Tuesday, 14 September 2010

Sacrificial Protection

Bird excrement paint surface etching

      Bird excrement damage (magnified)

A fundamental question first; what does a paint surface need to be protected from; after all we should ascertain what we are trying to protect against. Environmental damage to paint comes in a varied range of threats; acid rain, road salt, bird and insect excrement, tree resin (sap) hydrazine an extremely active acid that is found in jet or diesel fuel, industrial fallout, ultra violet radiation (UV-A and B) and other airborne contaminants are very detrimental to a vehicles paint film surface.

Acid rain (sulphur dioxide plus moisture) and is caused by sulphur from impurities in fossil fuels and nitrogen from the air combining with oxygen to form sulphur dioxide and nitrogen dioxide. These diffuse into the atmosphere and react with water to form sulphuric and nitric acids which are soluble and fall with the rain. Some hydrochloric acid is also formed.

Bird and Insect Excrement - comprises; Ammonia and urine as white crystals of uric acid (pH 3.0 - 4.5) a small organic compound, which is produced by the breakdown of protein during digestion, and is excreted by reptiles and birds. Uric acid is also the end product of nitrogen catabolism in birds Ammonia is a mixture of nitrogen gas and hydrogen gas; with moisture as a catalyst it becomes Ammonium Hydroxide, which is caustic.

Brake Dust - ferrous oxide (FeO) produced from the friction of brake pad material (semi-metallic, carbon resins, asbestos or ceramics formulations) rubbing against the rotor. The brake material friction as well as metal particles from the rotor disperses tiny particles of black dust, which forms a cohesive bond to the wheels and adheres to localized paint surfaces. Ferrous oxide micro-sized particles that come into contact with moisture will form rust.

Bug Residue and Carcasses - the carcass is very acidic, and if left for any length of time will cause the porous clear coat to occlude (a non-transparent ‘clouded’ area) or may cause etching (a depression in the paint or glass surfaces)

Calcium (Ca) - an untimely lawn sprinkler, a springtime shower, or spots that remained after washing, the minerals are white calcium/sodium deposits that are alkaline-based, especially from hard water. If left on the vehicle paint surface they act the same way as acid rain in that they will etch the paint film surface.

Contaminants - particles of dirt, grime, carbon emissions from catalytic converters, bird excrement, calcium, tar, oil, hard water deposits, calcium or any pollutant type substance that adheres to your paint surface, sometimes invisible the naked eye.

Corrosion (metal oxidation) - salt water conducts electricity better than fresh water so in areas that use salt on the roads, this process is greatly accelerated. Corrosion (rust) destroys metal by an electro-chemical reaction with water as the catalyst (water + ozone (an oxidizer) moisture + oxygen).

Detergents -. are usually a blend of several surfactants, which are two opposing polar groups, hydrophilic and a non-polar group lipophilic. Surfactants use emulsification to dissolve and encapsulate oily particles. Paint surface protection (wax, polymers, coatings, etc) are formulated to be detergent resistant, but be cognizant that the harsh high alkaline detergents used in high street carwash, especially no-touch tunnel wash will strip away a large percentage of wax and a percentage of polymer sealant, leaving the sacrificial barrier compromised

Hydrazine - an extremely active acid that is found in jet fuel, vehicles that park in close proximity to airports or flight-paths are subject to this contaminant. Park near idling diesels or an airport with a lot of jet fuel exhaust in the air; kerosene strips waxes or sealant; diesel and jet fuels are refined kerosene.

Infrared Radiation – (UV-A) wavelength or infrared radiation represents a part of the ultra violet solar spectrum (approximately 55%-60%). The remaining heat source comes from visible and ultra violet light

Heat alone will not cause photosynthesis (fading) UV-B radiation is what is responsible, although it 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 and may lead to structural damage (this is especially relevant to open top convertibles)

Industrial Fallout (IFO) - emissions from power generation, manufacturing plants and combustion engines emit Sulphuric acid from their exhaust stacks etc, vehicular catalytic converters emit carbon compounds that mixed with ozone (an oxidizer) and water becomes Sulphuric acid.

Oxidation - UV- B radiation is known to contribute to the chemical modification of exposed surfaces resulting in loss of gloss, colour change, chalking, flaking and eventually destruction of the paint film

Pollen - the yellow fines to coarse powders you see in the air is made up of small sperm cells from blooming plants and is one of the most common allergy triggers. The pollen from trees are the main concern, vehicles get hit with pollen laced trees that include: oak, western red cedar, elm, birch, ash, hickory, polar, sycamore, maple, cypress and walnut (which also leaves an oily residue). Pollen grains of pines, firs, and spruces are winged.

