Tech / Tech Articles

7 Common Paint Mistakes—and How to Avoid (or Fix) Them!

Some people have no qualms about tearing into an engine.

Others can practically rebuild a transmission in their sleep.

Yet, many of these same people are intimidated by doing their own paint job. Maybe it’s the thought of doing inadequate prep work…the fear of mixing the materials improperly…or just the lack of patience to put in the necessary time. Most likely, though, people just get scared off by bad paint.

Orange peel, wrinkling, paint curtains—these are all conditions that can ruin an automotive paint job. The good news is they’re all avoidable and fixable. In conjunction with the experts at Kirker Automotive Finishes, we’ve put together a list of some of the most common paint mishaps and how to avoid them. We’ve also included some basic information on how to fix these conditions.

Bad paint doesn’t have to be permanent. And neither does your fear of painting your own hot rod or truck. Find out how to avoid (and fix, if necessary) these seven common paint maladies and tackle your next paint job at home.

Cracking

30134d1344723975-paint-cracks-cracks

(image courtesy of bimmerwerkz.com)

Also known as wrinkling, splitting, or checking, cracking can include cracks of random size and often resembles the wrinkles on a reptile’s skin.

COMMON CAUSES

  • Insufficient surface preparation: Step one in avoiding cracks or many other imperfections is properly preparing the substrate for paint. Cracking or other imperfections in the surface itself should be removed before the new material is applied.
  • Lifting of substrate: When the wrong reducer is used in a top coat, or when certain materials are top coated before achieving full cure, the undercoat may lift in a way that appears like cracking.
  • Improper choice in reducer or hardener: Be sure to follow the paint manufacturer’s suggestions on the type of reducers and hardeners to use with each paint. Improper or low quality materials may have an adverse effect on the finished dry paint film.
  • Incorrect mixing ratio: If too much activator/hardener is used, or if the correct ratio is not properly mixed, defects may appear in the finished dried paint film.
  • Environmental conditions: Excessive heat or humidity during application and curing can cause surface imperfections such as cracking.
  • Too much, too quickly: Spraying too much material in full wet coats can lead to cracking.

HOW TO FIX IT
You’ll need to allow the paint film to cure completely. Once cured, you can sand out any imperfections and reapply the paint. Avoid the same mistakes by keeping the common causes above in mind.

Orange Peel

auto_paint_orange_peel_lg

(courtesy of dsmtuners.com)

This is one of the most common conditions we hear mentioned when people talk about painting their own vehicle. As the name suggests, orange peel is a condition in which the dried paint has an appearance or finish similar to an orange peel.

COMMON CAUSES

  • Excessive film thickness: Again, applying too much material in full wet coats can cause issues. This includes preventing the paint from flowing to an even film before drying.
  • Improper use of reducer: The wrong reducer for the conditions can cause solvents to evaporate too fast, allowing the paint film to dry before the material has properly flowed out to the desired appearance. Make sure to use the right reducer for the temperature and conditions in which you are working.
  • Gun troubles: Make sure to use the correct spray gun, fluid tip, and air cap for your application. Also, insufficient air pressure at the tip of the gun can prevent paint material from properly atomizing, keeping it from flowing out to a desired appearance.
  • Poor technique: Any number of factors, including the position of the gun tip, the speed of the pass, the degree of overlap between passes, and the distance of the gun from the panel, can lead to orange peel.

HOW TO FIX IT
If orange peel is minimal, sand out the texture in the dried paint film with a fine grit sandpaper, then compound and polish to restore gloss. If orange peel is significant, sand out imperfections and reapply paint using properly reduced material, air pressure, and technique. Making adjustments to the gun settings may also help.

Runs and Sags

TS-PDSG_runs

(image courtesy of consumerreportscdn.org).

Whether on the side of a vehicle or while repainting a kitchen or bathroom, we’ve all probably dealt with paint sags or runs at some point. When struggling with runs, sags, or curtains on an automobile, there are some likely culprits.

COMMON CAUSES

  • Improper reducer/too much reducer: Again, your choice in reducer and hardener plays a key role in your final finish. Be sure to choose the appropriate reducer for the type of material being sprayed, and the shop conditions in which they will be sprayed. Reducer that evaporates too slow and excessive use of reducer are two primary causes of runs and sags.
  • Excessive film thickness: Too much material in full wet coats leads to excess paint that runs.
  • Insufficient flash time: Not allowing enough time for solvent to flash off of the first coat before applying next coat can also cause runs.
  • Inadequate air pressure: Paint sags can result from insufficient air pressure at the tip of your paint gun. It’s also important to use the correct fluid tip and air cap, and the proper paint gun for specific materials.
  • Poor technique: Runs and sags can be caused by improper gun tip position, the speed of the pass, the degree of overlap between passes, and the distance of the gun from the panel.

HOW TO FIX IT
If the paint is wet: Remove with solvent, clean the area, and reapply coating.

If the paint is dry: Sand out any runs and reapply coating.

Fish Eyes

fish_eye_defect_in_composites

(image courtesy of chemtrend.com)

Appearing as small, circular craters spread throughout the paint film, fish eyes are a common enough problem that you can find specialized Fish Eye Eliminator.

COMMON CAUSES
Fish eyes typically (but not always) appear in a paint surface soon after application. There is one reason for the appearance of fish eyes: contamination.

