Why does fixing a dent in a bumper require the removal and repainting of the entire bumper?
In: Engineering
There’s a few reasons. The first, and most important is that when dealing with insutrance they have an obglation to bring the vehicle to the condition it was before the accident. That means that the resulting repair must be flawless.
If you are repairing your own bumber and are willing to accept something less than flawless than you can get it done for quite a bit cheaper.
So lets understand something. What you call a number is actually a bumper cover. It’s a large piece of plastic or fiberglass that has been painted. The actual bumper is made of metal and is under the bumper cover.
When a bumper cover is dented or damaged in any way there’s a few concerns. First is that the plastic under the paint has cracked. The plastic is not actually very flexible and tends to crack rather than just bend or dent. If you just paint over this, the vibrations from the car will cause the paint to crack over and over.
So you sand away all the old paint and can now see the cracks underneath. Depending on how large the cracks are, you may or may not be able to repair them with some kind of bonding material. If the cracks are to large, the whole bumper cover needs to be replaced. If the cracks can be repaired then it’s possible to save the bumper cover.
An insurance company will often replace a bumper cover if there’s even a hint of a crack in it. A do it yourself type job looking to save money can repair a lot of cracks that insurance companies would demand a replacement for.
So the bumper cover is now repaired or replaced and now you need to paint it. The problem is, the paint on your car has been faided in the sun form what it was at when the car was brand new. So even if you use the exact dealers paint there will be a slight paint mismatch.
In addition, auto paint is actually 2 (or more) layers of colored paint and clear coat on top. You can’t just paint colored paint on top of clear coat and expect it to look OK. So painting a small section is very hard because at the edges there will always be overlaps on the colored paint layer and the clear coat layer.
It CAN be done, but it requires some advanced painting techniques that actually take longer than just painting the whole damn bumper cover. So when being done to insurance company standard it’s actually cheaper to paint the whole panel.
In addition to this paint, you are still going to be able to notice a slight color mismatch where one panel meets another. So sometimes they do a little feathering around those edges so that the paint translation is not as stark.
But again, if you are doing a DIY job, you might settle for “good enough” and that’s a totally different standard than what an insurance company is going to do.
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