Paintwork Defects and Damage

Diagnosis and Damage Assessment

Paint concerns, regardless of their causes, are part of the everyday work in the paint shop. Correct damage assessment and determination of the cause are preconditions for a professional resolution of a paint concern.

Paint concerns can still occur through a variety of causes, despite improved paint materials and new spray methods.

NOTE: A first appraisal of the paint damage should be done after washing the vehicle and before chemical cleaning. External factors such as rust, droppings, incorrect or insufficient paint care can then be more easily detected.

Diagnosis is best done in daylight but not in direct sunlight. Exact evaluation can also be done under artificial light daylight corrected lamps.

Paint Damage Guide

The most important paint damage concerns which make a paint repair necessary are:

• Damage from biological paint contamination such as bird or insect droppings and tree resin.
• Environmental paint damage caused by acid rain.
• Metal particles embedded in the paint surface caused from rail dust during vehicle transportation or factory emissions fallout.
• Chemical paint damage caused by industrial contaminants such as smoke, fuel, acids, oils.
• Mechanical damage caused by stone impact during operation, scratches in the car wash and parking.
• Damage caused by faults in treatment. Application defects such as paint runs or orange peel.
• Dirt inclusions in the paint layer, e.g. caused by dust in top coat or textile lint.
• Damage due to corrosion.

Before repair of such paint concerns, exact diagnosis must be performed to determine the cause exactly. On the spot diagnoses using simple aids and processes are often enough.

Diagnosis without disturbing the paint is done by:

• Feel with a flat hand for embedded particles.
• Optical inspection without visual aids, under suitable light conditions from a suitable angle and correct distance.
• Optical inspection with the help of a magnifying glass.
• Measurement of the film thickness using magnetic coating thickness meters for steel panels.
• Electronic measurement of the film thickness on steel and aluminum panels as well as plastic components.

A preliminary test method is the finger nail test. With suitable experience the existing hardness of the paint can be determined.

Test methods where the paint is partially destroyed are:

• Adhesion test using adhesive tape.
• Lattice cut test process to check the strength of adhesion.

Under certain circumstances these test methods are not enough for a certain diagnosis. In this case, paint diagnosis under controlled conditions must be performed.

Measuring and testing equipment for painted surfaces

• Coating thickness measuring devices
• Magnifying glass
• Suitable photographic equipment with macro lens

Paint Damage Caused by Environmental Factors

In all the cases of paint damage described below, if the damage is irreversible a new paint finish must be applied.

• Bird droppings
• Insects
• Tree resin and sap
• Tar spots
• Rust film/deposits from industrial fallout
• Battery acid
• Brake fluid

Paint Damage Caused by Bird Droppings

Bird dropping damage appears most often as matt, etched topcoat areas of various sizes. If left on the vehicle for a long time, crack formation and etching into the substrates can occur.

Cause/damage pattern:

• Bird droppings are particularly harmful in combination with heat and moisture. The urea (white part) has a very high salt content and is very aggressive.
• The intensity of the damage varies depending on the type, quantity, contact time and extent.
• Cracks, etching, marks up to dissolution of the top coat are the results.

Repair of damage:

• If the damage is light, perform a polishing repair.

Paint Damage Caused by Insects

At insect impact locations on the hood, roof and bumper, small etched or etched through paint marks with partially visible spots of filler.

Cause/damage pattern:

• The top coat layer is destroyed in a short time by surface swelling and etching.
• Colliding insects stick to the paint surface. In combination with moisture and heat, because of the resulting acids the insect bodies sink into the paint top coat.
• The corrosion is usually only a few millimeters thick.

Repair of damage:

• Wash the vehicle, treat the affected area with insect remover. Clean the paint surface several times.
• Protect with hard wax.
• If washing the vehicle does not correct the damage, perform a polishing repair.

Paint Damage Caused by Tree Resin or Sap

Small yellow-brown marks or drops on the horizontal parts of the vehicle. The drops melt in sunlight. Resin damage only occurs in the warm summer months.

Cause/damage pattern:

• Because of their chemical composition, tree resins combine with or adhere very well to paint top coats and cause them to swell. The higher the temperature, the more intensive is the chemical bonding between the resin and the paint topcoat surface.

Repair of damage:

• Use a bug and tar remover following manufacturers recommendations.
• Final clean with a wax and grease remover.
• If chemical cleaning does not correct the damage, perform a polishing repair.

Paint Damage Caused by Tar Spots

Yellow or dark marks.

Cause/damage pattern:

• Firmly stuck spots of tar which lead to discoloration of the surface. In some cases penetration through the clear-coat into the top coat.

Repair of damage:

• Clean the paint surface with tar remover following manufacturers recommendations and polish.

Rust Film/Deposits from Industrial Fallout

Small round marks, about 1 mm in size, in all shades from black, grey, blue to reddish, on the horizontal surfaces of the vehicle.

Cause/damage pattern:

• Deposits from oil fired systems and industrial plant, especially at high humidities and inversion weather conditions, cause damage to the paint top coat.
• As the activity time increases so called rust halos form. They spread as long as the deposits corrode.
• Industrial fallout containing iron will no longer be removable after a few days!

Repair of damage:

• 
  For additional information, refer to: Paintwork Defects and Damage (501-36 Paint - General Information, General Procedures).
  

Damage Caused by Battery Acid

Splashes of battery acid caused by incorrect handling of wet-cell batteries.

NOTICE: Batteries contain sulfuric acid. When working near the battery, or where there is battery acid on the vehicle body, protect the skin and eyes from contact with the acid. If battery acid contacts the skin or enters the eyes, flush the affected area immediately with water (flush for at least 15 minutes) and call a doctor without delay. If acid is swallowed, call a doctor immediately. Failure to follow these instructions may result in personal injury.

Cause/damage pattern:

• •Etching of the paint layer to decomposition of the paint finish

Repair of damage:

• Immediately flush the acid splashes with plenty of water and neutralize with car washing liquid.
• If the contact time of the acid was short, perform a polishing repair.

Paint Damage Caused by Brake Fluid

Careless handling of brake fluid. The glycols contained in the fluid cause swelling and discoloring.

Cause/damage pattern:

• The temperature and contact time are critical. Splashes lead to loss of shine and lightening of color.

Repair of damage:

• Immediately remove fluid from painted surfaces.
• Follow with application of a wax and grease remover following manufacturers recommendations.

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