Should I Use Putty or Bondo for Cars?

[HenryAnn]

It is recommended to use putty for cars. Putty consists of A epoxy resin and B polyamide hardener. A common hardening method is to add more hardener when kneading the putty. The chemical method involves using ethylene glycol and acetic acid, but this only theoretically accelerates the curing process of this type of AB epoxy resin. Both putty and bondo are used for repairing models, as well as for creating modifications and custom parts. Before drying, they are used to adhere to the model. Once dried, they become hard. However, bondo is toxic, so it is not recommended unless absolutely necessary. Even when used, it should only be operated in a well-ventilated area while wearing a gas mask.

[OMartin]

With over a decade of auto repair experience, I often see confusion between polyester putty (commonly called 'atomic putty') and general body filler ('bondo'). Fundamentally, both are automotive fillers. Polyester putty specifically refers to polyester resin-based compounds - it cures faster, offers higher hardness, and is better suited for deep dents or large-area damage. General body filler is more versatile, encompassing various paste-like materials, some ideal for quick touch-ups on minor scratches.

In practice, I always start by cleaning damaged areas thoroughly. For major imperfections, I prefer polyester putty because it minimizes shrinkage after drying, resists cracking, and sands effortlessly. Minor blemishes get quick-fix treatment with general filler to save time. Safety reminder: wear gloves and masks to avoid skin contact with chemicals. Apply thin, multiple layers and allow complete drying before sanding smooth - rushing compromises results. Price-wise, polyester putty costs slightly more but lasts longer. Always choose reputable brands to ensure paint compatibility and avoid substandard products affecting final finishes.

[LaSavannah]

I enjoy tinkering with my car. Last time the door got scratched, I was torn between using polyester putty or filler. After some research, I found that polyester putty (often called "bondo") is a specialized type that dries quickly and sands easily, while "filler" is a general term that might include ordinary seam sealants. For DIY repairs, polyester putty is my go-to choice because it hardens firmly and sands smooth for easy repainting. It's affordable too—just a few dozen yuan for a small can. But remember to apply thin layers to avoid bubbles and uneven surfaces. For minor scratches, soft filler is quicker and simpler, though quality matters—cheap products may crack after drying. Safety tip: Work in a ventilated area, wear protective goggles, avoid inhaling dust, and check for smoothness before painting. Regular cleaning of surface dirt can extend the putty's lifespan and reduce the need for touch-ups.

[MakaylaLee]

From a material perspective, automotive repair putty is mostly polyester-based, offering fast curing and excellent hardness; while filler putty refers to a broader category of filling compounds. Both can handle dents, but repair putty provides more stable performance, making it suitable for professional repairs. I recommend choosing repair putty due to its low shrinkage rate, high smoothness after sanding, and better painting results, whereas ordinary filler putty is prone to mold in humid environments. During application, ensure the metal surface is free of oil and dust, apply a thin and even layer, which will initially cure in about 10 minutes, then lightly sand with sandpaper. Safety should not be overlooked—wear rubber gloves to prevent irritation, keep children away from the work area, and store properly to prevent expiration.