Custom Interior Panels

Part 4 of our custom door panel articles

"Body Filler"

By now, your custom interior panels, or door panels should have some resin applied to them and are beginning to look like what you had in mind for your custom car or truck interior.  They should be fully dried, test fitted, sanded, and cleaned before proceeding to the next steps in this process.  The next few steps involve applying a body-filler, i.e. Bondo, to the "glassed" portion(s) of your door panels, then sanding it smooth to achieve a perfectly smooth finish.
Please remember that you need to wear a dust mask, protective gloves and safety goggles when working on your door panel project!

The whole idea behind using a body-filler is that it is easy to spread and fills low spots in your panel easily.  It is also far easier to sand than that of the resin you applied in the earlier steps.  Consider the resin you applied to be the skeleton of the custom door panel and the body filler is the skin.  After sanding the bondo with progressively finer sandpaper, your door panels will become extremely smooth and ready for paint.

The next step is to mix up body filler and apply it in light coats to fill the low spots in the custom interior panels resin coat.  
  • Follow the instructions on the can of body-filler to learn how much hardener to add!  Too much hardener will cause the body-filler to dry to quickly and will make it impossible to spread.  Too little hardener will make the filler take forever to dry!
  • Do small sections at a time to avoid mixing up too much or too little.
custom fiberglass door panel impala SS custom fiberglass door panel impala SS bondo
custom fiberglass door panel impala SS custom fiberglass door panel impala SS

Using your plastic spreaders apply the body filler in thin layers and sand with 150 grit paper between each layer.  Use you sanding block on the large flat areas.
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Keep applying body filler and sanding until you get the panel extremely smooth!
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(Sometimes, making a special tool can really help you out.  This 5-hour  Energy Drink bottle came in handy for sanding a curved area under my armrest after I finished getting my energy boost!)

If after sanding your last coat of body filller, you can see little pin-holes, don't go through the trouble of mixing up more body filler.  Instead, use glazing, or spot-filler putty.  It does not have to be mixed up and spreads  like hot butter and is used to fill up those little pinholes that are left behind aftyer sanding body filler.
  • Before applying the glazing putty, make sure that the panel is completely sanded and all you need to do is fill the tiny pin-holes.  
  • Take a red Sharpie Marker and go over the custom interior panels and mark circles where you need to add glazing putty.  This will make it easier to remember where the spots, or pin holes are.

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