How To Clean Bondo Before Painting

When you’re working on a car restoration project, there are going to be some repairs that are more extensive than others. In order to get the surface of your car looking as good as new, you’re going to need to take it down to its bare bones and give it an extensive makeover from the ground up.

Many auto repair projects are going to involve filling in damaged or sunken areas with an auto body filler called Bondo. This is an epoxy resin based putty that can be used for everything from small dings and chips to larger areas of damage. Once you finish repairing the surface with Bondo, however, you’re not quite finished yet! You’ll also need to clean the surface before priming and painting it. Here is some helpful advice on how to clean bondo before painting.

Choosing Your Bondo Cleaning Method

When you’re cleaning Bondo that is applied to a car’s exterior, you want to be extra careful not to damage sensitive paint jobs. A rotary buffer with a fine grit disc is going to be too aggressive for painted surfaces. If you are repairing damage on a vehicle’s interior, then a rotary buffer with a coarse disc is sufficient. A cordless drill fitted with coarse sandpaper is an extremely popular way to clean Bondo that is applied to an interior surface. Since the sandpaper is attached to the motor of the drill, you have full control over the strength and speed at which you clean the Bondo. This makes it very easy to control how aggressive the cleaning process is. If you have a particularly dirty Bondo surface that is applied to an exterior panel, you’ll want to use a chemical cleaner to remove the excess epoxy. This is a bit more time consuming than using a rotary buffer or a cordless drill with coarse sandpaper, but it’s certainly worth it if you want to ensure the Bondo is absolutely clean before you paint.

Cleaning Bondo Before Painting

Rotary Buffer with Coarse Disc

A rotary buffer with a coarse disc is going to work best for cleaning Bondo that is applied to the interior of a car. You can adjust the disc’s grit to any level you want to ensure you’re not damaging sensitive surfaces. If you want to clean both the top and bottom of the interior panels, a rotary buffer will be the more convenient option. If you only want to clean a specific area, a cordless drill with coarse sandpaper can also be used. It’s important to clean the entire surface of the Bondo so that it’s smooth and ready for paint. Otherwise, you could have paint peeling issues in the future.

Cordless Drill and Coarse Sandpaper

A cordless drill with coarse sandpaper is a very effective way to clean Bondo that is applied to an exterior panel. You can use the sandpaper to clean both the top and bottom of a panel. A rotary buffer with a coarse disc can also be used to clean exterior Bondo. You can adjust the speed of the buffer so that it’s not too aggressive. You just want to be sure to keep the disc away from the edges of the panel so that you don’t accidentally damage the paint.

Chemical Cleaners

If you have a particularly dirty Bondo surface, a chemical cleaner is the best way to get it ready for paint. You’ll just need to apply the cleaner to the surface, allow it to sit for the specified amount of time, and then rinse the surface with water. It’s a bit more time consuming than using a rotary buffer or cordless drill with coarse sandpaper, but it’s a very effective option if you have a lot of Bondo to clean. Make sure that you read the instructions on the cleaning product before you begin. Different cleaners have different directions for application and drying times.

Conclusion

No matter what type of bondo you use, you’ll want to make sure you clean off all of the excess epoxy before you prime and paint the surface. This way, you won’t have excess Bondo seep into the pores of the fresh paint job. This can be done in a few different ways. A rotary buffer with a coarse disc is a very effective method that can be used to clean both interior and exterior panels. A cordless drill with coarse sandpaper is also an excellent choice. This can be used to clean both the top and bottom of a panel. You can always use a chemical cleaner to make sure your Bondo is absolutely clean before you paint.

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