Ultra violet Radiation is known to contribute to the chemical modification of exposed paint surfaces resulting in loss of gloss, colour change, chalking, flaking and eventually destruction of the clear coat paint film by oxidation. Ultra violet protection is a sacrificial / renewable component; this is due to the UV protection layer (stabilizers) being degraded by exposure to the elements (sun, sand, road or sea salt, and etc) it is also water miscible, so it is imperative that you renew it and needs to be re-applied on a regular basis (dependent upon location climatic condition)



There is no such thing as a permanent UV stabilizer, it a matter of physics, not chemistry. Ultra violet protection is a sacrificial and necessarily renewable protection. Acrylic polymers and polyurethane polymer are slow to absorb UV light and accordingly somewhat resistant to photo degradation.



Many natural and synthetic materials are attacked by ultra-violet radiation and products made using these materials may crack or disintegrate. This problem is known as ultra violet degradation, and is a common problem in products exposed to sunlight.



1. UV-A radiation (ultra violet light) dries out the binder system causing structural failure; it will dry the resin in paint; leading to oxidation. A paint surface will often show cracking as the resin binder dries out the paint draws up on itself forming ‘crow’s feet’. It will also dry out the oils and plasticizers in vinyl and other materials and may lead to structural damage (this is especially relevant to open top convertibles)



2. UV-B radiation (infrared heat) exposure leads to gloss and colour instability (photosynthesis or photo-oxidation) and surface fading stains. But before UV light can cause harm, it must first be absorbed. If it is not turned into heat or transferred to a nearby stabilizer molecule called a quencher, it breaks weak chemical bonds. This is the beginning of UV damage. Some materials absorb UV radiation more readily than other materials. Materials that readily absorb (UV- radiation are quickly damaged...rubber, vinyl’s, gel coat fibreglass, and many other plastics.



When radiation is absorbed, it starts to break (cleave) weak chemical bonds, which leads to photochemical degradation (bleaching, (fading), discoloration, chalking, brittleness and cracking) all indications of UV deterioration. The bond cleavages resulting from UV absorption cause the formation of “radicals.” Each free radical can trigger a chain of reactions (in the presence of air), leading to more bond cleavages and destruction. These oxidising chain reactions require no further UV exposure, just the presence of air



The clear coat provides gloss plus physical protection from the elements, including ultraviolet (UV) radiation, which is in the upper 1.0 – 1. 25 layer of the clear coat paint. Removing more that 12.5 (0.5 mil) of clear coat will precipitate premature paint film failure as the ultra violet (UV) protection percolates to the top of the clear coat, there is ultra violet (UV) protection all the way through the paint, but the majority of it migrates to the top of the clear coat along with the thinner solvents and particles.



Therefore removing clear coat ultra violet protection is not a linear process; by removing a small percentage of the clear coat paint tends to remove a larger percentage of UV inhibitors. So once you remove too much clear coat you`ll have no paint UV protection other than what you apply with a LSP (See also Environmental Pollutants)



Ultra Violet Photosynthesis



UV radiation is a paint film surface`s greatest enemy, causing more damage than any other airborne contaminant and affecting both the interior and exterior of a vehicle. The light in this spectral range is responsible for photo degradation.



Photo photosynthesis (UV- degradation results in discoloration, fading, embitterment, cracking, chalking and/or loss of mechanical properties. Chalking gel coat fibreglass, yellowing plastics, fading and weakening fabrics and sunburned skin are all familiar problems caused by UV-B radiation. Infrared radiation (UV-A) is a light source that transmits heat that when combined with a UV-B radiation source will cause oxidation by drying out the material.



Before ultra violet radiation can cause harm, it must first be absorbed. If it is not turned into heat or transferred to a nearby stabilizer molecule called a quencher, it breaks weak chemical bonds. This is the beginning of UV damage; some materials absorb UV light more readily than other materials.



Oxidation



The paint surface takes in a chalky grey appearance that has no shine. Basically the chemical integrity of the paint has been degraded by ultra violet (UV) radiation, acid rain, industrial fall out (IFO) 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. The paint top surface loses its reflective ability and becomes ‘chalky’; this is a sign that the structural integrity (mechanical strength) of the paints matrix has become compromised.



Once the paint has been breached in this manner, polishing with a chemical paint cleaner (Klasse AIO) may remove minor surface oxidation but use caution if you decide to use an abrasive polish, as you are further ‘thinning’ the paint, 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.



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 (UV-A), which cause them to dry out; this is not oxidation, but clear coat failure.

The clear coat, which contains ultra violet (UV) protection 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. 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) or Meguiar’s M105, 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 polymer coating (Opti-Coat™) for protection.

• Try to keep vehicle paint surface away from UV heat radiation

• Keep paint surface waxed on a regular basis.



Temporary remedy – wash and dry the surface, and then use a chemical paint cleaner (Klasse AIO)Check the paint thickness and there is sufficient thickness polish the surface (Meguiar’s M105)Apply a coating (Opti-Coat™) for protection



Clear Coat Failure



Delamination -[: the separation of a material into layers in a direction approximately parallel to the surface. The partial or complete separation of the layers of a laminate] Encyclo the on- line encyclopaedia



Extreme temperature fluctuations can cause the clear coat and the basecoat to delaminate. Basically the clear coat elasticity will react at differing rates during extreme temperature swings. This actually happens more often on areas of the surface where snow, ice, or frost accumulates. It can also be accelerated in areas that are subjected to rapid heat application, such as the engine hood, especially when the engine is subjected to strain i.e. towing another vehicle