Light Reflectance

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Light Reflection

Reflection of light may be specular (that is, mirror-like) or diffuse (that is, not retaining the image, only the energy) depending on the nature of the interface. It is also possible for reflection to occur from the surface of transparent media, such as water or glass.


Specular reflection – [: law of reflection says that for smooth surfaces, the angle at which light is incident on the surface equals the angle at which it is reflected] the perfect, mirror-like reflection of light from a surface, in which light from a single incoming direction is reflected into a single outgoing direction. The best example of specular reflection is seen when reflected from a flat level surface


Diffuse reflection – [: incoming light is reflected in a broad range of directions] When light strikes a rough or granular surface, it bounces off in all directions due to the microscopic irregularities of the surface. The most familiar example of the distinction between specular and diffuse reflection would be glossy and matte paints. While both exhibit a combination of specular and diffuse reflection, matte paints has a higher proportion of diffuse reflection and glossy paints have a greater proportion of specular reflection.


If the surface is perfectly flat, light will be reflected to produce a mirror image of the subject. But if there are imperfections such as swirls, orange peel, or oxidation (dull opaque paint) light is refracted and the subject is distorted. The oils that are formulated in Carnauba waxes provide gloss, which causes jetting (a ‘wetting’ of the surface) this distorts the light reflectance, giving the surface the ‘look’ of rippling liquidity, like a mirror in shallow water reflecting a three-dimensional deep, rich colour, in contrast, bees wax, paraffin and many synthetic waxes and some polymer sealants (Zaino is one exception) tend to occlude (become opaque) as there is little optical clarity


  • Reflective Value (RV) [:a measurement commonly used in interior decorating and design, which expresses the percentage of light that is reflected from a surface] The reflective value (RV) of a colour indicates how much light and heat is reflected back from the colour surface. Light reflectance value (RV) is a numerical rating assigned by paint manufacturers to each colour they make. This number is a scientifically determined assessment of the amount light and heat that colour will reflect on a scale of 0 to 100. Zero assumed to be an absolute black and 100% being an assumed perfectly reflective white.

An absolute black or perfectly reflecting white do not exist in our everyday terms. The average blackest black has a LRV of approximately 5% and the whitest white is approximately 85%. Some yellows can measure up into the 80's or 90's as well. All colours fit in between these two extremes. A colour with an LRV of 50 will reflect 50% of the light that falls on it, and one with an LRV of 23 will reflect 23% of the light, and so on. Think of a reflective value as a numerical version of a grey value scale for colours, roughly like this:


  • Colour / Reflective Value

Pure White / 100, White / 95, Light / 80, Low Light / 65, Medium / 50, High Dark /35, Dark / 20 Black / 5, Absolute Black / 0


* Colour, Depth and Clarity- the three factors concours judges look for when scrutinizing paint film surfaces. So much depends on proper surface preparation, a clean and level surface, and product clarity, which allow the natural gloss of the paint to show through, as without transparency the true colours of the paint surface cannot be seen. Waxing a surface that has not been properly cleaned will only result in a shiny layer over dull, dirty paint - not the deep smooth, optically perfect crystalline shine that is obtainable.


An Optically perfect shine- comes from a clean, prepared and level surface; it improves the desired optical properties i.e. surface reflectance. The other requirements are surface gloss, depth of shine and applied product transparency (clarity), which allows all of the components of an optically perfect shine to be visible.

•Is the result of combining an optically clear polymer sealant for its reflective shine properties with a Carnaubas three-dimensional jetting properties.

•The best light reflection is obtained from a perfectly flat highly reflective surface, i.e. glass over a silver metallic material –a mirror

•A polish would need to level a paint surface; this will provide a surface without distortion

•To provide protection to our theoretically perfectly distortion-free surface we would need to apply a wax or a polymer sealant, which in turn would need to be optically clear


Shine - is an easily understood concept of light reflection / refraction (in simple terms the light reflectance from a mirror) I wanted to expand that concept so that the shine would be optically perfect as well as multi-dimensional. The bright shine of a polymer sealant is often criticized as being “sterile” (a flat silvery-white reflection) good reflective properties but without ‘depth’.


