Oxidation [: oxygen is added to a molecule with an electron being displaced, which in turn dries the paints binder system]. UV radiation is known to contribute to the chemical modification of exposed paint surfaces resulting in loss of gloss, color change, chalking, flaking and eventually destruction of the paint film When UV light is absorbed it starts a chemical reaction that begins to cleave (break) the chemical bonds of the resin binder system, causing them to overheat and dry out, or it can also be caused by excessive (friction) heat generated during the machine polishing process. Leaving microscopic surface imperfections and micro fissures in the paint film surface that are vulnerable to deterioration. Once the air borne contaminates and pollution compromises the paint surface they accelerate the oxidation (reduction) or paint failure process, which leads to bleaching (fading), discoloration, chalking, brittleness and cracking - all indications of UV deterioration. Once a paint surface structural integrity is compromised like this it usually means the paint requires replacement (re-painting) A chalk like appearance on the paint surface or small triangular marks (crow’s feet) or other similar marks on the paint surface - basically the chemical integrity of the paint has been degraded by ultra violet (UV) radiation, stress, environment fall out and etc. Oxidation really amounts to a weakening of the resins that bind paint, which results in the micro-pores becoming exposed and a larger area of paint becomes oxidized. Once the paint has been breached in this manner, applying waxes and polishes temporarily wets the surface making it appear better. The oils and other components do not have the ability to repair the resin binders but rather cover up the problem for a short period of time. What happens when paint oxidizes? Think of these polymer matrixes as being chains of molecules which get their strength from the bonds that hold them together, they have one unalterable characteristic...they are chains that are only as strong as their weakest link. That’s why the reactivity is so important in urethanes. Reactivity is the chemical process that makes those linkages; break the link at any point and you begin to weaken the chain that gives a coating its protective capabilities. Un-reacted bonds are “weak links” from the beginning. Thermal, photo- degradation, mechanical, chemical, and biological degradation bring about changes in physical properties in polymers. They disturb or weaken the links that give the chain its integrity. There are other stress agents like airborne pollution, salt, sand, abrasion, solvents, biological contaminants, acidic or alkaline substances, chlorides, etc. that also add stress. But, as damaging as they are, they are only contributory elements leading to polymer bond failure, or as some call it “polymer unzipping” because of the similarity to a zipper being unfastened. Ultra violet radiation, moisture migration and how they interact with each other. Let’s start with sunlight induced damage known ultra violet (UV) radiation Perhaps you’ve read about how “free radicals” are bad for you and how anti-oxidants of whatever kind (foods, vitamins, and supplements) will control them and prevent damage to your body. Well, the same free radicals apply to paint as well. First understand polymer backbones are made up of multiple elements. Key among these is hydrogen and oxygen. When the coating absorbs photons of UV radiation from sunlight, some of the energy “excites” the binder’s molecules to a higher energy level and causes bond cleavage, like a hot knife through the molecule’s heart. The result is free radicals. Free radicals are simply scavengers trying to steal an electron from a weaker molecule that has one. They react with oxygen in the air to create oxygen radicals, which then attack the polymer backbone. In so doing, hydrogen atoms break from the coating to form hydrogen radicals and more free radicals. This is where a vicious cycle begins. The free radicals combine with oxygen again to form a chain reaction. More and more molecular links break; leading eventually to failure of the coating’s properties. Remember the demonstration of a nuclear chain reaction, where they had a room full of mousetraps all loaded with a ping-pong or golf ball. They threw a ball into the room and triggered a chain reaction. It took a slow motion camera to see clearly all the balls going off everywhere with increasing intensity. There you have, in its simplest form, the chain reaction that is photo-oxidation. Moisture accelerates this degradation through a chemical process called hydrolysis. Once again, the process involves hydrogen when the splitting of a bond causes a reaction between the hydrogen from the coating and the hydroxide from the water (H2O). Finally, the infrared heat energy from the sun comes into play, expanding and contracting the coating during a 24-hour cycle, causing accelerating stress fatigue degradation. High temperatures also accelerate the process of link breakage outlined in photo-oxidation. All these stress factors lead to one additional form of degradation, the porosity of the coating film. It’s like having an umbrella