Friday 9 January 2015

The Science behind Coatings


Probably the greatest impact has come from the use of micro technology coatings, which have completely changed the landscape of the detailing industry. Products like Zaino, Collinite, and etc. used to be the best protection available but micro technology products offer greatly extended durability, scratch resistance and protection from the elements that can be measured in seasons or years, as opposed to weeks or months.

A common element in a coating formula, Silicon dioxide (SiO2) also known as silica, is a chemical compound that is an oxide of silicon. Silica is most commonly found in nature as quartz.

Often misnamed as a glass coating, however glass is an amorphous (non-crystalline) solid material which is often transparent. Of the many silica-based glasses that exist, ordinary glazing and container glass is formed from a specific type called soda-lime glass, composed of approximately 75% silicon dioxide (SiO2), sodium oxide (Na2O) from sodium carbonate (Na2CO3), calcium oxide, (CaO), and several minor additives..


What is Nanotechnology as it relates to Detailing?

The science of nanotechnology; the creation, organization, or manipulation of materials, devices, or systems at the nanometre level Nanotechnology, Nano particles or Nano structures, exactly what are they and how do they relate to detailing?

Most of these coatings are not true nanotube/tubule technology. This would cause a serious health concern for all of those - not to mention be ridiculously expensive. The context that “nano" (as related to detailing) is only as a relative size indicator merely to identify a micro sized particulate. They are sub-micron particles that form a clear thin film of tightly packed nano particles forming an extension of the surface. The particles are up to a 1000 times denser which makes for an ultra-durable hard wearing surface.

Technically most detailing product particulates are not nano metre in size, although they are extremely small, as the term ‘nano’ adequately describes. Single-component coatings interlace on a molecular basis and form an extremely durable protective layer on the paint surface provided they are applied properly.


The significance of a nano-coating is its micro sized particles that can form a very tight bond with the surface of most materials; including glass, paint, plastic, rubber, aluminium, chrome, stainless steel and fabrics. These materials will have surface imperfections i.e. peaks and valleys, micro-fissures when viewed under high magnification. These undulations allow a nano-coating polymer to form a tight molecular bond (much like a printer’s powdered ink when poured over paper that has writing indentations on it) with the surface it’s applied to. 

Paint Surfaces

Automotive paint surfaces contain microscopic peaks and valleys, much like the profile of a mountain range. These irregularities are known as capillary structures; there may be millions of these defects per square inch. Contaminants such as fine dirt, minerals, and pollutants are drawn into the voids where they are extremely hard to remove.

The filling of the capillary structures with micro particles produces a hydrophobic surface. (A hydrophobic surface is one that repels moisture.) In contrast, a hydrophilic surface is one that absorbs moisture. The potential of a surface to absorb or repel moisture is based on many factors, including: temperature, relative humidity, material homogeneity, and static electricity. Surface roughness is also a major factor; the rougher the surface, the higher the spreading rate or attraction for water. The smoother the surface, the more repellent it is to moisture (Lotus Effect).
The significance of a micro coating is its small particle size that  can form a very tight bond with the surface of most materials; including glass, paint, plastic, rubber, aluminium, chrome, stainless steel and  fabrics, will have surface imperfections i.e. micro-fissures when viewed under high magnification. These undulations allow a micro coatings to form a tight molecular bond (much like a printers ink when poured over paper that has writing indentations on it) with the surface it’s applied to This level surface also improves paint surface clarity and reduce light scattering, providing improved light reflectance (LRV)
Sealing a surface with micro particles means applying a micro structure onto the surface, these treated surfaces become hydrophobic and resists road dirt, grime and etc. attaching to its surface by the ‘Lotus Effect’. It is therefore highly water repellent, which enables less effort during the cleaning stages and optimum protection to the paintwork, glass, alloys, fabric and trim.
Micro technology coatings form a very tight matrix chain-link micro structure  that comprises a clear thin film of tightly packed nano particles forming an extension of the surface. These very dense particles are both a very strong bond and one that is not easily breached by chemicals or detergents. They also improve paint surface clarity and reduce light scattering, providing improved light reflectance
Through self-organizing anti adhesion components, the micro structure forms an invisible barrier similar to glass. They form a bond by lodging themselves into the micro pores of the paint forming an anchored foundation and then this foundation is built upon to form the nano particle matrix. This is why a clean and dry, oil-free (micro pore) surface is so important. Only the micro structure remains on the sealed surfaces, while the water evaporates.

