Car Paint Defects and How to Find Them

Sometimes, it’s just nice to drive out to your favorite spot on a weekend and enjoy a cup of joe, leaning against your car, not a care in the world. The scene is very relaxing—that is, until you spill some of that coffee onto the car’s paintwork.

Did you know that the acidity in coffee and most sodas is high enough to
strip away the clear coat of your car’s paint job?

For car aficionados like us, it’s important to understand the signs and causes of the most common car paint defects for us to avoid or fix them. This article will discuss the different kinds of paint defects in cars, what they look like, how to spot them, how to avoid them and how to fix them.

Why Should You Be Interested in Car Paint Defects?

If you’re on our website in the first place, it means you value your vehicle to a certain degree. Whether you drive a sleek sports coupe, a luxury SUV or a vintage piece, you don’t want anything spoiling its paint job.

Not only is fixing these defects tedious and potentially costly, but it can be upsetting seeing the paintwork damaged, especially when you’re trying to preserve its appearance.

This is why it’s critical that you are not only well-versed in engines, suspension kits, interior finishes and the like. You should also have a good understanding of your car’s paintwork and how it can be damaged. Recognising and identifying what paint defects are present on your vehicle helps you determine how to address them and what practices you should avoid to prevent them from happening again.

With the right information about car paint defects, you can choose the kind of procedure, equipment and product to use to repair them.

What is a Paint-Thickness Gauge?

From the name itself, this is a device used to measure the thickness of your car’s paint. It typically uses mil as the unit of measurement. One mil is equal to one-thousandth of an inch (0.001 in) or 0.0254 mm. Some devices have the option to switch to microns as the unit. One micron is one-millionth of a meter or 1/1000 of a millimeter, which is significantly smaller than a mil.

A paint-thickness gauge is essential to establish the severity of paint defects accurately. This information is used to determine the extent of the detailing needed to fix it.

For example, polishing or buffing is only usually done on the car’s clear coat, which is about 50 microns thick or about as thick as two sheets of cigarette cellophane wrappers. Dealing with these kinds of thicknesses requires the precision of the paint-thickness gauge.

While you can definitely tell which scratches are deep and shallow by feel alone, the paint-thickness gauge gives you additional confidence when identifying defects and their corresponding fixes.

What are the Types of Paint Defects?

Bonded Contaminants

Sand, road debris, soil and other tiny particles may get stuck in the clear coat of the car’s paintwork. Sometimes, they become embedded deeply enough that no amount of scrubbing during a typical carwash can get them out. They are also invisible to the naked eye most of the time.

Here are the common examples of this kind of car paint defect:

• Dirt/Debris – This can be identified by rough, irregular areas on the paint that can be felt by hand. In some cases, the particles can be embedded in the clear coat and even covered by film. Dirt and debris can get trapped when the washcloths used are not clean or when not all the contaminants have been removed before respraying.
• Overspray – When the panels are poorly masked during spraying, paint particles adhere to the surface of the film. They appear as granular areas of color on top of the clear coat.
• Contamination – These are spots or speckles staining the paint surface. These defects may be caused by metallic particles becoming stuck on the surface of the paint and oxidising. They can also result from salts left behind when liquids have evaporated.

Topical Paint Defects

“Topical paint defects” is a broad term that describes milder scratches and marks on a car’s paint job. They usually only occur above or on top of the clear coat. These defects can also typically be corrected using traditional methods like clay bar scrubbing or light polishing.

The following are the most common topical paint defects in cars:

• Polishing Marks – These are usually shallow marks caused by abrasive brushing, compounding or polishing, especially before the surface layer has fully hardened. It can also be caused by using too much pressure on the machine polisher or pads that may be dirty or too harsh. We’ve discussed machine polishing at length in another article. It should help you avoid these marks.
• Fine Scratch – This is a general name for shallow cuts that only penetrate up to the car’s clear coat. Fine scratches can be caused by anything from brushing into bushes to clothing buttons abrading the paint’s surface. These can also be addressed using machine polishing techniques.

