpaper obviously becomes extremely important. After the filler hardens, wrap the sandpaper around a sanding block. Sand lightly over the surface with circular strokes and sand past the filler’s edge in order to smooth out the area. After this step, switch to a sandpaper with more grit to it and keep sanding until even. Next, take spot putty and glaze it across the surface before sanding the spot putty evenly. Spray primer over the surface, and let dry before sanding over it once more. Since anyone in auto body training will be taught how to recondition and repair the exterior of vehicles, this is one type of auto body repair worth learning and mastering.

 Sanding is one of the most important parts of the process, and needs to be done repeatedly
Sanding is one of the most important parts of the process, and needs to be done repeatedly

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