How to Choose the Right Body Filler: A Practical Guide for Perfect Repairs

Every repair project is unique. Whether you’re fixing a dent, reshaping a panel, or getting a surface ready for paint, body filler is the step that defines the quality of your finish. But with so many types available lightweight, aluminum, extra soft, plastic,  how do you know which one to use?

This guide will help you understand:

• What body filler does and why it matters.

• The different options from KMK Refinish USA.

• Which filler is best for each repair scenario.

Ideal for beginners learning the basics and professionals refining their craft, this article covers it all.

 What Is a Body Filler?

Body filler (or putty) is a two-component material (resin + hardener) used in auto refinishing to:

• Fill dents, scratches, and imperfections.

• Reshape damaged areas into their original form.

• Create a smooth, even surface before priming and painting.

Once applied, cured, and sanded, the surface is ready for primer and topcoat — giving your repair a seamless look.

KMK Refinish Body Filler Options

KMK 1901 / 1903 – Lightweight Premium Body Filler

• Sizes: 0.9L and 3L

• Key Benefits:

  • Easy spreading and sanding

  • Excellent adhesion to steel, aluminum, and fiberglass

  • Minimal shrinkage

• Best for: General repairs, reshaping panels, prepping large areas.

Why choose it?
Beginners love its creamy texture. Pros appreciate the speed and consistent results.

 KMK 1801 – Lightweight Superior Body Filler

• Size: 0.9L

• Key Benefits:

  • Ultra-smooth finish

  • Perfect for feather-edge blending

  • Designed for thin, precise layers

• Best for: Final layers before priming, eliminating small imperfections.

 Why choose it?
 Reduces the need for glaze and ensures a professional-grade finish.

 KMK 12750 – Extra Soft Putty

• Size: 750ml

• Key Benefits:

  • Extra flexibility

  • Easy sanding on curves and thin surfaces

• Best for: Light corrections and smooth transitions.

 Why choose it?
Ideal for beginners learning sanding control, yet precise enough for delicate finishing work.

KMK 1301 – Aluminium Putty

• Size: 2kg

• Key Benefits:

  • Reinforced with aluminum powder

  • Exceptional mechanical resistance

  • High tolerance to heat and vibration

• Best for: Structural repairs, commercial vehicles, or heavy-duty areas.

Why choose it?
When strength and durability are critical, this is the filler to trust.

KMK 15500 – Putty for Plastic

• Size: 500ml

• Key Benefits:

  • Flexible and elastic formulation

  • Adheres perfectly to bumpers, trims, and plastic body parts

• Best for: Restoring OEM shapes and repairing plastic panels.

Pro tip: Use together with KMK 31750 Plastic Primer for optimal adhesion.

 Pro Tips for Flawless Application

1. Surface prep first: Degrease with KMK 6005 Normal or KMK 6105 Slow Degreaser, then sand with 80–120 grit.

2. Mix correctly: Keep the resin-to-hardener ratio balanced — too much or too little can ruin the repair.

3. Thin layers win: Build it up gradually instead of applying too much at once.

4. Right tools: Flexible spreaders prevent air bubbles and unevenness.

5. Sanding technique: Start with 80 grit, finish with 180–220 for smooth blending.

 Final Thoughts

Choosing the right filler can transform a dented, damaged panel into a surface that looks as good as new. For DIY beginners, it’s a forgiving material that teaches patience and technique. For professionals, the right KMK body filler saves time, reduces rework, and guarantees long-lasting results.

At KMK Refinish USA, we provide fillers built for every challenge from quick cosmetic fixes to heavy-duty structural jobs.

✅ Ready to perfect your next repair?
👉 Explore the KMK Body Filler Collection engineered for precision, performance, and professional results.