Surface Tension: A Discussion of How Wax & Automotive Ceramic Nano Coatings Function in Auto Detailing.
By Christopher Brown of OCDCarCare Los Angeles – OCDCarCare.com – 17 Jan 2017
Surface Tension, What on Earth is that?
Surface Tension, in auto detailing terms, is the discussion of how particles of water or contaminants interact with a vehicle’s surface; usually paint.Typically, this subject is approached in conversations around how water and dust particles have a hard time sitting on or clinging to a surface. In auto detailing, this is a positive surface attribute because high surface tension causes water beading, water sheeting, and helps vehicle surfaces to remain cleaner — for longer periods of time. In terms of ceramic paint coatings, surface tension is crucial because these properties explain many of the key benefits which paint coatings provide, while also providing insights to detailers which can help when troubleshooting potential surface issues.
Surface Tension Definition
In the auto detailing community, surface tension discussions tend to be glossed over or skirted around. Typically, the subject appears to be most discussed in the context of coating manufacturers defining the contact angle of a particular product. While this is a concept that is crucial to the effect of surface tension; it does not provide a full picture of how surface tension functions, nor does it explain to detailers what actually occurs at the surface level in terms of a surface tension with a measurement of “X.”
Contact angle defined, without overly technical language: The lower the contact angle number, the easier for a liquid to ‘wet’ a surface by spreading out over it. A high contact angle describes the effect seen when liquid drops seem to sit or dance on top of surfaces; such as winter shoes treated with scotch-guard or water staying in tight beads on top of a waxed vehicle. The higher the contact angle, the less surface area individual drops of liquid share with their surface. A very high contact angle causes liquid drops to almost appear as complete spheres on top of a surface.
Most simply: contact angle quantifies the ‘wettability’ of a solid surface by a liquid.
How Surface Tension is Relevant and Important in Auto Detailing
Surface Tension 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 tension is even more relevant today, than it was even 4-5 years ago, since ceramic paint coatings have become a staple surface protection option. Therefore, detailers need a solid understanding of the technology and properties behind coatings as well as the relevant issues that may arise around ceramic nano coating upkeep and maintenance.
This article came to fruition because little to no information or resource regarding this subject exists to educate consumers or detailers. This article’s concepts primarily focus toward the performance and characteristics of ceramic nano coatings. However, MOST of this information is applicable to the understanding behind surface characteristics for all Last Stage Products (LSP’s); including waxes and sealants.
How Surface Tension Causes Hydrophobic Surface Behavior
ALL LSP’s including Waxes, Sealants, and Ceramic Nano (aka Glass) Coatings were partially engineered to protect vehicles by keeping surfaces clean. The amount of surface tension an LSP creates accounts for its ability to repel contaminants and liquid off of vehicle surfaces. Surface tension is also the scientific component which causes wax to bead and ceramic coatings to sheet water. The industry 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 surface tension 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 remain hydrophobic for extended periods of time.
In regards to 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 coating “failure” is due to topical contamination or something else layered on top of the coating, altering the surface characteristics.
To Layer, or not to Layer Ceramic Nano Coatings or Waxes?
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, creating a gorgeous presence. However, if a vehicle has a ceramic nano coating applied to its surface, then even this impressively handsome wax is NOT the product you wish to keep on top of it; either for maintenance or as an additional sacrificial barrier of protection.
The ONLY thing you want to top a coating with is a long term silica sealant or another semi permanent coating product which are commonly referred to as ‘toppers.’ Preferably, any topper product should remain in the same chemical family as the base paint coating. Remaining within a chemical family helps to maintain continuity of surface tension and ensures optimal adhesion of the topical product, while retaining the original properties that base coating provides. Putting anything else over a ceramic paint coating, other than these types of topper products, alters the surface tension. As stated previously, many protection characteristics of a paint coating depend on the ability to remain hydrophobic. And this ability is maintained through high surface tension.
The Fickle Nature of Coating Surface Tension
The surface tension, and most of the measurable performance characteristics, of ceramic paint coatings are quite fickle if not maintained. It is actually quite simple to drastically alter the surface tension of a coating or anything automotive related. This is the exact reason why most coatings companies insist/stress regular wash intervals for coated surfaces. With regular maintenance, coating properties remain optimal, allowing vehicle owners the ability 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 paint coating technology. This occurs because the coating maintains the outermost surface tension. Therefore, adding anything with completely different chemical compositions and differing surface properties is highly inadvisable.
The Detailing Industry and Misinterpretations of Surface Tension Behavior
A change in surface tension alone is never a reliable indication of coating failure. Surface tension ‘failure’ could easily happen by smearing olive oil or a finish polish over a coated section. Whatever residue remaining after the wipe off alters the surface behavior of that coated section. Therefore, this example only indicates that surface tension has shifted from the ideal characteristics of the coating. It does not mean the coating has failed, but rather it hydrophobic properties are masked.
Often, customers or detailers form snap judgements or conclusions about ceramic coating effectiveness or durability based on surface tension characteristics. Unfortunately, these opinions are without a true or full understanding of the principals behind vehicle surface tension. This type of uninformed dialogue is found on literally hundreds of online forums and social media groups, many times marketing related. Surface properties alone do not provide an accurate picture of a paint coating and its overall protection characteristics.
If a coating is not exhibiting perfect surface characteristics this does not mean its other protective qualities are also gone. Coating benefits and protective capabilities of: UV protection, chemical resistance, improved topical hardness, additional gloss, and measurable thickness; do not vanish if the surface does not sheet liquid. Unfortunately, and quite commonly, portions of the detailing community have judged and perpetuated the myth that a coating’s overall quality and durability relate to the surface performance. This is definitely not the case.
When a coating ‘fails,’ most times, topical surface contamination is the culprit. This contamination build up occurs for a number of reasons, but most frequently from improper wash intervals allowing contamination to layer and cover the coating’s surface. Detailers and consumers can avoid falling into the pitfalls of misjudging products with better knowledge. Therefore, the understanding of how surface tension affects surface longevity and performance is crucial.
Final Words on Surface Tension, Ceramic Paint Coatings, and Waxes in Auto Detailing
Vehicle surfaces require regular maintenance (washing) in order to keep them free of topical contamination. Proper vehicle surface maintenance optimizes the effects of ceramic nano coating water sheeting or the ‘super sexy’ tight beading of waxes. If contamination is allowed to build up, eventually it morphs into the outer most layer of a vehicle’s surface. Therefore, the paint adopts the surface tension properties of this outermost contamination layer. Does this mean a ceramic coating or wax is gone or has failed? No, not necessarily. Most likely it indicates the surface is contaminated and therefore masking the properties of the LSP.
Next time you think a ceramic nano coating or wax is ‘bad’ or has ‘failed’, consider the vehicle’s surface tension. Surface tension always plays a critical role in surface care within automotive detailing. However, when armed with an understanding of the science and properties associated with surface tension, detailers are better suited to troubleshoot possible surface issues.
~Keep on Buffin’
© Christopher Brown of OCDCarCare Los Angeles – OCDCarCare.com – 2017
For more auto detailing and car care related topics please browse: OCDCarCare Los Angeles’s – Auto Detailing Article Archive.
His passion & dedication to car care lead him to writing in-depth articles about detailing related subjects in order to share and interact with the car enthusiast & detailing communities. Eventually, this lead to detailing training courses designed to develop skills, confidence, and results which enable detailers to increase quality, efficiency, and profitability.
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