How Ceramic Coatings Work: Detailing Hydrophobic Science Explained

High Surface Tension from auto detailing training article by OCDCarCare Los Angeles.

By Christopher Brown of OCDCarCare.com

Automotive Ceramic Nano Coating Hydrophobics (Water Behavior) . . .

Ever Wonder HOW it works to:

  • Makes car washing so fast and easy?
  • Keeps Vehicles looking cleaner for longer?

. . . The Answer lies in a scientific concept: Surface Free Energy.

Surface Energy a.k.a. Hydrophobics a.k.a. Water Behavior: What on Earth is that?

Surface Energy, in auto detailing terms, is the discussion of how water or contaminants interact with a vehicle’s surface. Typically, this subject appears in conversations surrounding the ability of water and dust particles to rest on a surface.

Within general car care or vehicle cleaning, this is good because low Surface Energy causes water beading, water sheeting, and helps vehicle surfaces to remain cleaner.

In terms of ceramic paint coatings, Surface Energy is crucial because it explains key benefits which coatings provide to automotive surfaces. Understanding surface energy allows to better understand, maintain, and troubleshoot potential ceramic coating surface issues.

This is quite important with professional auto detailers. Many times detailers believe ceramic coatings have “failed” when the hydrophobic properties of a coating have diminished or  stopped. The water behavior of a surface is dependent on many factors, not just the coating itself.

Read on to learn about the fickle nature of hydrophobicity and how water behavior influences one aspect of ceramic coating protection.

Ceramic Coating Hydrophobic Properties: Terms & Concepts Defined

Surface Energy

Surface energy is a measure of a solid’s surface state.

High Surface Energy means a liquid will have great success adhering to that surface. Think of a pool of water on a sidewalk.

Low Surface Energy means a liquid has difficulty adhering or sticking to a surface, causing it to fall off the surface with relative ease. Think of droplets of water on an umbrella.

Contact Angle

Contact Angle measures how a liquid interacts with the surface energy of a solid surface. The higher the contact angle measurement, the more difficulty a liquid has adhering to a solid surface.

Contact angle is measured between a liquid droplet’s edge and the solid surface it rests upon. At a very high contact angle, say 145 degrees, water almost appears as three quarters of sphere sitting on top of a surface. Therefore, only a small portion of the liquid droplet touches the solid surface. At a low contact angle, say 30 degrees, water appears as a small wide pool, touching (wetting) the surface.

Most simply: contact angle quantifies the ‘wettability’ of a solid surface by a liquid.

Sliding Angle

Sliding Angle measures how easily water releases (slides) off of a surface. Specifically it measures the angle at which a drop of water begins to fall down an incline. The lower the sliding angle the easier it is for water, and any topical contamination, to release off of a surface.

Sliding angle is arguably more important than contact angle for ceramic nano coatings, because it indicates how easy a vehicle will be to clean. This translates into many aspects of protection and automotive surface care, including helping to avoid hard water spots left from minerals of water and the ‘self cleaning effect’ ability of a coating formulation.

Hydrophobic

The terms Hydrophobic and Hydrophilic use contact angle to define how a solid surface interacts with liquid.

Hydrophobic translates to “fear of water.” A surface is Hydrophobic when liquid contacting it contains a contact angle of 90 degrees or greater. Hydrophobic surfaces are hard to wet.

Hydrophilic

On the other hand, Hydrophilic means “friend of water.” Hydrophilic surfaces have water contact angles below 90 degrees.

Think of pouring water onto a typical sidewalk. The water easily rests onto the concrete. There is almost no discernible difference between the water and the concrete. They seem to fuse together to make — wet concrete. That is a hydrophilic surface.

How is Surface Energy Relevant and Important in Auto Detailing?

Surface Free Energy of automotive surfaces is a topic rarely discussed, yet carries much significance in today’s detailing climate. Without an understanding of this concept, it may be difficult for detailers to evaluate and plan solutions for common auto detailing issues arising from the behavior characteristics of vehicle surfaces.

Surface Energy (hydrophobic properties or ‘water behavior’) is even more relevant today than ever, since ceramic nano coatings are a staple surface protection option. Therefore, detailers need a solid understanding of the technology and properties behind ceramic nano coatings. This knowledge may prove invaluable for relevant issues that may arise around ceramic nano coating upkeep and maintenance.

This article was written because little to no information or resource regarding hydrophobic properties (water behavior) exists to educate vehicle owners, consumers, or auto detailers.

This article’s concepts primarily focus toward the performance and characteristics of ceramic nano coatings. However, MOST of this information is applicable to understanding the surface characteristics for all Last Stage Products (LSP’s); including waxes and sealants.

How Topical Contamination Changes a Vehicle’s Hydrophobic Surface Behavior

ALL LSP’s including Waxes, Sealants, and Ceramic (aka Glass) Coatings were partially engineered to protect vehicles by keeping surfaces clean.

The amount of Surface Energy an LSP creates accounts for its ability to repel contaminants and liquid off of vehicle surfaces. Surface Energy scientifically explains how wax ‘beads’ and ceramic coatings ‘sheet’ water.

The common detailing term, often used to describe water beading or sheeting, is ‘hydrophobic;’ literally meaning afraid of water.

When anything layers on top of an LSP; such as dirt, topical contamination, or another product, the Hydrophobic properties of that LSP can change. Regular vehicle wash schedules assist in keeping vehicle surfaces clear of contaminants. This is the only way to ensure surfaces retain their LSP’s hydrophobic properties for extended periods of time.

In regards to ceramic coatings specifically; often the public, or even some detailers, quickly proclaim a coating has failed when it stops sheeting water. This is not entirely the case when investigating the matter at a surface level.