Road Salt - Although salt is inert when subjected to freezing (15 – 20.oF ) it’s considered the lower limit for salt to melt snow/ice but once H2O, even in the form of moist air (i.e. humidity) is added the freezing point is lowered and the saline solution(salt/water) will have an adverse effect on the vehicles paint and undercarriage.

When washing the vehicle ensure that all salt is removed to avoid a saline solution remaining on the paint finish. Using a durable protection (Collinite Insulator Wax) will provide a sacrificial and renewable protection to the vehicles paint finish.

Rail Dust - ferrous oxide (FeO) a black-colored powder that is created by railroad wheels abrading the metal tracks, these small particles become airborne and are sintered to the paint film surfaces. New cars that are transported by rail are at extra risk. When moisture combines with the oxide particles it creates small rust spots.

Ultra violet radiation –  (UV-B) (Light) 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 degradation results in discoloration, fading, embitterment, cracking, chalking and/or loss of mechanical properties. Ordinary auto window glass filters out about 95% of UV-A radiation.

Tree resin (sap) - appears like a dark brown/ rust red colour raised surface mark, some of the most common resinous tree sap types are: White Pine, Ponderosa Pine, Walnut (also secretes an oily residue) Maple, Oak, Popular, and Blue Spruce, none of which are water soluble, the acidic content of the sap will etch the paint surface; causing a concave surface.

Water - beading that is left to evaporate on a car will lead to water marks; a standard household supply usually contains alkali minerals like calcium(Ca) magnesium (Mg), which are inert until heat and moisture is added and then it become corrosive. Once these form a ‘bead’ and they dry they will cause etching (a shallow indentation) of the paint surface. Clean rainwater (See also Acid Rain) has no harmful effects. The average unprotected water-based paint absorbs approximately a pint of water; dependent upon its content this may be harmful.


Quite a formidable list but all these have a few things in common; they are all forms of environmental contamination and given the right catalyst; reactivity (heat) plus moisture, they will become acidic. During this process the metal absorbs oxygen from the water and forms iron oxide (rust). Given the porosity of paint they permeate the paint matrix down to body metal.

The good or at least better news is that an organic wax will provide a sacrificial barrier i.e. it provides (time) limited protection and also absorbs the acid, which can then be wiped off and then renewed. It should be noted that any wax subjected to an acidic attack (bird excrement, etc) must be removed without delay otherwise the paint surface will be compromised.

Sacrificial Protection

sac•ri•fi•cial [:designed to be used up or destroyed]

A paint or metal surfaces natural sacrificial protection is oxidation; the so called white rust on aluminium is in fact oxidation. Eventually, any mechanical abrasive action will wear away the oxidation; this could be caused by washing the paint surface, using a car duster, placing or removing a car cover, etc.

The micro thin layer of wax or polymer sealant, apart from their aesthetic qualities provides a film that resists the adhesion of dirt and etc and allow you to wash the paint surface without using undue pressure, thereby micro marring the paint. Be cognizant that they are limited in their ability to resist scratches, although some Finish Kare FK1000P for instance provides better protection than most.

Products like Klasse an acrylic polymer is acid based and is resistant to acidic attack, or an inorganic wax like Collinite 845 Insulator Wax or Finish Kare FK1000P is probably the most durable inorganic wax product, but this will only provide enough of a barrier to enable it to be removed quickly before causing too much (etching) damage to the paint film

The latest nanotechnology coating or PPG CeramiClear™ Clear Coat although they are highly resistant to chemicals, detergents, scratches and ultra violet radiation (UV) will only offer limited resistance to acid etching from environmental contaminates. The newer nanotechnology coatings are better than conventional last step products (LSP) i.e. Aquartz silica coating. Although there are no products to-date that can protect against bird excrement or other environmental acids

Carnauba wax forms a multi strata matrix, whereas a polymer is a mono layer that cross-links and forms a chain like structure that forms a molecular bond to the paint surface. Contaminants will be further removed from the surfaces that are protected with a Carnaubas multi strata matrix than with polymers mono (single) layer

Wax coatings act as a sacrificial buffer between a paint surface and the elements; these coatings are gradually used up (hence sacrificial) and reach a point where they can no longer protect; when they reach this point they must be renewed. Once attacked by acid (acid rain, Bird or Insect excrement, Industrial fallout, and etc) it should be removed and a fresh coating applied.

No wax, polymer sealant or nanotechnology coating on its own, can provide a permanent shield against acidic attack from bird excrement, acid rain etc as they are all incompatible with strong acids.

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 (UV-B) degradation, and is a common problem in products exposed to sunlight.

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