How to Fix Dents with Bondo

A rogue rock flung from a tire, an out of control shopping cart, your kid learning how not to park the hard way—there are endless ways to dent a car. And body work can get expensive fast. Luckily, plastic body fillers like Bondo make fixing dents easy. Body fillers have gotten a bad rep in some parts, but that’s due to poor use. The truth is that pretty much any high-end custom car or restoration project has some body filler. That’s because when Bondo is used right, it can fill dents and make a car look good as new.

Follow this guide to learn how to fix dents and make it look like they were never there using Bondo, the fast and easy do-it-yourself solution. We’ll show you the sandpaper and tools needed to use body filler the right way.

How to Remove Dents from Your Car

1

Clean the Car and Remove any Residue

Clean the vehicle with soap and water, followed by a residue remover. 3M Adhesive Remover is a great product for this step. This is important as any contaminants (wax, bug residue, tar, dirt) remaining when sanding begins are ground into the surface and could compromise the adhesion of repair materials.

Person sanding the paint off of a dented area on a car
2

Remove Paint from the Dented Area by Sanding

Use a sanding block or random orbital sander with an 80 grit abrasive sheet to remove all paint to approximately 2" around the dent.

Person using a dent puller to remove a dent
3

Start Working on the Dent with a Hammer, Mallet, or Dent Puller

When repairing any dent it is best to remove as much of the dent as possible prior to filling with body filler. An assortment of hammers and mallets, dollies, picks, slide hammers and dent pullers may be needed to perform this step. Always use appropriate eye and respiratory protection.

Person applying Bondo to a dented area on a red car
4

Mix Bondo and Put Down the First Layer of Body Filler

Using proper techniques mix Bondo® Body Filler using the Bondo® Plastic Spreader from 3M and apply mixed filler to the dent. The first layer should be applied with firm pressure to ensure good adhesion. Avoid over-application of filler as this just requires additional sanding. Let dry for 15 to 20 minutes, depending on temperature and humidity.

5

Shape the Filler with a Sanding Block

Select a sanding block that is appropriate for the size of the repair and attach an 80 grit abrasive sheet. Rough shape/sand the repair area. ALWAYS keep your block flat to the surface. Avoid over-sanding with 80 grit or the finished repair area will be low. If low spots are detected, it may be necessary to apply more body filler and repeat this sanding step.

6

Smooth Out the Filler with a 180 Grit Abrasive Sheet

Once satisfied with the rough shape of the repair, attach a 180 grit abrasive sheet to the sanding block and final shape the repair. After this step, the repair should be level and there should be no 80 grit scratches remaining. The body filler should also have a smooth featheredge all around the repair.

7

Use the Sanding Block to Remove Paint and Scratches

Attach a 180 grit abrasive sheet to the sanding block to featheredge the paint away from the body filler and remove all straight line scratches.

Person applying glaze to a dent that has been smoother over with body filler
8

Mix and Apply Glazing and Spot Putty

Mix Bondo® Professional Glazing and Spot Putty from 3M and apply to the entire repair area overlapping the body filler and paint featheredge. Allow 15 minutes to dry, depending on the temperature and humidity.

9

Sand the Repair Area until Level

Apply a 180 grit abrasive sheet to the sanding block and sand the repair area until level. Remember to keep the block flat to the surface at all times and do not oversand.

10

Remove Scratches from the Paint Around the Filler Area

Apply a 320 grit abrasive sheet to your sanding block and remove all straight line scratches from the paint around the filler area.

Once complete the repair is ready for the application of primer surfacer and topcoats. It’s very important to follow the paint manufacturer’s instructions for your specific brand of primer or paint.

Advice, how-to guides, and car care information featured on AutoZone.com and AutoZone Advice & How-To’s are presented as helpful resources for general maintenance and automotive repairs from a general perspective only and should be used at your own risk. Information is accurate and true to the best of AutoZone’s knowledge, however, there may be omissions, errors or mistakes.

Be sure to consult your owner’s manual, a repair guide, an AutoZoner at a store near you, or a licensed, professional mechanic for vehicle-specific repair information. Refer to the service manual for specific diagnostic, repair and tool information for your particular vehicle. Always chock your wheels prior to lifting a vehicle. Always disconnect the negative battery cable before servicing an electrical application on the vehicle to protect its electrical circuits in the event that a wire is accidentally pierced or grounded. Use caution when working with automotive batteries. Sulfuric acid is caustic and can burn clothing and skin or cause blindness. Always wear gloves and safety glasses and other personal protection equipment, and work in a well-ventilated area. Should electrolyte get on your body or clothing, neutralize it immediately with a solution of baking soda and water. Do not wear ties or loose clothing when working on your vehicle.

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