attacked with hairpins. The holes created are small and relatively insignificant until they become so numerous that the integrity of the umbrella (coating) is compromised. Once moisture, with all the contaminants it can bring along, and oxygen (that’s why they call it oxidation) gain access to the coating’s weak underbelly, the coating’s protective barrier (whether clear coated or not), is attacked from inside and under to devastating effect. An oxidizer- is any compound that spontaneously emits oxygen either at room temperature or under slight heating. Many chemical compounds react vigorously at ambient temperatures as the oxidizing process takes place. Oxidation is caused by environmental pollutants (acid rain, ozone, industrial pollutants, hydrocarbons, etc) the suns heat, which also causes paint colour fading from ultraviolet radiation (UVR) inclement weather or the use of harsh detergents, all of which attack the paints binder system(resin) It starts as a chemical reaction that causes the resin binder system to overheat and dry out, leaving microscopic surface imperfections and micro fissures in the paint film surface that are vulnerable to deterioration. Once the air borne contaminates and pollution compromises the paint surface they accelerate the oxidation (reduction) or paint failure process. Two- stage paint system- (base, colour and clear coat) A clear-coat finish does not oxidize in the true sense of the word; meaning that the pigments and resins mix together and the pigments are exposed to the sun's ultra-violet rays, which cause them to dry out, this is not oxidation, but clear coat failure. The clear coat is applied to protect against this but the finish will become ‘dull’ by using harsh (abrasive) or if acidic car washing solutions as used in ‘touch less’ car washing systems, or from industrial airborne pollutants compromising the clear coat allowing the suns heat to dry out the paints resin binder system. The clear coat layer is extremely thin (1.5 – 2.0 Mils) it is not a solid coating and is to some extent porous, oxygen interacts with substances in the paint layer (i.e. mica flakes as in metallic paints) and trigger the oxidation reaction. It's just that the amount of oxidation taking place is minimal in comparison to single stage paint. For oxidized paint try the following (this is only a temporary ‘fix’) • Wash the paint surface and dry thoroughly • Clean the paint with chemical paint cleaner (Klasse All-In-One) using an Lake County (LC) orange foam pad at speed #4, this may take 2-3 applications • If a chemical paint cleaner doesn’t remove the oxidation use a (LC) purple foamed wool (PFW) pad and Menzerna’s Power Gloss (POS 34A) clean or replace with a clean pad as the oxidized paint will load the pad • A foam pad will transfer kinetic (friction) heat to the paint and may exasperate the problem • Using Gloss It EVP Pad Prime will help maintain sufficient oil lubrication for the polish • Wet-sanding will remove ‘oxidation’ debris, which may remove too much clear coat • Once the oxidation has been removed use a decontamination system (Aquartz Iron Cut) • Apply an oil rich product to stabilize the paints binder system (3M Imperial Hand Glaze) apply a thick coat and allow to dwell for 12-24 hours before buffing, repeat as necessary until surface has an ‘oily’ sheen. • Remove residue and apply a synthetic wax that contains both Carnauba wax (oils) and a polymer sealant (1z Einszett Glanz Wax Hart Glanz) and then a polymer (for heat protection) paint sealant. • Try to keep vehicle paint surface away from UV heat radiation • Keep paint surface waxed on a regular basis. Single-stage paint systems (base and colour coat) – (note-single stage paint is usually very ‘soft’) without a clear coat to provide protection, primarily a hostile environment will attack the paint surface causing microscopic gaps and valleys (micro fissures) and it becomes compromised both chemically; by industrial fallout (IFO) acid rain, brake /rail dust and etc., and by UV heat radiation, which causes it to dry out and/or fail, causing the clear coat to expand and often separate from the base coat, allowing environmental pollutants to penetrate. Acids enter the breach formed in the clear coat and attack the resin binder system, which accelerates the degrading of the paint film surface, eventually leading to oxidation and/or failure. Oxidation can appear as a dull and somewhat hazy, or `chalky' appearance to the paint surface, a paint film surface that is adequately protected with wax or a sealant actually has a lower surface temperature than one that is not. An extract from one of a series of unbiased Detailing Technical Papers, a library of educational materials that has become the #1 reference for car care on the Internet Chances are you'll learn something about detailing if you read any of these; although these articles will not improve your detailing skills, lead to a successful business or change your life. Applying what you learn from it, however, will. That's where your commitment comes in - you need to make a commitment to yourself right now that you will take action on what you learn. © TOGWT ™ Ltd Copyright 2002-2010, all rights reserved {EDITED}