To prevent topical paint defects, extra care should always be taken. To add another layer of protection, we suggest covering the car’s paintwork with paint protection film or PPF. This layer absorbs the most common types of impact and abrasions from everyday use.

Deep Paint Defects

As the name implies, these defects occur deeper than the car’s clear coat. This makes it difficult, and often, costly to address these. While chemical decontamination may work on some of these defects, heavy machine polishing is also usually required. In some cases, a respray may be the only way to correct these issues.

Here are some of the common deep paint defects:

• Stone Chips – These are damaged or broken parts of the paint film with varying depths, based on the extent of the impact. These are usually caused by a strong impact like a stone flying from loose road surfaces. Most of these chips happen when the car is driving at high speeds. However, falling debris can also cause these chips on stationary or slow-moving vehicles.
• Flaking – This happens when parts of the paintwork lose adhesion and lift from the underlying surface in smooth flakes. The flakes are easily broken or peeled away from the surface. The most common cause of flaking is the contamination of the underlying surface through corrosion or other chemical reactions.
• Cracking – These can be seen as crevices or breaks in the paint film. Cracking is usually caused by inherent problems during the paint application process that have been made worse by the elements.

It’s crucial to correctly determine whether the defect reaches deeper layers of the paintwork before a fix is decided on. The experienced eye of a car detailing specialist may be needed to find out whether polishing or respraying is in order.

Chemical Issues

Certain chemical reactions or agents can cause issues in the car’s paint job, whether during the application process or even after years of use. These are often magnified by hot or cold weather, especially if the car is frequently exposed to the elements. Many protectants on the market today, like ceramic coating, PPF or some waxes, have properties to shield cars from these issues.

These are the most common chemical car paint defects:

• Acid Reaction – These appear as patches of roughened or discolored paint surfaces that also appear stripped. In some cases, there may also be cracking on the surface. This is usually caused by spillage of acidic or corrosive substances like brake fluid, battery acid and even sodas and coffee.
• Chalking – A chalky, dusty or powdery paint surface is often associated with ageing paintwork, when the binding agent or the pigment layer starts to degrade. However, chalking can also be caused by defective or incompatible materials within the paint mixture.
• Yellowing – While most paintwork on today’s cars has some kind of UV protection, acid rain, engine heat and other causes may weaken the clear coat enough that oxidation happens in the mixture. This results in yellowing of the surface. Thorough washing, clay bar scrubbing and machine polishing can address this issue.

Application or Detailing Issues

Some issues are caused by poor application or detailing practices. Even newly bought vehicles are not necessarily free from these issues. Some new car paint defects are subtle and need a certain degree of knowledge in the matter to find.

Here are the most common paint defects that come from application or detailing:

• Slow Drying – Slow drying defects are parts of the paintwork that noticeably have not dried out completely. This happens when the paint applied is excessively thick. Poor conditions like coldness or humidity during paint application can also cause this problem. In some cases, a coat of paint may not have been given enough time to dry before the next one was added.
• Sanding Scratch – During a respray, if the metal substrate has not been sanded smooth, the paint may show dips that follow the contours of the scratches made to the underlying surface. This can also happen if the abrasive used on the metal substrate is too coarse.
• Blooming – This can be seen as a white or milky haze on the surface of the paint. It’s usually caused by inferior thinner quality or poor practices when using thinner. It can also be a result of humid, wet or cold conditions during paint application. Using the right grade thinner and avoiding non-ideal conditions during application can prevent this.

Takeaway

While the vehicle paint defects included in this article are only the common ones, there are many more kinds. PPG Industries prepared a comprehensive list of these defects for further information. Understanding how these issues occur can help you address them and prevent them from happening in the future.

If you’re unsure whether there are paint defects in your car’s paintwork, it’s best to have professionals at RR Purity take a look. We’ll be happy to give you advice or even better, we can address any kind of paint defect and restore the shine of your car’s paint. We also offer car paint protection services.

You can request a quote from us or get in touch by calling 07930042042.