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Top 10 Auto Paint Repair Problems and Solutions

Top 10 Auto Paint Repair Problems and Solutions

If auto painting is a new venture for you, it is imperative that you understand the basics of do it yourself auto body paint repair.

On this page you will find a treatment of the most common paint finish problems. This format details the condition of the problem, it’s causes, prevention and the best solution. We always heartily recommend anybody to spend an adequate amount of time preparing their vehicle’s surface for paint and therefore minimize the need for car paint repair afterwards. Too many times, enthusiastic rookie painters get ahead of themselves. They believe that a thick coat of paint will hide blemishes or flaws, it simply won’t.

Don’t rush into things. If you plan on spending a day or two just to prepare your car’s body surface for paint, the need for auto paint repair won’t be necessary.

Top 10 common paint problems:

  1. Bleeding  – Original finish discoloring or color seeping through the new topcoat color.
  2. Die Back – Loss of gloss after application.
  3. Dirt  – Small bumps deposited in, on, or under the paint film.
  4. Dry Spray – A rough, textured surface often confined to a small area.
  5. Fish Eyes – Tiny surface finish blemishes that resemble small circles of popped paint bubbles, of fish eye appearance.
  6. Orange Peel – Uneven Surface Formation – with an orange peel texture.
  7. Paint Color Matching - Finished panels that don’t match the color of standard panels.
  8. Paint Runs and Sags – Heavy application of sprayed material failing to adhere uniformly to the surface.
  9. Sand Scratches – Sanding pattern imperfections that show through the finished paint film.
  10. Solvent Popping – Blisters on the paint surface caused by trapped solvents in the topcoats or primer.

 

Bleeding

Condition: Original finish discoloring or color seeping through the new topcoat color.

  • Causes: Contamination  – usually in the form of soluble dyes or pigments on the older finish before it was repainted. (This is especially true with older shades of red).

Prevention:

  • Thoroughly clean areas to be painted before sanding, especially when applying lighter colors over darker colors.

Solution: Apply two medium coats of Bleeder or primer seal in accordance with label instructions. Then reapply color coat.

Die Back

Condition : Loss of gloss after application.

  • Cause : Improper evaporation of solvent or poor initial cure.

Suggested Corrective Action Checklist

  • Check if the imperfection is on the whole unit or in a specific area.
  • Check other units to determine if a pattern is beginning to take place.
  • Check for too fast a solvent selection.
  • Check for cool temperature during cure.
  • Check for lack of airflow during cure.
  • Check for improper film build up.
  • Check for improper flash times.
  • Check for incompatible products.

Dirt

Condition : Small bumps deposited in, on, or under the paint film.

  • Cause: Foreign particles entering the wet paint film.

Suggested Corrective Action Checklist

  • Check if the imperfection is on the whole unit or in a specific area.
  • Check other units to determine if a pattern is beginning to take place.
  • Check paint mixing/filtration process (was a strainer in place atop the paint cup when pouring in paint)
  • Check the spraying environment (booth, garage, workshop)
  • Check preparation process of unit, tacking, solvent wash, etc.
  • Check painter’s clothing.
  • Check the spraying equipment (was it thoroughly cleaned after previous use)
  • Check used paint filters for contamination.
  • Check for use of anti-static wipe or spray products.
Dry Spray

Condition : A rough, textured surface often confined to a small area.
  • Cause: Paint that lacks the ability to flow properly.

Suggested Corrective Action Checklist

  •  Check if the imperfection is on the whole unit or in a specific area.
  • Check other units to determine if a pattern is beginning to take place.
  • Check if the defect is specific to one color or many colors.
  • Check for a proper film build up.
  • Check for excessive film build up.
  • Check the distance of the spray gun from the surface when spraying. (You should always hold a paint gun at right angles to the surface being painted from a distance of 6-10 inches.)
  • Check reducing solvent selection and spray viscosity.

Fish Eyes

Condition : Tiny surface finish blemishes that resemble small circles of popped paint bubbles, which seem to occur almost as soon as paint hits an auto body surface.

  • Causes Improper Surface Cleaning Or Preparation.

Many waxes and polishes contain silicone, the most common cause of fish eyes. Small traces of silicone do not allow paint to settle evenly; rather they cause material to encircle the speck of silicone and form a fish’s eye. Silicone adheres firmly to the paint film and requires extra effort for its removal. Even small quantities in sanding dust, rags or from cars being polished nearby can cause this failure.- Check for possible contamination in paint materials.
– Check for painter contamination, skin oils, perspiration, greasy foods, etc.
– Check for any oils or contamination that might get into the spray area.
– Check for proper cleaning procedures prior to refinishing.
– Check airborne contamination in spray area.

