The term hydrophobic refers to molecules and surfaces that repel water. Water on hydrophobic surfaces such as oil will exhibit a high contact angle, which is used to quantify the wettability of a solid surface by a liquid.
Surface contact angle
As shown in the figure above, there is a direct relationship between surface contact angle and how well water beads up on a surface. For example, car wash drying aids that contain mineral oil have a contact angle of about 80 degrees. Water repellants and sealants will have a contact angle approaching 100 degrees.
Applications containing carnauba wax or synthetic wax will create a contact angle of 110 degrees or more.
At issue with these coatings is durability. The structure that wax and sealant depend on for their repellence is easily damaged by abrasion and cleaning. Therefore, constant re-application is needed to maintain a high degree of performance (i.e., up to 30 days).
Ceramic or super-hydrophobic products are available in the car wash and detail industry. Super-hydrophobic is described as a nanoscopic surface layer that repels water. Such surfaces have a contact angle approaching 150 degrees. So, droplets hitting this kind of coating appear to fully rebound.
Super-hydrophobic coatings are made from different materials but silica-based coatings are often the most cost effective. A silica-based gel for vehicles is a two-step process involving surface preparation and then application via aerosol spray or wipe-on, dry, and buff.
There are also paint sealants made with polysiloxane, a silicone-based polymer. These products bond to paint and create a more permanent barrier, which increases gloss and paint film thickness.
AT THE CAR WASH
More recently, “ceramic” products have been introduced for online application at automated car wash operations (e.g., Turtle Wax Super Hard Finish). Like drying agents, ceramic products are mixed with water and applied to vehicles through a standing arch.
Although most online ceramic products have proprietary labeling, I did find one safety data sheet that listed ingredients. Not surprisingly, what’s inside is similar to other car wash products such as surfactant, foam booster, inexpensive solvent with properties of surfactant, ammonium salts, and amine oxide.
According to one manufacturer, the magic ingredient that makes their ceramic product almost miraculously and exceptionally effective is a silica-based material. Such materials are known to have a surface contact angle approaching 150 degrees.
Since an online ceramic coating does not actually form a film-like gel-based product, we would expect constant re-application similar to hydrophobic wax and sealant to maintain performance.
According to the CleanTouch website, the company’s Ceramic Glaze offers protection against all types of environmental elements and lasts up to 45 days once applied to a vehicle’s surface.
Other attributes of the product are described as making insects and bird droppings easy to remove, increased paint gloss, and outstanding drying quality.
The safety data sheet for Ceramic Glaze states the composition or material ingredient is a silicone microemulsion (10 - 20 average percentage weight). The specific chemical identity and/or percentage of components are withheld as a trade secret.
Microemulsion is defined as clear, thermodynamically stable, isotropic liquid mixtures of oil, water, and surfactant with dispersed domain diameter varying approximately from 1 to 100 nanometers.
How well does the online ceramic product work?
As a consumer, I’ve found the online ceramic product is better than either rain repellent or hot wax in terms of drying quality, shine, and longevity.
As advertised, it did seem as though our car didn’t get dirty as quickly and it was easier to clean the next time — and subsequent times.
Of course, like most good products, ceramic coating technology has come to the masses in the form of aftermarket products made by brands such as Meguair’s, Mothers, etc.
For example, Meguiar’s Hybrid Ceramic Wax uses Si02 technology. Surprisingly, the product is applied as it is in a commercial car wash. After washing the vehicle and rinsing off the soap, the product is sprayed on the surface and then rinsed off with water. The final rinse helps to spread and lay down the product evenly. The vehicle is then dried with a microfiber towel. No buffing required.
Mothers CMX Ceramic Spray Coating is a little different. It uses a SiO2 (Silicon Dioxide) and TiO2 (Titanium Dioxide) blend. After washing and drying the vehicle, the product is sprayed on an applicator pad and then wiped on the surface. It buffs off easily with a microfiber towel. According to Mothers, layering can be done after curing for 24 hours.
Since the material forms a bond, towels have to be washed immediately to avoid being clogged up.
How well does it work?
After my neighbor began using Meguiar’s Hybrid Ceramic for his car, he came over and gave me all his Meguiar’s liquid express cleaner/wax.
I asked him where he learned about spray-on ceramic products and he told me from the mobile detailer that he uses occasionally. The detailer said ceramics is a game changer.
Quite possibly he’s right.
Many car wash operators today are keen on selling value as in the most products for the least amount of money (e.g., free vacuums, monthly unlimited washing).
Conversely, when selling something like ceramic coatings, product features need to be described and tied-in someway that they improve the customer’s situation (e.g., lasts 45 days, stays clean longer, easier to clean, etc.). Since ceramic promises to be a game changer, it will be interesting to see how the industry bridges the gap between selling value and benefits.
Most likely, the next frontier for the car wash industry will be an ultra-hydrophobic product. Such a product would produce a surface contact angle far exceeding 150 degrees and would be extremely difficult to wet.
Basically, paint would react like a lotus-plant leaf — a droplet of water would fully rebound and bounce and roll off the surface. Such a product could be sold as easy-to-clean or self-cleaning. Arguably, such products may present something of a paradox to car wash operators.
First of all, hydrophobicity is not additive. In other words, drying aid (80 degrees) plus total body (105 degrees) equal 105 degrees not 185. Consequently, a super-hydrophobic product would make the familiar sequence of extra-pay online protectant seemingly redundant.
Constant re-application is always attractive from a supplier’s perspective just as the unlimited wash option is to consumers. However, one has to wonder if, when, and how consumers will adjust their purchasing behavior when products promise exceptional benefits and longevity such as “easier to keep clean” and “easier to clean next time.”
More recent, has been the development of an aftermarket clear-coat paint that promises even greater benefits. For example, DVG™ (dvgbrands.com) has introduced SUPERCLEAR™, which is described as glamour paint and billed as the world’s first self-healing and self-cleaning clear coat.
Unlike the DIY ceramic products discussed earlier, Superclear is a high-quality clear-coat paint that is sprayed over an OEM clear coat after first lightly wet sanding it down.
The list of features is impressive: Superclear provides a self-cleaning surface, it’s self-healing at ambient temperatures, it has a high gloss level, it has high solids content making it 50 percent more scratch resistant than OEM paint, and it allows for flow coating for a glass-like finish.
Flow coating is a painting technique to avoid polishing by applying two wet coats of paint with 50 percent overlap. In fact, the limited warranty states that the product must be applied by a certified installer (i.e., a professional auto body shop).
It isn’t cheap either. The one-quart kit is priced at $500 online. However, unlike the ceramic gels and spray-on products we mentioned that wear off, the effects produced with Superclear are permanent for the life of the paint.
Consequently, Superclear (patent pending) promises to greatly reduce the need for vehicle upkeep and maintenance such as car washing and waxing.
In the final analysis, car wash operators shouldn’t be threatened by this product because it isn’t intended for the mass market. However, its development underscores where the industry may be heading in the future.