Micro technology offers superior durability, hydrophobicity, surface hardness and scratch resistance, resistance to environmental contaminants, works like a clear coat in providing ultra violet (UV) and heat radiation protection without colour change (yellowing) or oxidation and easier maintenance, simply rinsing with plain water results in a clean surface without loss of gloss. these products are having a profound impact and radically change auto detailing

Paint sealants compared to Coatings

Paint sealants are synthetic products designed for long-term paint protection and easy application. They are composed mainly of amino functional polymers, which last longer than any natural wax and are highly resistant to the elements. Synthetic liquid waxes are another way of describing paint sealants. The main benefit of a paint sealant is their durability compared to a wax, polymer-based sealants will last anywhere from 3 to 6 months.
A coating is applied to a clean surface and are capable of  a micro structure 'film build', that is to say a measurable thickness, that surface takes on properties that are virtually identical to hardened glass. It is chemically inert and will not react with the base material. In other words, dirt will not bond to the treated surface, thereby reducing soiling and organic staining. Acid rain and other chemical compounds easily wash off, significantly reducing the hydroscopic nature of surfaces exposed to industrial or environmental pollution.


Does paint density (hardness) affect its scratch resistance?

Many coating products claim an obtained surface (Pencil) hardness of 9H but this has little if anything to do with scratch resistance. Scratch resistance can be related to higher cross-link density and elasticity of the coating network.
Some Nanotechnology Coating products

·         AQuartz is an inorganic silica / silicon dioxide
·         DuPont's SupraShield™, PPG's Optech™ and CeramiClear™ are all inorganic silica               coating
·         Gtechniq is an inorganic silicate crystallization compound
·         Modesta is an inorganic Silicon dioxide (SiO2)
·         Nanolex is an inorganic, solvent-based nanostructure coating

·         Opti-Coating Pro is a silicon carbide (SiC) grains of silicon carbide are bonded together by      sintering to form a very hard ceramic



Hydrophobic surface [: The requirements for a self-cleaning hydrophobic surface are a very high static water contact angle θ, the condition often quoted is θ>160°, and a very low roll-off angle, i.e. the minimum inclination angle necessary for a droplet to roll off the surface] [1]




The lotus effect [: refers to self-cleaning properties that are a result of very high water repellence (super- hydrophobicity), as exhibited by the leaves of the lotus flower] Dirt particles are picked up by water droplets due to the micro architecture on the surface, which minimizes the droplet's adhesion to that surface

Hydrophobicity

Definition of both Water repellence (hydrophobicity) and Roll-off

Hydrophobic surface [: The requirements for a self-cleaning hydrophobic surface are a very high static water contact angle θ, the condition often quoted is θ>160°, and a very low roll-off angle, i.e. the minimum inclination angle necessary for a droplet to roll off the surface] [1]

Hydrophobicity [: the property of being water-repellent; tending to repel and not absorb water is determined by the contact angle]

A hydrophobic surface is one that repels moisture. In contrast, a hydrophilic surface is one that absorbs moisture. The potential of a surface to absorb or repel moisture is based on many factors, including: temperature, relative humidity, material homogeneity, and static electricity. Surface roughness is also a major factor; the rougher the surface, the higher the spreading rate or attraction for water. The smoother the surface, the more repellent it is to moisture. 




Contact angle

The contact angle [: is the angle measured through the liquid, where a liquid/vapour interface meets a solid surface. It quantifies the wettability of a solid surface by a liquid via the Young equation]

Contact angle measurement provides a simple way to determine the level of surface protection. The formation of large, closely spaced water droplets demonstrates that moisture is effectively prevented from being absorbed (a hydrophobic surface) into the surface profile. The classification of water droplets on a hard surface is known in industry as a “water break test” or ASTM F-22. This test is used extensively in the industry to check surface cleanliness.

