Research from Autoglym
New research from Autoglym, the UK's leading car care experts, suggests that the familiar sight of car bodywork 'etched' by bird droppings are not the result of any corrosive property in the deposit, as is commonly believed. In fact, damage instead results from the paint lacquer contracting upon cooling and moulding to the uneven texture of the hardened deposit.

a) As paint lacquer warms – in the direct summer sunshine for example – it softens and expands. At the same time, that heat dries and hardens any bird droppings on the surface. Autoglym's researchers discovered that as the paint lacquer cools, overnight for example, it contracts, hardens and moulds around the texture of the bird dropping. To the naked eye, this moulding at a microscopic level appears as dulled or etched paintwork. The light's reflection is interrupted by the imperfect surface, unlike the undamaged paint surrounding it which gives a clearer reflection.

b) Autoglym's tests with strongly acidic, neutral and strongly alkali bird dropping substitutes highlighted negligible differences in the damage caused. However, differences in paint damage were noted when the substitute bird deposits had varying degrees of grain-to-liquid content. A grainier texture caused greater light distortion (dullness) when the paint moulded around it.

c) Wax and polish treatments – that protect against chemical attack from acid raid and UV sun damage, for example – provide limited protection from the paint moulding to bird droppings, although they will make them easier to remove. The longer the deposit remains on the bodywork, and the higher the temperatures, the harder the dried deposit will be, and the greater the propensity for the paint lacquer to mould to it as it cools. Bird dropping damage can only be prevented by motorists remaining vigilant and removing the deposit as soon as possible.

Autoglym's has outlined some tips for minimising the risk of damage from bird droppings:
- Remove the deposit at the earliest opportunity
- Motorists should use a moist cloth – Autoglym's Bird Dropping Wipes are ideal – to gently lift the deposit from the surface
- If the deposit is dry or doesn't lift easily, place a moist cloth over it for ten minutes to soften the deposit
- Dispose of any cloth or wipe used to remove bird droppings immediately and carefully wash your hands, as bird lime can harbour diseases

Paul Caller, CEO of Autoglym, said: "It's a great shame when an otherwise fabulous-looking car is blighted with a tell-tale patch of dull paint. As a result of this new research by our R&D team in Letchworth, we now understand why bird droppings are a frighteningly potent hazard to bodywork.

"As bird droppings become ever more prevalent through spring and into summer, motorists must be extremely vigilant to avoid permanent damage, especially those who park their cars under trees at home or at work. The only way to prevent the paint becoming noticeably tarnished is to carefully remove deposits as swiftly as possible."

This is my research on this subject

Bird Excrement
[: Uric acid , C5H4N4O3 [a diprotic acid , thus in strong alkali at high pH it forms the dually charged full urate ion, but at biological pH or in the presence of carbonic acid or carbonate ions it forms the singly charged hydrogen or acid urate ion as its pKa2 is greater than the pKa1 of carbonic acid][1]

One of the most serious threats to a paint surface; it's not only disgusting - it's a toxic hazard. Bird excrement contains unpleasant fungi, including Histoplasma capsulatum and Cryptococcus neoformans as well as bacteria, including Chlamydophila psittaci. Migratory birds, especially seagulls are known to spread hard-to-treat infections as they can carry antibiotic-resistant bacteria.
These are known to cause pneumonias as well as systemic infections. Various forms of encephalitis are also associated with bird droppings, so avoid direct skin contact.

Bird excrement is one of the most damaging environmental pollutants as they relate to automobile paint as it 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.

When you have an acid + moisture +oxygen + ozone all of which equates to a highly concentrated acidic solution, add heat (reactivity) to this equation, and you have the causes of pitting, a concave indentation on the paint surface. Heat and water act as a catalyst (reactivity); a vehicle paint surface temperature of >90.oF creates a very aggressive reactivity of the Alkaline, Uric Acid and Ammonia. This will cause surface etching, so they should be removed without delay. In this case, paint care not only serves aesthetics, but also helps preserve the vehicles. At lower temperatures (> 40.oF or less) there’s no reactivity and therefore little or no etching.

Acidic pollutant protection - the latest nanotechnology PPG CeramiClear™ Clear Coat or the newer nanotechnology products, although they are highly resistant to chemicals, detergents, scratches and ultra violet radiation (UV) will only offer limited resistance to acid etching. Organic or inorganic protective coatings, with the exception of Acrylic polymers, offer very limited resistance to acidic pollutants (acid rain, bird excrement, industrial fallout, hydrazine and etc).

An extract from “Environmental Pollutants” one in a series of in-depth technical articles that make up the i Art and Science of Detailing, TOGWT®

 

Good read.

 

So TOGWT I am a bit confused. It sounds like Autogym said that bird etching is not really etching but that the bird poo prohibits the clear coat to expand with the rest of the clear coat. Once the bird poo is removed the difference of surface levels remains causing a "dullness" to appear because of the light reflection.

Yet from the article bellow that it seems that bird etching is caused by the acid from the bird poo actually etching into the clear coat as what is commonly accepted as bird etching.

So... I'm confused to what is actually the cause of the "bird etching" from what you have posted. I believe both is possible explanations.

 

Cause - the different types of food ingested by birds affect the composition and quantity of droppings. Chemical aggression on the paint surface is caused by strong organic acids acting for an extended period and exposed to high temperatures.

Definition - the damage can range from paint discoloration to the film dissolving completely. Bubbling, swelling and etching are typical phenomena.

 

Gotcha good info to have.

 

Both Autoglym and TOGWT really know their s**t! [sorry...I could not help myself ]

EXCELLENT information, as always.