Bondo can last for years when used as a filler. However, certain factors dictate how long Bondo lasts on your car’s body. We will get much deeper into that later on.
If applied correctly, Bondo can last for more than five years. In most cases, Bondo filler lasts for two to three years.
There are car owners who have had Bondo hold on to their vehicle’s bodies for even eight years. If you want it to last that long, then you need to apply it correctly and thoroughly follow the manufacturer’s instructions.
What Factors Determine How Long Bondo Lasts?
As mentioned above, certain factors determine how long Bondo lasts. Familiarizing yourself with these tips is crucial because you will be able to avoid the little mistakes car owners make when using this product.
1. The Mixture Ratio
It is quite common for Bondo to crack and fall off a few weeks after application. Most people end up blaming the manufacturer, 3M, for this.
Others think the cause of this is that the product is inferior. Most car owners don’t know that the mixture ratio is the leading cause of Bondo’s short lifespan on your car’s body.
For Bondo to stick and hold as a filler, it should be mixed with a hardener. The recommended ratio is mixing an inch of hardener with a golf ball-sized Bondo.
This ratio will ensure the Bondo mixes in the right proportions, thus ensuring it lasts for as long as possible.
Bondo can last for more than five years if you get the ratio right. However, if you use too much hardener or too little, the Bondo will crack in a year or two.
When that happens, the likelihood of it falling off is very high. Upon purchase of this body filler, go through the packaging and confirm with the manufacturer’s instructions. There should be some information on what the correct mixture ratio is.
2. The Presence of Rust
Folks living along the salt belt experience a shorter Bondo lifespan than those in other parts. You may be wondering what rust has to do with Bondo’s lifespan.
When rust forms around the Bondo, it detaches the metal from the filler. The Bondo is left with nothing to hold on to, and that’s why it falls off.
Rust can significantly reduce the lifespan of Bondo. That’s why you must take all necessary measures to ensure you keep rust from reaching the metal.
After applying Bondo and spraying paint on top of it, you may think that you have kept rust away.
However, one of Bondo’s ingredients may go against your back and invite moisture in. Talc, a key ingredient found in Bondo, attracts moisture and holds onto it.
This creates a recipe for rust on the inside.
Because this is unavoidable as long as you use Bondo, we advise you to opt for fiberglass fillers. These do not contain talc. Therefore they do not attract moisture which leads to rust and shortens the lifespan of the filler.
Fiberglass fillers aren’t as easy to apply as is the case with Bondo. But, they last fairly long because they don’t attract moisture.
3. The Thickness of the Bondo
Bondo should never be applied when it’s too thick. The recommended amount of dent or scratch that should be filled with Bondo should be at least a quarter inch deep.
With Bondo, there is no limit on how thick it should be. You can even apply it to a dent that is 3 inches deep. However, the thicker the Bondo, the shorter it will last.
When it’s too thick, the Bondo starts to shrink after a while. When that happens, it becomes loose and starts to fall off. However, a slightly thin Bondo doesn’t shrink as fast. It will thus serve you for longer.
Is Bondo Permanent?
According to the manufacturer, Bondo cures into a permanent material. However, being permanent is one thing, and lasting for longer is another.
Bondo filler will cure and harden onto the scratches and dents, creating a very smooth finish upon application. However, after a while, it will either shrink, crack, or start to peel off on its own due to the above factors.
We can’t say that Bondo is permanent. We can agree that it does last for a while when mixed in the correct ratio.
Does Surface Preparation Affect Bondo’s Lifespan?
Yes, it does! How long Bondo lasts depends on the nature of the surface it has been applied. Suppose you apply the filler on a dirty and contaminated surface.
The contaminants will prevent the Bondo from adhering to the walls of the metal. Secondly, if the surface isn’t Bondo-friendly, it won’t stick.
When applying Bondo on a car, it is recommended that you do it correctly. The first step usually entails surface preparation.
This can range from activities such as cleaning the part where the Bondo will be applied. Sand the surface to remove the paint.
Bondo works best when applied on bare metal. The other thing that can be involved in the Bondo application is the removal of rust.
We have already seen that rust itself lowers the lifespan of Bondo. Before applying it, you should remove rust. Failure to do so can cause the rust to spread to other parts, which is quite dangerous.
Will Bondo Fall Off If I Hit a Bump?
This depends on where the Bondo is applied to and how hard you hit the bump. Another factor that comes into play is how well you applied Bondo.
If you did a shady job, the Bondo would come off instantly when you hit a severe bump. The force that comes from hitting a severe bump shouldn’t be strong enough to remove a properly installed Bondo.
Bondo sticks excellently well to bare metal. You shouldn’t be worried about it falling off if you apply it correctly.
However, if you have Bondo-ed the bumper, it can come off when driving on an uneven road.
Will Bondo Last Long If Used to Fill Holes?
Not at all! Remember, Bondo is meant to smoothen out uneven surfaces. It is not formulated to fill holes. When you use it to fill deep holes, it will crack and eventually fall out.
When placed in a hole, Bondo shrinks after some time. If you have dents in the form of holes, we would recommend other repair measures and not Bondo. How long will it last when used to fill holes?
If you want to use Bondo as a short-term solution, give it a couple of months before it starts to show signs of wear when used to fill holes.
How Long Till Bondo Cracks?
On the internet, there are several bad stories about Bondo. A lot of car owners expect Bondo to crack eventually. Even though it isn’t a permanent solution, Bondo will not crack if mixed and applied correctly.
Bondo will crack after a couple of months if the surface being applied to isn’t scratched to promote adhesion and is free of dirt and rust.
Another thing that may contribute to these cracks is using an incorrect amount of hardener. Always pay attention to the instructions provided by the manufacturer.
Can Bondo Outlast a Car?
If you have only had terrible experiences with Bondo, it can be hard for you to believe that Bondo can outlast a car. The truth of the matter is that many car owners applied Bondo, and it outlived the vehicle itself.
In the car industry, provided you know how to get the most out of a product, it should serve you for a long time. Bondo is a renowned body filler that is made using quality ingredients. It is meant to last for long.
The problem with most DIY enthusiasts is that they don’t mix it correctly or follow the required application techniques. This results in Bondo lasting for a significantly shorter duration.
You shouldn’t be surprised to see Bondo outlasting a car. What you should be worried about is why the Bondo you keep on using doesn’t go for months without cracking or falling off.
Bondo-Glass vs. Ordinary Bondo Filler – Which One Lasts Longer?
Bondo-glass, as mentioned earlier, requires a lot of work during application. However, it lasts longer than an ordinary body filler. The talc in ordinary Bondo attracts moisture which leads to rust.
Bondo-glass, on the other hand, doesn’t do this. That’s why it’s such an excellent choice for people who are tired of Bondo falling off due to rust.
Does Bondo Fall Off Eventually?
Because it’s not a permanent product, Bondo will fall off eventually, even if it’s after ten years. In the meantime, Bondo should stick on your car.
How Durable is Bondo?
Bondo is a durable filler that can last for a long time when applied correctly. It is very durable and offers great results in improving your car’s finish.
In terms of improving the car’s finish, Bondo isn’t very durable because it discolors faster when exposed to UV rays. You may have to paint it time after time.