Paint Surface Problems / Correction

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Paint Film Surface Problems / Corections


Some methods described may be beyond the capabilities of the average detailer or enthusiast; in this case we strongly encourage the reader to consult a professional detailer or body shop concerning the matters discussed herein. The writer assumes no responsibility, expressed or implied, due to misuse or misinterpretation of the information or Methods used, or for any vehicle damage or injury that may occur due to the suggestions and information offered.


Paint Film Surface Problems:

* Acid / alkaline spotting (small concave circular marks) – (this is not actually a paint film ‘problem’ but is added here as many paint symptoms are incorrectly diagnosed as this) if an aggressive alkaline or acidic water solution alights on a paint surface and is subsequently dried by ultra violet radiation (UVR) it will produce a small concave circular mark, the so called ‘water spot’ (often with a white residue from the minerals)


Correction- an acetic acid (vinegar) will remove the spotting and an abrasive polish to level the paint surface may be necessary.


* Clear coat bubbles – so called solvent pop is caused by the paint topcoats trapping evaporating solvent gases during curing and drying (outgas) the pressure builds causing micro-explosions (pop) pushing up small blister in the wet paint or topcoat. Solvent pop will appear after the film is "skinned over" and when sanded will have pinholes

•Improper paint prep

•Wrong solvent or reducer

•Excessive film thickness

•Too heavy an undercoat can trap solvents •Insufficient outgas (paint cure)


Correction- Repaint the base coat and apply a clear-coat to the affected panel)


* Air entrapment - may have an appearance very similar to solvent pop or dust contamination small crater like openings in or on the paint film; cause - trapped air pockets in the wet paint film that rise to the surface and "burst" causing small fissures; lack of atomization is the cause of air entrapment and may be due to one or more of the following;

•Spray gun travel too slow or

•Spray gun held too close to painted surface,

•Low air pressure or

•Improper spray gun setup.


Correction- sand or compound with 1500 or finer grit paper to remove and then polish to restore gloss.


  • Dust contamination- will appear while the film is drying but, still "tacky". These concave depressions, under close examination, will have a speck of dirt in the centre of the crater


Correction- sand or compound with 1200 or finer grit paper to remove and then polish to restore gloss


* Paint cracks- acid rain, highly alkaline deposits, industrial fall or bird excrement will cause the clear coat to become opaque (cloudy) and / or etch (a small circular concave depression) another type of localized damage created by acidic substances are the results of water and high temperatures that will cause the polyurethane clear coat to expand, allowing the acid to breach the clear coat compromising the paints resin system, which is the binder that holds the clear together. The resultant cracks created will penetrate the clear coat, possibly down to the basecoat (colour).


Cannot be corrected by polishing or compounding, it requires refinishing by a body shop.


* Paint delamination - this is usually the result of the vehicle manufacturer's decision to produce vehicles with one of the following conditions;

•Insufficient clear coat film build

•Insufficient UV blockers in clear coat

•Surface primer was not applied over the e-coat (anti-corrosive primer)


The e-coat, (first layer of paint coating) is extremely susceptible to ultra violet rays, when ultra violet radiation (UVR) penetrates the clear coat and base coat; they are normally stopped by the surface primer.


E-coats oxidize (looks similar to chalk powder) very quickly when exposed to ultra violet radiation (UVR). Subsequently the base coat and clear coat no longer have a clean, firm surface to adhere to. Over time the base coat / clear coat detaches from the e-coat, resulting in this condition, which cannot be corrected by polishing or compounding


Correction- It requires repainting / refinishing by a body shop.


* Detachment- clear coat detachment is the result of inferior preparation of the base coat (colour) prior to the application of the clear coat. This may be evident on any area of a vehicle where there is trim such as mouldings door handles, window trim, etc. You need to remove the entire clear coat and re-apply a base coat and finally a clear coat. If you don't the new paint will separate due to delamination of the original clear coat under the new paint you applied.