Most times, a proclaimed coating “failure” is due to topical contamination resting or bonding on top of the coating. This contamination may drastically alter the surface energy characteristics of the surface, masking most or all water behavior.

Low Surface Tension from auto detailing training article by Christopher Brown of OCDCarCare Los Angeles.

High Surface Energy. This surface accepts liquid and is therefore ‘wettable’ meaning liquid has the ability to dwell on the surface.

Proper Products to “Layer” or “Top” a Ceramic Nano Coating With…

As a wax, Swissvax Concourso is a stunning choice for automotive finishing. Its high carnauba content causes vehicles to glow with a sexy cinematic halo around them.

However, if a vehicle has a ceramic nano coating applied to its surface, then wax is NOT the correct product to maintain it with. Even if the intent is to add an additional sacrificial barrier of protection.

The ONLY thing to ‘layer’ or ‘top’ a coating with is a long term silica sealant or another semi permanent coating product. It is Highly Recommended, that any topper product should remain in the same chemical family as the ceramic coating. Remaining within a chemical family helps ensure the water behavior maintains continuity of surface energy from the base coating and ensures optimal adhesion of the topical product.

Putting anything else over a ceramic paint coating, other than these types of topper products, alters the surface energy.

As stated previously, some protection characteristics of a paint coating depend on the ability to remain hydrophobic. This ability is maintained through low surface energy. Using the wrong product on top of a coating can change the water behavior for the worse and negate some of the protection benefits a ceramic coating provides.

The Fickle Nature of Ceramic Coating Water Behavior

The hydrophobics (water behavior) of am automotive ceramic coating are the easiest performance characteristics to measure. However, they are extremely fickle if not maintained properly or are neglected for long periods of time.

It is actually quite simple to drastically alter the surface energy of a coating. This is the exact reason why most coatings companies insist/stress regular wash intervals for coated vehicle surfaces.

With a regular routine of car washing vehicle surfaces stay clean and smooth by avoiding topical bonded contamination. A regularly cleaned surface allows a coating’s water behavior to remain optimal, enabling vehicle owners and auto detailers to visibly identify the coating’s hydrophobic abilities.

Ease of maintenance and the ability to keep vehicle surfaces clean are prime benefits and selling points of ceramic nano coating technology. This occurs because the coating maintains its original intended outermost surface energy properties.

In short, wash your vehicle regularly to maintain an automotive ceramic coating’s water behavior.

For a more in-depth look into vehicle washing read our article “Detailing DIY How To: How Often Should I Wash my Car?

Auto Detailing and Misinterpretations of Ceramic Coating Water Behavior 

A change in surface free energy alone is never a reliable indication of coating failure.

Hydrophobic ‘failure’ could easily happen by smearing olive oil or a finish polish over a coated section. Whatever residue remained after wiping the surface would alter the water behavior of that coated section.

Therefore, this example only indicates that surface energy has shifted away from the ideal characteristics of the coating to the properties of the left over polish. This does not automatically mean coating failure, but rather its hydrophobic properties are masked by whatever was put on top of it. In this case, a finish polish.

Often, vehicle owners or detailers form snap judgements or conclusions about ceramic coating effectiveness or durability based on hydrophobic properties.

Frequently these opinions are without a true or full understanding of the principals behind vehicle surface energy. This type of uninformed dialogue floods literally hundreds of online forums and social media groups, many times marketing related.

Therefore, let’s set the record straight:

Hydrophobics, or Water Behavior, alone do not provide an accurate picture of automotive ceramic nano coatings and their overall protection characteristics.

Hydrophobics are one aspect in the overall protection offered by ceramic coatings.

When a coating ‘fails,’ to produce water beading or sheeting, most times topical surface contamination is the culprit. Contamination generally builds up from surface neglect.

When vehicle surfaces are NOT cleaned regularly, contamination layers form, and build on one another, like a brick wall over time. Eventually they build up to completely cover the coating’s surface. When this happens the hydrophobic properties of the vehicle surface adapt the contamination because it is the outer layer interacting with the environemnt.

This is why the understanding how surface energy affects hydrophobic characteristics, and how to maintain them through proper washing intervals, is critical to ceramic coating surface performance and longevity.

Final Words on Surface Energy, Ceramic Paint Coatings, and Waxes in Auto Detailing 

Vehicle surfaces require regular maintenance (washing) to keep them free of topical contamination. Clean surfaces optimize the effects of water behavior of ceramic nano coatings and waxes.

If surface contamination builds up enough it eventually becomes the vehicle’s surface. When this occurs vehicle surface adopts the surface energy properties of this outermost contamination layer.

This does not automatically mean a ceramic coating or wax has failed. Most likely, the surface is highly contaminated, therefore masking the hydrophobic behavior properties of the LSP.

If a coating exhibits poor water behavior, its other protective qualities are not automatically gone. A ceramic nano coating’s benefits and protective capabilities of: UV protection, chemical resistance, enhanced hardness,  gloss, and measurable thickness; do not vanish if the surface does not sheet liquid.

Unfortunately, this myth exists within the detailing world that a coating’s overall quality and durability relate directly to water behavior. Some even boldly proclaim complete coating failures within 6 months, due to a lack of hydrophobic water behavior. This is definitely not always the case.

**Warning: Next time you think a ceramic nano coating or wax is ‘bad’ or has ‘failed’, first consider the vehicle’s surface energy. Surface energy plays a critical role in surface care within automotive detailing. Understanding of the science, and properties associated, of surface energy will arm detailers with knowledge that will improve surface issue troubleshooting.

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For more auto detailing and car care related topics please browse: OCDCarCare Los Angeles’s – Auto Detailing Article Archive

Christopher Brown
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