The size, shape, and height of the water droplets are measured by their contact angle. Contact angle is figured by a straight line that starts at the base of the droplet and travels along its outer surface to the break-off point. The measurement between this line and the surface determines the contact angle

Surfaces with a contact angle A 90° are referred to as hydrophilic and those with an angle A90° as hydrophobic. Some plants show contact angles up to 160° and are called super-hydrophobic meaning that only 2-3% of a drop's surface is in contact. Plants with a double structured surface like the lotus can reach a contact angle of 170° whereas a droplet’s actual contact area is only 0.6%. All this leads to a self-cleaning effect.

Roll-off

The lotus effect [: refers to self-cleaning properties that are a result of very high water repellence (super- hydrophobicity), as exhibited by the leaves of the lotus flower]

Repellant [: able to repel a particular thing; impervious to a particular substance]

Roll off of dirt particles with a reduced contact area are encapsulated by water droplets and are easily cleaned off the surface. If a water droplet rolls across such a contaminated surface the adhesion between the dirt particles and the water droplet is very much reduced and the dirt is easily removed from the surface



Surface energy [: defined as the excess energy at the surface of a material compared to the bulk or the work per unit area done by the force that creates the new surface]

Coating Viability

Surface energy (interface energy) [: in the physics of solids, surfaces must be intrinsically less energetically favourable than the bulk of a material (the molecules on the surface have more energy compared with the molecules in the bulk of the material]

In order to successfully form a continuous coating, the liquid should be able to wet the surface of the material. Wettability depends on one specific property of the surface: surface energy. The surface energy of the solid substrate directly affects how well a liquid wets the surface. To achieve good wettability the surface energy of the substrate needs to exceed that of the surface tension of the liquid by around 2 - 10 mN/m (Dynes). The Dyne level reflects the surface wettability - the higher the Dyne level, the better the wettability/adhesion.

To obtain optimum adhesion, it is necessary to increase the surface energy of the substrate to just above that of the material to be applied. For optimum adhesion of a coating on various substrates, it is necessary to obtain a high surface energy. Determining the surface energy can be achieved by measuring contact angle or by use of Surface Energy Test Liquids or Pens (Dyne level testing).

This form of measurement is based on the ISO method for measuring the surface energy of polyethylene film. Surface energy may be defined as the excess energy at the surface of a material compared to the bulk.  Every solid surface has a specific and measurable surface energy.  The unit of measurement used is the Dyne/cm² or mN/m.

When the Dyne level test liquid is applied to the surface, the liquid will either form a continuous film on the surface or pull back into small droplets. If the Dyne test fluid remains as a film for 3 seconds, the substrate will have a minimum surface energy of that fluid value, expressed in N/m (Dynes). Should the Dyne test fluid reticulate or draw back into droplets in less than 1 second then the surface energy of the substrate is lower than that of the fluid itself. To test the viability of a coating requires measuring the surface energy (surface tension).

Using a Dyne Test Pen will measure the surface tension and identify whither the coating is still viable, which requires a surface tension of 38mN/m or higher.

Measure the surface energy by using slight pressure to draw the Dyne QuickTest Pen tip across the coated surface. If the ink lines shrink or bead within 1-2 seconds then the surface protection is degrading as the surface energy level has dropped to less than 38 Dynes. If the ink lines remain as marked and do not shrink then the test sample surface protection is still viable as the coating has a surface energy of 38 Dynes or higher.

Dyne QuickTest Pen - http://www.dynetechnology.co.uk/measurement-equipment/quick-test-pens/

Product Application

Be cognizant that for a coating product to reach its full potential; that is to say the correct contact angle, durability and optimum cross-linking it imperative that you provide a ‘clean’ surface. Prior to application both above and sub-surfaces should be decontaminates, polishing lubrication (oils, polymer (silicones) and wax) system should be removed

Use the appropriate personal protection equipment (PPE) an approved mask (Consult the current 3M Respiratory Selection Guide for additional information or call 1-800-243-4630 for 3M technical assistance) nitrile gloves and safety glasses as a minimum.


Due to the construction of micro fibre towels, they comprise a hydrophobic Polyester (a scrubbing fibre) which also gives the material strength and durability and a hydrophilic Polyamide (an absorbing fibre) that is tremendously absorbent and quick drying. This nylon hybrid is created during weaving to create microscopic loops, which form a network of tiny hooks, scrubbing away dirt and grime.  The nature of this yarn is that it is an absorbent; the reason polyester appears to absorb liquids is the many thousands of micro fibres that collectively encapsulate liquids.