Correction- repair requires correctly preparing the area by cleaning and sanding, the base coat must be examined (checked with a paint thickness meter) to insure correct film build and the clear re-applied. The entire panel should be refinished rather than attempting a ‘spot repair’. Any attempt to hide the defect by wet sanding and polishing / compounding will result in further damage by removing the paint build (thickness)


* Concave depressions in paint- refinishing using heat to outgas vs. air/time; auto body repair shops drying oven caused a ‘skin’ to form over the painted surface, trapping solvents in the paint. The vehicle was then subjected to rain water 48 hours after painting. The water is absorbed into the paint and implodes the top surface creating concave depressions in paints horizontal surfaces. Attempting to correct this by colour sanding and / or buffing will expose the uncured portion of the paint. It is extremely soft, and will not attain hardness for several months, if at all. Attempting to correct by these procedures before it is cured will result in an opaque paint finish (See also Acid / alkaline spotting)


* Orange Peel- orange peel is paint film surface that has a dimpled appearance that paint takes on due to an equipment/operator caused defect. Like wrong paint-gun pressure and/or distance from panel, an operator not knowing how to set-up the equipment for that particular type of paint, or even a partly blocked paint-gun nozzle, improper pre-paint preparation and /or paint application, or uneven drying of the clear coat.


It should be eliminated after the final shooting of clear coat by wet sanding the paint film surface, and polishing with a mildly abrasive polish and a high-speed rotary polisher.


Correction- it can also be removed (with limitations) by wet-sanding (colour sanding)


* Oxidation (chalk like appearance on the paint surface) - it starts as a chemical reaction that causes the resin binder system to overheat and dry out or it can also be caused by excessive (friction) heat generated during the machine polishing process (See also Compound Polishing Surface Temperature) leaving microscopic surface imperfections and micro fissures in the paint film surface that are vulnerable to deterioration. Once the air borne contaminates and pollution compromises the paint surface they accelerate the oxidation (reduction) or paint failure process.


Two stage paint system- (base, colour and isocyanate 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, which causes them to dry out or oxidize. The clear coat 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 (oxidize) the paint, causing it to fail.


Correction-

  • Two stage paint system- usually a repaint is required to replace the clear coat
  • Single stage paint system – oxidation can usually be removed by using detailers clay to remove any surface contaminants, and/or a solvent type chemical cleaner/polish (Zaino ZPC Fusion or Klasse All-In-One) and then a suitable abrasive polish (dependant upon how severe the problem) to remove the oxidized paint (Optimum Compound or Optimum Polish) with a cutting foam pad (LC orange or yellow, PC speed #4, or 1100RPM Rotary) and then apply a sealant and / or wax protection


  • Rust blooms- very small brown ‘pinholes’, they are usually caused by metallic brake dust that has penetrated the paint film surface and water / acid rain has produced rust.


Correction- sand or compound with 1200 or finer grit paper to remove and then polish to restore gloss. Consider using a decontamination product ValuGard's A-B-C system – Automotive International - Valugard Product Line


* ‘Soft’ (refinished paint) - this is usually due to not using the correct reducers / hardeners for the temperature the paint is to be sprayed and cured at, or the painter uses an incorrect mixture for a three part clear or there are contaminents on the paint surface

Correction-Use detailers clay and follow with a chemical paint cleaner


* Soft (Sticky) clear coat -

Cause- could be silicon contamination or a stong solvent 'softening' the paint film

Detailing - Use a chemical paint cleaner (PrepSol or Hi-Temp Silicone Remover) to remove silicone. Use a very soft foam (LC Black finishing pad) and a mildly aggressive polish as this type of ‘paint’ easily shows surface marring etc



Information resource-

  • PPG website on paint problems- Max Meyer Paint Defects - Select Defect Type
  • Information on paint - Car Refinishes North America -
  • Glasurit, Advice on Paint and Paintwork Defects - Glasurit
  • "Automotive Detailing Inside & Out, A Knowledge Base for the Perfectionist"– by Jon Miller
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