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Why Does Bird Dirt Wreck Paint?

Why Does Bird Dirt Wreck Paint?

We all know that the runny white stuff is bad for our car’s paint, but why? What do bird droppings do to our paint?

After spending a beautiful summer’s afternoon giving your car a well deserved wash, it feels great to stand back and admire a job well done. What doesn’t feel so good is spying that flock of birds on the telephone wire or up in the tree near your vehicle waiting to do what they do best.

Whatever you call it – bird droppings, bird poo, guano, or anything else – this substance that car owners are too familiar with is unsightly and does significant damage to your vehicle. In this article, we are going to break down exactly what bird dirt does to your clear coat, and what you can do to prevent it.

Get ready for more information than you’ve probably ever wanted to know about bird poo – but don’t worry, there is a point. Bird excrement contains high proportions of Uric Acid, a corrosive chemical that can damage wax clear coat, and paint.

The Chemistry

Acidic and alkaline substances are measured on a scale from 0-14, known as the pH scale. Acids range from 0-7, and bases range from 7-14. The uric acid present in bird droppings gives the entire substance a typical pH between 3 and 4.5, which is considered quite acidic.

Specifically, pH measures the levels of hydrogen and hydroxide ions (H+ and OH-, respectively) in a solution. A substance is considered acidic when the hydrogen ions outnumber the hydroxide ions. All acids and bases want to get themselves to a neutral pH, and they do this by “stealing” ions from any substance they come in contact with.

That means that the uric acid contained in bird droppings will react with the hydrocarbons of your car’s finish, as the acidic solution tried to steal away the OH- ions. Over time, this process will break down the clear coat.

The Physics

If we can remember back to high school physics class, we might recall the principles of thermal expansion. This principle applies to substances changing size due in response to the application or removal of heat. The hotter a substance gets, the more violently the molecules bounce around. When molecules are bouncing around with a lot of energy (because they are hot) a substance will grow slightly.

If you’ve ever opened a stuck jar by running the lid under hot water, you have observed thermal expansion at work; the heat made the lid grow slightly, and therefore be easier to unscrew.

When the sun warms your car, the paint and clear coat undergo thermal expansion. When the clear coat expands, it become slightly porous, and allows uric acid from bird droppings to seep in. When the paint cools down at night, the uric acid is trapped inside the clear coat where it can engage its corrosive tendencies. Over time, the uric acid will be able to penetrate all the way through the clear coat and into the pigmented paint underneath.
Repeated processes of heating and cooling result in physically deformed paint which appears etched and dull.

What Can You Do?

In this case, prevention is obviously the best protection possible. You can try to park out of range of passing birds, or invest in car covers and paint protection films. But sometimes there is nothing we can do – despite our best efforts our vehicles seem to become magnetized targets for birds.

If your car has fallen victim to an assault by a thoughtless bird, time is your enemy. You’ll want to clean the residue off your vehicle as fast as possible to prevent damage, especially if it’s a hot day. Hopefully your car has recently been waxed, or better yet, you have had a ceramic coating applied to protect your clear coat.

If it is too late, and etching from bird droppings has already taken place, don’t panic. Depending on the type of etching (topical, wrinkle, or fracture), your paint will be able to be fixed by a professional paint shop. At Island Color, we can assess the damage and figure out the best way to get your vehicle looking brand new again. We are able to use the latest and greatest tools and technology, combined with decades of experience, to give you a seamless repair.

Give us a call or send us a note – we’re always happy to chat.

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