The oils that are formulated in Carnauba waxes provide gloss, which causes jetting (a ‘wetting’ of the surface) this distorts the light reflectance, giving the surface the ‘look’ of rippling liquidity, like a mirror in shallow water reflecting a three-dimensional deep, rich colour, in contrast, bees wax, paraffin and many synthetic waxes and polymer sealants tend to occlude (cloud)


The aesthetics- of a vehicles appearance is very subjective to say the least, the only best wax or sealant that really matters is what looks 'best' to you. In the final analysis it all come down to; 85% preparation, 5% product, 7% application method and the balance is in the ‘guy’ of the beholder

In obtaining the ‘optically perfect shine’ we should be equally concerned with ease of application, resistance to abrasion, atmospheric contamination and weathering. Products should be chosen that would carefully balance each of these considerations without focusing on one specific characteristic. A surface protection with a spectacular shine but limited durability just doesn’t make sense.


* a) Requirements:


•Clean-washed to remove oxidation, surface dirt and grime, tar and road film


•Reflectivity – that comes from a clean and level surface


•Gloss-that comes from oils and polymers with there ability to reflect light with a minimum of light diffusion to produce surface shine


•Optical depth-comes from an applied product that is two-dimensional, so that light is reflected from both a high and low source, (i.e. a Carnauba waxes ‘egg-grate’ type structure) as opposed to a polymer elongated and flat ‘chain-link’ type mesh, which ‘distorts’ reflected light to produce a rippling effect (warmth)


•Optimising light refraction -apply product in ‘direction of airflow’, horizontal surfaces hood to trunk, vertical surfaces front to back. This application technique affects the paints optical properties by optimising light refraction and the reflectivity of the bodylines and contours of the vehicle


•Transparency-or clarity of the applied product, which will enable all the above components to be clearly visible


b)Contributing factors:


•Cleaned- using a mildly alkaline (pH 7.5) car wash concentrates to remove surface road dirt and grime and then- using detailer’s clay to remove ingrained pollution from the paint surface, and a chemical paint cleaner (Klasse All-In-One) to prepare the surface for a polymer sealant and a Carnauba wax.


•Polished-removal of minor blemishes, surface scratches, swirl marks and water marks with an abrasive machine polish or compound (Menzerna) to provide a level surface. A machine polish should remove surface imperfections and swirl marks, contain oils for lubrication and should not leave residue that requires extensive ‘clean-up’ to remove hazing, its solvents should evaporate moderately quickly without leaving excess wax/oils behind, and lastly should buff relatively easily.


•Glazed- to obtain a high gloss by providing the necessary oils and burnishing the paint surface to a high optically clear gloss


•Protected- the polymers carrier system (solvents) allows the product to fill and level the paint film surface to produce an ultra-flat surface while proving durable surface protection. A polymer (Zanio Z2PRO™) with its levels of shine, gloss, clarity, reflectivity, depth and 99% optical clarity, which doesn’t distort or detract from the paints colour or lines of the vehicle.


•Waxed-the applications of Carnauba (Souveran Paste Wax) that will provide oils to provide a ‘wet-look’ to the surface and will also provide a transparent surface when layered without yellowing or discoloration, with a depth of shine by providing a two-dimensional surface.


•Light coloured paint -i.e. Silver, White, etc (the exception is speed yellow) will never obtain jetting (the so called ‘wet-look’) of black or dark colours as they do not exhibit visible depth, light colours tends to reflect light instead of absorbing it and providing a 2-dimentional look. You can obtain a good gloss provided the paint is good quality and if it’s prepared and detailed correctly; washed, cleaned, polished and a polymer sealant added (Zaino, Klasse AIO and SG, Jeffswerkstatt - Acrylic Jett ) these sealants will provide a flat silvery-white shine, but without ‘depth’ the exception is Zaino Clear Seal (Z-CS).


By adding a Carnauba wax or a Glaze as an LSP (Pinnacle Souverän Paste Carnauba or Autoglym Super Resin Polish or Danase Wet Glaze) the oils and / or polymers that are formulated in the Carnauba waxes provide a reflective gloss, which causes jetting (a ‘wetting’ of the surface) For optimal results the surface of a light coloured paint to show gloss is very much dependant upon good / excellent paint condition, adequately prepped to remove contaminants and minor imperfections. Detailer’s clay (Sonus SFX Ultra-Fine Detailing Clay Bar) and / or Paint cleaner (Zaino PC or Klasse AIO) should be a regular part of the preparation process


Information resource

1.Wikipedia - http://en.wikipedia.org/wiki/Main_Page

2.Automotive Detailing Inside & Out, A Knowledge Base for the Perfectionist– Jon Miller

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