auto-paint-repair

Top 10 Auto Paint Repair Problems and Solutions

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Top 10 Auto Paint Repair Problems and Solutions

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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.

 

[highlight color=”eg. yellow, black”]Bleeding[/highlight]

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.

[highlight color=”eg. yellow, black”]Die Back[/highlight]

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.

[highlight color=”eg. yellow, black”]Dirt[/highlight]

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.
[highlight color=”eg. yellow, black”]Dry Spray[/highlight]
 
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.

[highlight color=”eg. yellow, black”]Fish Eyes[/highlight]

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.

[highlight color=”eg. yellow, black”]Orange Peel[/highlight]

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.

[highlight color=”eg. yellow, black”]Paint Color Matching[/highlight]

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.

[highlight color=”eg. yellow, black”]Paint Runs and Sags[/highlight]

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.

[highlight color=”eg. yellow, black”]Sand Scratches[/highlight]

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.

[highlight color=”eg. yellow, black”]Solvent Popping[/highlight]

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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Check out this video on Solvent Pop and Fisheye.

38 thoughts on “Top 10 Auto Paint Repair Problems and Solutions”

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    Reply

  3. 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

    Reply

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      Reply

    • 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.

      Reply

  6. I’m n the process of trying to finish some spots on a ’40 ford tudor that had been painted approx. a year ago. Bad orange peel! I color sanded and polished and it looks real good ,but a couple of spots went thru to primer. It’s black Nason2k single stage. I’ve been on the net trying to find out how to blend the new into the old-I keep getting a line around the repainted site. I’ve tried U-POL on the edges after painting and have gotten limited results. Am I maybe not blending(reducing the paint) and spraying a larger area and then applying the U-POL VERY FRUSTRATED!

    Reply

    • You need to sand the blend area with 2000 and try to blend the base, then I would clear coat the entire panel. It’s impossible to blend like how you want to do it with a single stage paint and get a somewhat quality job.. You must clear the entire panel. If you were doing base/clear, it would be easier to melt and buff into the old clear coat… Hope that helps

      Reply

  7. Hi my paint work is dropping back as though it is dry after bake then when i flat and polish my 2000 sand marks keep coming back after about 10 minutes could it be using to fast drying materials i dont no what else it could be would you have any idea thanks

    Reply

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    Reply

  9. I have a 1976 Ford F100 truck. The bed sides are good on it except someone put a bed cover across the top. I took the tabs off now I have little holes across the top on both sides. How do I keep the moisture out after I weld and grind the holes since I can’t get to the holes from the back side. So when I paint it won’t bubble the paint?

    Reply

  10. This was an excellent read…so very informative! You’ve explained all the details of painting a car in so much depth and with the appropriate steps that i am influenced to paint my 5-year old car myself. The DIYs are extremely helpful, thanks so much!!

    Reply

  13. It’s good that you mention that sand scratches are common car paint problems. I had my car painted a few weeks ago and noticed a sanding pattern near the taillights of my auto. It makes it look that the work hasn’t been finished yet. And this bothers me as I have spent money already to repaint the car. I will definitely look for another auto service that can take better care of my concern.

    Reply

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