  • Effects of the old finish or previous repair : Old finish or previous repair may contain excessive amounts of silicone from additives used during their application. Usually solvent wiping will not remove embedded silicone.
  • Contamination of air lines : Check for oil in air lines and spray equipment.
Prevention
  • Precautions should be taken to remove all traces of silicone by thoroughly cleaning with wax and grease remover. (The use of Fish Eye Eliminator is in no way a replacement for good surface preparation).
  • Add fish eye eliminator
  • Drain and clean air pressure regulator daily to remove trapped moisture and dirt. Air compressor tank should also be drained daily.

Solution : After affected coat has set up, apply another double coat of color containing the recommended amount of Fish Eye Eliminator. In severe cases, affected areas should be sanded down and refinished.

Orange Peel

Condition : Uneven Surface Formation – much like the physical appearance of orange peel. Results from poor coalescence of atomized paint droplets. Paint droplets dry out before they can flow out and level smoothly together.

  • Causes: Improper Gun Adjustment and Techniques

– Check for low air pressure.
– Check for wide fan spray patterns.
– Check the distance of the spray gun from the surface when spraying. You should always hold a paint gun at right angles to the surface being painted from a distance of 6-10 inches. Spraying at excessive gun distances causes droplets to become too dry during their travel time to the work surface and they remain as formed by gun nozzle.
– Check the spray gun was setup properly using the correct tips and spray cap.

  • Extreme Painting Environment Temperature

When the air temperature is too high, droplets lose more solvent and dry out before they can flow and level properly. The ideal temp to paint at is 22.5 degrees centigrade.

  • Improper Drying

Gun fanning before paint droplets have a chance to flow together will cause orange peel.

  • Improper flash or re-coat time between coats

If the first coats of enamel are allowed to become too dry, the solvent in the paint droplets of following coats will be absorbed into the first coat before proper flow is achieved.

  • Wrong and/or too little thinner or reducer

Under-diluted paint or paint thinner with fast evaporating solvents causes the atomized droplets to become too dry before reaching the surface.

  • Materials not uniformly mixed

Many finishes are formulated with components that aid coalescence. If these are not properly mixed, orange peel will result.

  • Alternatives

– Check the smoothness of the substrate surface.
– Check if the imperfection is specific to the one color.

Prevention

  • Use proper gun adjustments, techniques and air pressure.
  • Schedule painting to avoid temperature and humidity extremes. Select the thinner or reducer that is suitable for existing conditions. (The use of a slower evaporating solvent will overcome this.)
  • Always allow sufficient flash and dry times. Never dry by fanning.
  • Always allow proper drying time for undercoats and topcoats. (Not too long or too short.)
  • Select the thinner or reducer that is most suitable for existing environmental conditions to provide good flow and leveling of topcoat.
  • Reduce to recommended viscosity with proper thinner/reducer.
  • Stir all pigmented undercoats and topcoats thoroughly.

Solution : Compounding may help with removing orange peel from paint – a mild polishing compound for enamel, rubbing compound for lacquer. In extreme cases, sand down to a smooth surface and refinish, using a slower evaporating solvent at the correct air pressure.

Paint Color Matching

Condition : Finished panels that don’t match the color of standard panels.

  • Causes : Variations in application and/or paint materials.

Suggested Corrective Action Checklist

  • Check other units to determine if a pattern is beginning to take place.
  • Check for complete hiding.
  • Check for variables in spray application.
  • Check lines and equipment for leftover contamination from previous color.
  • Check for improper mixing.
  • Check for proper agitation.
  • Check gun pattern.
  • Check the distance of the spray gun from the surface when spraying. (You should always hold a paint gun at right angles to the surface being painted from a distance of 6-10 inches.)
  • Check that you setup the equipment correctly.

Paint Runs and Sags

Condition : Heavy application of sprayed material that fails to adhere uniformly to the surface.

  • Causes: Too much thinner or reducer:
  • Check for excessive fluid delivery.
  • Wrong thinner or reducer

– Check the solvent selection is correct (not too slow).
– Check to see if the paint was reduced correctly.

  • Excessive film thickness without allowing proper dry time

– Check for excessive film build up.
– Check for too short flash (dry) time.
– Check for excessive application overlap.

  • Low air pressure (causing lack of atomization), holding gun too close or making too slow a gun pass

– Check the distance of the spray gun from the surface when spraying. (You should always hold a paint gun at right angles to the surface being painted from a distance of 6-10 inches.)
– Check for insufficient air pressure.

  •  Painting environment or surface too cold

– Check for low spray area temperature.
– Check temperature of unit.
– Check temperature of paint.

Prevention

  • Read and carefully follow label instructions. Select the thinner or reducer that is suitable for existing shop conditions.
  • Select proper thinner/reducer.
  • Don’t pile on finishes. Allow sufficient flash and dry time in between coats.
  • Use proper gun adjustment, techniques and air pressure.
  • Allow vehicle surface to warm up to at least room temperature before attempting to refinish. Try to maintain an appropriate painting area temperature for paint areas.

