How To Apply BONDO/Body Filler - The Right Way - Ultimate FAIL!

Applying bondo/body filler can be a real challenge when you don't know what your doing! Body Filler is not made to be applied to a painted surface. Bare Metal is the key factor to this situation.

How Do I Prepare For Bondo?
First step: Prep the Surface

Before applying, paint needs to be sanded to the bare metal. Make sure to sand outside of the repair area as Bondo will need to be spread and applied wider than the damaged area. (36-grit to 220-grit should do the trick for body filler application).

How Do You Sand Bondo?
Cut and sand

Once the Bondo cures, it's time to sand. Power sanders are OK to break the surface and knock down any high spots, but hand sanding with the body contour is the best way forward. Cut in with heavier grit sandpaper and work out to about 80 grit to leave a tooth for the following skim coats.

Should You Prime Before Body Filler / Bondo?
Do not proceed to Primer Filler stage until filled area is even. Adding body filler AFTER primer filler should be avoided to prevent possible adhesion, staining and shrinkage concerns.

Can I apply bondo to bare metal?
Before adding any filler, you should get the metal prepped and cleaned ... For small repairs, you can bog directly over the bare metal. If the repair is larger, or you're looking for a longer-lasting job, do not apply a base coat of epoxy primer before laying on the filler.