Understanding the Different Types of Auto Body Fillers


Understanding the Different Types of Auto Body Fillers

Auto body fillers are crucial materials used in car repairs to smooth out dents, scratches, and other imperfections on a vehicle’s surface. Whether you’re a professional in the auto repair industry or a DIY enthusiast, understanding the different types of auto body fillers can help you choose the right one for your needs. This article delves into the various types of auto body fillers, their uses, and how they can benefit Australians looking to maintain their vehicles.

What are Auto Body Fillers?

Auto body fillers, commonly known as Bondo, are materials used to fill dents, dings, and scratches in a vehicle’s body. These fillers are applied after the damaged area is sanded and cleaned, and they harden to create a smooth surface that can be sanded, primed, and painted.

Types of Auto Body Fillers

1. Standard Polyester Fillers

Standard polyester fillers are the most commonly used fillers in the automotive repair industry. They are easy to mix, apply, and sand, making them a popular choice for both professionals and amateurs.

  • Pros: Cost-effective, easy to use, widely available.
  • Cons: Can shrink over time, not ideal for high-stress areas.

Standard polyester fillers are versatile and can be used for a variety of repairs. They consist of a polyester resin mixed with a hardener, which when combined, creates a putty-like substance that can be easily applied to the damaged area. After hardening, the filler can be sanded down to create a smooth surface, ready for painting.

2. Lightweight Fillers

Lightweight fillers are similar to standard polyester fillers but with a lighter consistency. They are easier to spread and sand, making them ideal for larger surface areas.

  • Pros: Easy to sand, good for large areas, less prone to sagging.
  • Cons: May not be as strong as heavier fillers.

Lightweight fillers are perfect for filling larger dents and surface imperfections. They provide a smooth finish with minimal effort, reducing the labour time required for sanding and shaping. Despite being lightweight, these fillers still provide a durable and long-lasting repair.

3. Fiberglass Fillers

Fibreglass fillers are reinforced with fibreglass strands, providing added strength and durability. They are suitable for repairing larger dents and areas that require extra reinforcement.

  • Pros: High strength, durable, good for structural repairs.
  • Cons: More challenging to sand, more expensive.

Fibreglass fillers are used in areas that need extra strength, such as structural components or large dents that compromise the integrity of the vehicle’s body. The fibreglass strands within the filler increase its tensile strength, making it more resilient to stress and impact. However, this added strength comes at the cost of increased difficulty in sanding and shaping.

4. Metal Fillers

Metal fillers contain metal particles, such as aluminium, providing a stronger and more durable finish. They are ideal for repairing metal surfaces and areas exposed to high stress.

  • Pros: High durability, can withstand high temperatures, excellent adhesion to metal.
  • Cons: Harder to work with, more expensive.

Metal fillers are excellent for repairs on metal surfaces where extra strength and durability are needed. The metal particles within the filler enhance its resistance to high temperatures and physical stress, making it ideal for repairs on engine components or areas exposed to heat.

5. Glaze and Spot Putty

Glaze and spot putty are fine fillers used to fill small imperfections and pinholes. They are applied in thin layers and sanded smooth to create a flawless finish.

  • Pros: Easy to apply, excellent for minor imperfections, smooth finish.
  • Cons: Not suitable for large repairs, requires multiple layers.

Glaze and spot putty are used for the final touches in the repair process. They are perfect for filling minor imperfections, such as pinholes and small scratches, that are not covered by standard fillers. These fillers are applied in thin layers and provide a smooth finish that blends seamlessly with the surrounding surface.

How to Choose the Right Auto Body Filler

Choosing the right auto body filler depends on the type of repair, the area being repaired, and the desired finish. Here are some factors to consider:

  • Size of the Repair: For large dents, fibreglass or metal fillers are ideal. For smaller imperfections, lightweight fillers or spot putty work well.
  • Surface Material: Metal fillers are best for metal surfaces, while polyester fillers can be used on a variety of materials.
  • Durability Requirements: If the repaired area will be under stress, choose a stronger filler like fibreglass or metal.

Application Tips for Auto Body Fillers

Proper application of auto body fillers is crucial for a smooth and durable repair. Follow these steps for the best results:

  1. Prepare the Surface: Sand and clean the damaged area thoroughly.
  2. Mix the Filler: Follow the manufacturer’s instructions for mixing the filler.
  3. Apply the Filler: Spread the filler evenly over the damaged area, slightly overfilling to allow for sanding.
  4. Sand the Filler: Once the filler has hardened, sand it smooth with progressively finer grit sandpaper.
  5. Prime and Paint: Apply a primer to the repaired area, followed by paint to match the vehicle’s colour.


Understanding the different types of auto body fillers and their uses can help you make informed decisions when repairing your vehicle. Whether you’re dealing with minor scratches or larger dents, there’s a filler that can meet your needs. By choosing the right filler and applying it correctly, you can achieve a smooth, durable finish that restores your vehicle’s appearance.

Suggested Reading

  1. The Top 10 Mistakes to Avoid After a Car Accident
  2. How to Maximise Your Car’s Resale Value After Collision Repairs
  3. The Importance of Wheel Alignment After a Collision Repair
  4. Preparing Your Teen for Safe Driving in Adelaide: Collision Avoidance Tips