Easy Basics of using Bondo® Body Filler

Whether restoring classics or just fixing dents on a current car, here are some simple, economical tips to help car owners do their own dent repair.

Step 1.
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.

Step 2.
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 slide hammers, hammers, mallets, dollies and picks may be needed to perform this step. Always use appropriate eye and respiratory protection.

Step 3.
After the dent is roughly removed it is time to start sanding. Use a sanding block or random orbital sander with a 80 grit abrasive sheet to remove all paint to approximately 2" around the dent.

Step 4.
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.

Step 5.
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.

Step 6.
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.

Step 7.
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.

Step 8.
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.

Step 9.
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.

Step 10.
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.

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