Solution : Wash off the affected area and let dry until you can sand affected area to a smooth surface and refinish.

Sand Scratches

Condition : Objectionable sanding pattern imperfections that show through the finished paint film.

  • Cause : Imperfections due to soft primer, improper sanding techniques and low top coat film build. Excessive film builds with improper flash times.

Suggested Corrective Action Checklist

  • Check if the imperfection is on the whole unit or in a specific area.
  • Check other units to determine if a pattern is beginning to take place.
  • Check if defect is specific to one or many colors.
  • Check for correct sandpaper grit (too coarse).
  • Check topcoat film thickness.
  • Check for proper feathered edge technique.
  • Check for uncured primer.
  • Check for poor quality solvent used in undercoats.
  • Check for proper flash and dry times.
  • Check for excessive primer film builds.
  • Check for proper paint spray gun technique and atomization.
  • Check for under reduced primer (bridging scratches).
  • Check for sanding before primer is cured.
  • Check for film builds of sealer or no sealer.

Solvent Popping

Condition : Blisters on the paint surface caused by trapped solvents in the topcoats or primer – a situation which is further aggravated by force drying or uneven heating.

  • Cause: Improper surface cleaning or preparation

– Check other units to determine if a pattern is beginning to take place.
– Check if the imperfection is on the whole unit or in a specific area.
– Check if defect is specific to one or many colors.
– Check if defect is most prevalent on horizontal surfaces.

  • Wrong thinner or reducer

– Use of fast-dry thinner or reducer, especially when the material is sprayed too dry or at excessive pressure, can cause solvent popping by trapping air in the film.
– Check for correct reducing solvent.

  • Excessive film thickness

– Insufficient drying time between coats and too heavy application of the undercoats may trap solvents causing popping of the color coat as they later escape.
– Check for excessive film build up.
– Check for high fluid delivery.
– Check for high viscosity.
– Check for too much overlapping in film build.
– Check for proper flash and purge times.

Alternatives

– Check for high temperature in first part of force dry.
– Check for low air pressure.

Prevention

  • Thoroughly clean areas to be painted.
  • Select the thinner or reducer most suitable for existing painting area conditions.
  • Don’t pile on undercoats or topcoats. Allow sufficient flash and dry time. Allow proper drying time for undercoats and topcoats. Allow each coat of primer to flash naturally – do not fan.

Solution : For refinishing solvent popping, if damage is extensive and severe, paint must be removed down to undercoat or metal, depending on depth of blisters; then refinish. In less severe cases, sand out, re-surface and re-apply topcoat.

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8 Responses to Top 10 Auto Paint Repair Problems and Solutions

  1. Jaime Martinez November 18, 2012 at 12:47 am #

    Hi Tony
    Very helpful tips to approach the most frequent issues on automobile paint repair.

  2. VALMA November 18, 2012 at 11:19 am #

    YEA!!! I ALWAYS ENJOY READING AND WATCHING YOUR VIDEO’S . I HAVE LEARN ALLOT FROM YOUR COURSE. AM LOOKING FORWARD TO GET MY PROJECT GOING JUST WAITING TO GET SOME MORE STUFF TO START. THANKS FOR THE KNOWLEDGE I HAVE SO FAR I WILL PROUDLY MAKE GOOD USED OF IT. SO FAR THIS IS THE BEST ONLINE PROGRAM EVERYTHING IS EXPLAIN IN DETAILS.
    THANKS AGAIN MY BROTHER

    • Tony November 18, 2012 at 7:27 pm #

      Awesome Valma! Thanks for the kind words. Send us updates once you start rocking on your project ok :)

  3. John Wafford November 18, 2012 at 7:46 pm #

    I would love to take advantage of your VIP Training, but at my age (67) spraying is no more than a profitable hobby that doesn’t justify the cost of your training. However, your tips have come in very useful

    • Tony November 18, 2012 at 7:50 pm #

      Thanks John. We have members your age and older who love the community. It’s more than just training. It’s community support and more. What price range are your considering for investing in your education? Stay tuned. We sometimes do special promos for the VIP club and community.

  4. John Wafford November 18, 2012 at 8:39 pm #

    Thanks for your reply Tony. I’ll keep an eye out for your special promos.

  5. Graeme April 11, 2013 at 4:10 am #

    Is there a way of preventing cracks in seam on motorhome ?? Tried seam sealer. next option is mig welding or fitting something over both panels..
    http://i4.photobucket.com/albums/y146/EBXR8240/Buspaintcracks001_zpsbeec78ca.jpg

    • Tony April 13, 2013 at 10:57 am #

      hi! You mentioned mig welding, that would be a great idea. Then you would grind it flat, then apply some 2 part epoxy over it to fill. Then you would be able to prime and paint it with a top coat of your choice.

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