1)       Dr Joe dedicated Lint-Free 100% Cotton Surgical Towels, that  have a lint free, tight cotton herringbone weave and a thread count of 170  per square inch,  which is ideal for hard surfaces as they have more ‘grip’ than micro fibre towels and helps to spread the coatings evenly.Fold the towel in half and then half again.

2)       The coating can also be applied with a lint-free and non-abrasive microfiber suede cloths (very low nap), which will evenly spread the coating as opposed to absorbing it. Edgeless optical grade suede weave Use a fresh cloth with an applicator block to help you lay down the perfect application of liquid coatings and other protection products. The Rag Company Detail Master™ Pro but the major disadvantage of this type of application is the coating dries and solidifies to glass, which means you need 5- 8 towels that will be discarded after use.

My preferred application method is to use base coating (P-01A) applied with a rotary machine polisher and apply the coating with a spray gun as I feel this gives a consistent thickness and coverage. The coating can be applied with a micro fibre towel but the major disadvantage of this type of application is the coating dries and solidifies to glass, which means you need 5- 8 towels that will be discarded after use.



Drying / Curing

Use of infra-red lamps is highly recommended. Allow 24 hours in a moisture / dust free environment

Coating Maintenance

Many people have the incorrect impression that paint coatings are a “no maintenance required” type of product.  This is simply not true.  Routine washing is crucial.  As your coating becomes covered with dirt and contamination, you will notice a decrease in hydrophobic properties. It’s important to remove any surface contaminates on a regular basis with a car wash concentrate that will not leave gloss enhancers or surfactants behind due to a coatings ‘roll off’ washing and drying the paint surface is very easily accomplished

The normal car wash concentrates mostly contain surfactants and alkaline additives. They work by breaking down surface tension and wetting the surface to facilitate soil removal by flushing. With many of the newer coatings traditional car wash solutions, especially at their normal extreme dilutions.

Use a specially formulated product like Optimum ONR or Modesta H-05 Shampoo– specifically formulated for hydrophilic coatings. This special shampoo removes dirt and restores/prolongs the coating’s original hydrophobicity. This is an ideal coating maintenance shampoo

Dry surfaces with a waffle weave (pique) towels to ensure zero marring to the paint surface

Summary

Polish the paint surface to remove (without removing too much clear coat) any surface imperfections as this product cures to become optically clear and will highlight any surface defects. It has always puzzled me why people over-polish their car paint and cause the paint to fail prematurely; we all have seen examples of clear coat failure. A coating is the most effective way to avoid premature failure of clear coats.

Coatings offers superior durability, hydrophobicity, surface hardness and scratch resistance, resistance to environmental contaminants and works in a similar way to a clear coat in providing ultra violet (UV) and heat radiation protection without colour change (yellowing) or oxidation and easier maintenance, simply rinsing with plain water results in a clean surface without loss of gloss. I think these products will have a profound impact and radically change auto detailing

Bibliography

1.        Royal Society of Chemistry (RSC) Library & Information Centre
2.        Glossary of Chemical Terms - Faculty of Chemical Technology
3.        Basic Concepts of Nanotechnology, History of Nano-Technology, News, Materials and Potential Risks
4.        Lotus-inspired nanotechnology applications, B. Karthick1  and Ramesh Maheshwari
5.        SpecialChem4 Polymers
6.        Macromolecular Chemistry and Physics
7.        European Coatings Handbook 2nd Edition, by Brock, Groteklaes, Mischke
8.        Bayer Material Science, Automotive  eNewsletters (Coating, Adhesives and Specialties)

The information in this article is based on the current status of the technical development as well as our experience with the products.

Foot Note:

I carried out extensive laboratory testing of coatings utilizing standard lab protocols, this entailed chemical analysis with a mass spectrometer, heat, acid and ultra violet radiation resistance, surface hardness and hydrophilic properties.

The mas spec analysis showed many similarities between some brands, which not surprisingly would suggest relabeled products.

The few, just let’s say unique, products although using completely different chemicals in their formulation exhibited outstanding results


Filing a patent on a chemical formulation is extremely difficult and would not solve the problem as changing just one component would make the patent void. Change is what R and D (development) is all about, and besides relabeled product in the final analysis results in more sales.



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