Ultra Violet (UV) Radiation Damage

[togwt]

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. Infrared radiation (IR) 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. Ultra violet radiation (UV- exposure leads to gloss and colour instability (photo degradation 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 photo-oxidation (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. 25µ layer of the clear coat paint. Removing more that 12.5µ (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)





Photo degradation



[: decomposition of a compound by radiant energy] a common reaction is oxidation.



Today’s water-based products have a number of obvious environmental benefits, but some are more susceptible to photo degradation (fading) over time, a significant drawback. In addition, because of ozone depletion, higher levels of solar ultra violet (UV) radiation now reach the surface of the earth. This further contributes to the rate of fading.



Polymers use in auto paint, plastics and vinyl, where they are routinely exposed to sunlight; the UV radiation adversely the mechanical properties of these materials, often causing structural failure, which limits their useful life.



Photo-oxidation of polymers



Sometimes incorrectly described as photo degeneration, is the degradation of a polymer surface in the presence of ozone. Oxidation is the way a polymer protects the under laying paint by acting as a sacrificial layer. This is a consequence of ultra violet (UV) radiation, which instigates a chemical change that reduces the polymer`s molecular weight.



As a consequence of this change the material becomes brittle, with a reduction in its tensile, impact and elongation strength. Discoloration, a chalky appearance and loss of surface smoothness accompany photo-oxidation. Infra red (IR) radiation or high surface temperature significantly increases the effect of photo-oxidation.



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] [1]



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

[imported_DetailDan]

Can you go into any detail on how UV radiation affects interiors on modern cars. It seems the glass already filters out the majority of UV rays already.

[togwt]

New car owners mistakenly believe their new vehicle cannot be damaged by sun exposure. Due to the ozone layer depletion (global warming) in our atmosphere, UV radiation strength is increasing. Protecting your vehicle from UV radiation damage continues to be a very important.



Ultra Violet Protection



Ultra violet penetration of auto glass; UV radiation is present in the sun’s rays throughout the year in varying amounts. Ordinary glass is partially transparent to UV-A but is opaque to shorter wavelengths, auto window glass filters out about 97% of the UV radiation, the cause of photo degeneration (fading) and approximately 37% of infrared (UV) (heat ) radiation.



1. Infrared Radiation (UV-A) long wave length



Infrared radiation (UV-A) is a light source that transmits heat that will cause oxidation by drying out materials, like the paint (binder) resin system, the plasticizers in vinyl, moisture evaporation of leather and the elasticity of rubber causing these materials to dry out and become brittle and compromise their structural integrity



Heat will also dry out the oils and plasticizers in vinyl and other materials. It will dehydrate leather and may lead to structural damage (this is especially relevant to open top convertibles)



Dependent upon interior colour - at a 90.oF ambient; with a (Light) 104 - 135.oF or (Dark) 220 – 275.oF interior



Steering wheel – 160.oF - Dashboard 182.oF - Seats 165.oF (dependent upon colour and material) actual results may vary depending on time in sun, size of windows and direction of the suns Azimuth and the angle relevant to it that the car is parked.



Heat will dry the resin (binder system) in paint; leading to oxidation. It will also dry out the oils and plasticizers in vinyl and other materials. It will dehydrate leather and may lead to structural damage (this is especially relevant to open top convertibles)



Ultra violet radiation (UV-



Short wave ultraviolet light (UV- is known to contribute to the chemical modification, photo degeneration (fading) of outdoor exposed materials, resulting structural damage, loss of gloss, colour change, chalking, flaking and along with infrared heat radiation (UV-A) eventually the destruction of the clear coat paint film.



Ultra violet stabilizer -Ultra violet light (UV- radiation and environmental contaminant exposure leads to photo degradation of materials and surface staining. 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 light more readily than other materials.



Be cognizant that ultra violet heat (UV) radiation can also affect the structural integrity of materials by drying out and therefore removing their elasticity and causing structural damage (cracking).



There is no such thing as a permanent UV stabilizer, it a matter of physics, not chemistry. Ultra violet protection is a sacrificial and therefore a renewable protection; this is due to the UV protection layer being degraded by exposure to the elements (sun, sand, road or sea salt, and etc) so it is imperative that you renew it and it needs to be re-applied on a regular 45 to 60 day basis (dependent upon location climatic condition)



The following are things you can do to provide protection-



• Use a polymer paint sealant product on your car several times each year. A carnauba wax, contrary to popular myth (or is it marketing BS) doesn’t contain inbuilt UV protection. This sacrificial protections effectiveness lasts for no more than 2-3 months.

• Use a vinyl and rubber protectant with UV inhibitors on all exterior vinyl and rubber twice a month.

• Protect fabric and leather upholstery and carpet (especially in a roadster) with a UV and stain blocker treatment twice a year.

• Use a sun shield in your windshield when parked outside.

• Cover your car when parked outside for extended periods.

These simple measures will ensure your vehicle`s appearance has a chance of remaining in excellent condition for ten or more years. If you take no precautions, its appearance will noticeably deteriorate in less than five years