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How to: Use Polyester Body Filler

No one wants to see pin holes, sand scratches, and low spots in their auto paint finish. A good Polyester body filler should be a ultra-smooth paste that makes it easy to remove these imperfections.

Here’s how to prepare the surface of your vehicle to apply polyester body filler, mix and apply the putty, and sand the car paint surface for priming:

Prepare the surface

  • Clean and degrease the entire panel you are repairing with soap and water, followed by a mild cleaning solvent such as the GLM-900 Wax & Grease Remover.
  • Thoroughly dry the surface.
  • Scuff the paint and featheredge, using 80-180 grit sandpaper.

Mix the polyester glazing putty

  • The GLM-250 Gold Fast Sanding Body Filler is a good ultra-smooth polyester body filler used for pin holes, sand scratches and low spots. Mix the putty in the can, stirring well with a metal stick.
  • Remove and place a small amount of the putty onto a clean, non-fibrous surface. A glass pane works well.
  • Prepare your tube of hardener by kneading it and squeezing the air out.
  • Add a ribbon of hardener from edge to edge across the center of a 4” (10 cm) diameter puddle of putty. Puddles larger than 4” in diameter will require additional hardener. The standard hardener ratio is approximately two to four percent. 
  • Mix the putty and hardener thoroughly with a spreader until you achieve a uniform color. Be careful not to do this for more than one minute, or the substance will cure.

Apply the mixed putty

  • Spread a thin layer of the mixed putty over the panel surface, using firm pressure.
  • Apply additional layers to build the putty layer slightly higher than the vehicle surface so it can be sanded.

NOTE: Do not apply too heavy a layer of putty over new or uncured coatings.

Allow 15 to 30 minutes for curing before sanding.


  • Block sand to contour with 180-grit sandpaper.
  • Final sand with 180-grit followed by 220-320 grit if desired.
  • Wipe down the surface with GLM-800 Pre-Paint Cleaner and a clean cloth.

Repeat steps two to four until all low spots are removed, and the surface is smooth to touch. You are now ready to apply your primer.

Now that you know how to use body filler to eliminate pinholes, sand  scratches  and fill in low spots, you can have a perfect vehicle surface without flaws.