Types of Body Fillers for Cars: What You Need to Know

When it comes to repairing dents and dings or restoring an older vehicle, knowing the right type of body filler to use can go a long way towards ensuring you achieve the look and repair you desire.

Body fillers are generally a polyester resin based filler with a cream hardener that can be used to even out dents and cover blemishes on vehicles. Sometimes even the term "body filler" makes auto guys cringe, but understanding the different types of body fillers and their optimal use is extremely helpful. Repairing hail damage, dents, dings, or small holes in the body of your vehicle can actually be a simple project that can be completed at home with good results.

The type of body filler you select for your restoration or repair project will depend on the scope of the project, the type of restoration, and your preference on types. Before using any putty or filler, you'll need to make sure the area you're repairing is washed and dried. Fillers won't bond well to smooth surfaces so a thorough sanding to the site is also important. Filling an area that contains rust is never recommended.

In a few cases, staining from the filler can be an issue as the chemicals in the filler interact with the makeup of the automotive paint. Using a quality primer when painting, selecting decent grade body filler, and avoiding fill work when humidity is high can help decrease chances of staining. Ensuring you add the correct amount of hardener, taking the time to thoroughly mix the filler you use, and avoiding trapped air during handling will also help.

Types of Body Fillers

Body fillers all fall into three general categories: standard, mid-range, and premium, and are generally available in a two-part material consisting of a polyester resin and a cream hardener. The filler grade you select will depend on the scope of the project and the size of the damaged spots needing to be repaired. Standard grade is a great option for minimal hail damage and small rust spots, while premium grade should be used for actual tears or a large surface area.

Standard Body Fillers
Standard grade body fillers are a lightweight substance or putty that spreads easily and cures in about 20-25 minutes. While not appropriate for use on galvanized steel, standard grade fillers are perfect for repairing minor dents and scratches. They sand easily to blend in with the rest of the vehicle once primed and painted. Standard grade also offers the least stain-resistance.

Medium Body Fillers
Medium grade body fillers adhere well to a wide variety of body surfaces since they are fiber-glass filled. Due to being a slightly higher quality than the standard grade, medium grade body fillers hold better stain-resistance. They are perfect for repairing small holes, tears and cracks in metal and fiberglass.

Premium Body Fillers
Made from top-quality resin that has the highest stain-resistance of the three, premium grade body fillers are the easiest to sand down and offer the best adhesion of filler materials to underlying surfaces. This type of body filler is best used when high-quality work is required or there are large areas or dents needing to be repaired.

Tips and Tricks For Using Auto Body Fillers

Always combine the exact amounts of filler and creme hardener as instructed on the packaging to achieve the best results. Too much hardener to filler ratio and the filler will be brittle and crack, and too little will delay drying and hardening almost indefinitely.
Use a non-cardboard mixing board when combining the filler and hardener. Because of its absorbent properties, cardboard can affect the chemistry of the filler. Auto Body Toolmart sells disposable mixing boards that are designed specifically for mixing body filler. Completing any filler projects on a warm dry day, as opposed to a humid day, will help the filler cure faster.
NEVER use filler over an area that has pre-existing rust. When rusty spots are not removed first, there is higher potential for staining and discoloration, and the filler will not adhere completely. For best results, remove the rust and then proceed. Filler adheres best to non-smooth surfaces, so sanding the area that needs improvement
to roughen the surface is essential to achieving the best results possible.
Occasionally, your filler will feel as if it's hardening too quickly during the application process. You avoid this problem by having a filler thinner on hand. Sometimes called "Honey", Evercoat's filler thinner is fiberglass-reinforced -- much like a medium grade filler -- and helps keep the filler spreading evenly and smoothly.

For all your painting and body filler needs, there's no better place to shop than Auto Body Toolmart. Browse our body fillers today.