Contamination found on the substrate (oil, water, grease, wax, etc.) is the main cause of fish eyes. Contamination that occurs during the application and/or prep process is the other common cause. This can occur when water and oil enter the air stream due to the absence of a water and oil separator, or the reuse of shop rags, which may have previously been used with silicone or other materials. Paints are extremely susceptible to certain waxes and silicone products, so care should be taken whenever car care products are used in the general vicinity of a paint shop.

HOW TO FIX IT
If the paint is wet: Remove with solvent, properly prepare the surface, and reapply paint material.

If the paint is dry: Sand out fish eyes, and then reapply paint material. Add a fish eye eliminator to the paint before reapplying. The surface should always be completely clean and dry before applying paint materials.

Flaking and Peeling

How-to-Prevent-Car-Clear-Coat-Peeling-5-Ways-to-Do-It

(image courtesy of detailxperts.net)

It’s generally a bad sign when pieces of dried paint peel or flake off of your vehicle. If you’re experiencing this condition, delamination has occurred. The dried paint film is no longer adhering to the substrate, causing it to pull away in strips or flakes. Here’s how to avoid or fix that problem.

COMMON CAUSES

  • Improper surface preparation: If the substrate is not properly abraded, or features surface irregularities and/or rust spots that are not addressed prior to the application of paint, delamination may occur (sometimes immediately, other times after a lengthy period). Remember, your vehicle’s finish is only as good as what lies beneath it.
  • Insufficient film thickness: Consistent and adequate film thickness is important. Paint that has been applied too thinly has an eventual tendency to pull away from the substrate.
  • Failure to follow application instructions: Adhesion may become an issue if specific application instructions are not followed. For example, certain undercoats that have fully cured must be sanded before taking a topcoat to avoid delamination.

HOW TO FIX IT
If the area in question is relatively small, remove flaking and peeling paint, and then reapply paint material as you would during a spot repair. For larger problem areas, sand the entire paint surface and reapply paint material. Take care to follow application instructions and build the material to a sufficient film thickness.

Absence of Gloss

A matte finish is nice if it’s what you really want. But if you’re expecting a nice gloss finish and you get a more satin or matte look—well, that’s bad. If your automotive paint isn’t giving you the gloss finish you want, there are a few possible causes. Keep in mind, though, that all paints will lose some degree of gloss over time due to everyday weathering.

COMMON CAUSES

  • Insufficient film thickness: If the final coat of single-stage paint or a clearcoat is applied too thinly, finished paint film will not exhibit full gloss potential. This also may occur when material is applied too dry, causing orange peel.
  • Insufficient flash time between coats: If solvent does not have adequate time to flash between coats, the result may be a loss of gloss in finished paint film.
  • Excessive film thickness: A repeat suspect in multiple paint problems, excessive film thickness can prevent the finished paint film from achieving full gloss. Make sure to not apply too many full wet coats of paint.
  • Wrong reducer: The wrong grade or temperature reducer for the conditions can cause solvents to evaporate too fast. This will allow the paint film to dry too quickly, leaving a satin or matte finish. This can also occur if too much solvent is used.
  • Insufficient time between different materials: Gloss may be compromised if a topcoat or clearcoat is applied too soon, or in some cases, before the previously applied material has achieved a full cure.
  • Poor cross ventilation: It is important to maintain air movement even after application. Failure to do so can impede the overall gloss development.

HOW TO FIX IT
Once paint film is cured, compound and polish to restore gloss or scuff sand and reapply paint.

Poor Hiding

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Uneven filler or substrate color can cause poor hiding. (image courtesy of corvetteforums.com)

Is your dried paint allowing the substrate to show through?

While paints are designed for opacity, poor hiding can allow variances in the vehicle surface or previously applied coating material to be visible through the finished paint. Here are some typical causes:

COMMON CAUSES

  • Too much reducer: Reducers are totally transparent, so using too much reducer takes away from the normal hiding level of the paint.
  • Wrong primer color: Certain color primers are more difficult to cover, depending on the color of the paint. For instance, a white paint will cover a light-colored primer faster than a black or dark gray.
  • Uneven color on substrate: Body fillers and other variations in substrate color can cause an uneven appearance.
  • Insufficient coats: Depending on the paint color used, a manufacturer’s suggestion may not be enough to achieve proper hiding and additional coats should be applied.
  • Improper paint prep: Paint must be sufficiently agitated prior to use so that pigments can be mixed throughout the material. This is especially true with older materials, because pigments may easily settle to the bottom of a container if left untouched for long periods.

HOW TO FIX IT
Simply continue to apply properly agitated and reduced material until desired hiding level is achieved.

For more valuable paint help, including troubleshooting advice for other paint conditions, check out the Kirker Automotive Finishes website.

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15 Comments

  1. Thank you do much for the tips and advice you share with us do it your selfers. I’m planning on a complete make over on my dirt circle track car next year. I’m stripping black , green and what ever other colors beneath. Going back with the summit racing red on the body and doing white on chassis and interior. White because it shows cracks and other defects really well. Can’t wait hardly for off season, not.

  2. I’ve had luck in wet sanding an existing paint job in a small spot, and reapplying clear coat. All with rattle can. I’ve had good results. Tonight I had to attempt to put a bit of color on an area. I had such good results in wet sanding and reapplying a clear coat, that I figured I was up to spray a little primer on and color, then clearcoat. No fuss. Primer went on fine, but to my horror, the blue base coat immediately pock-marked, leaving large circles with primer showing through. I’m hoping a 2nd coat will at least get everything a uniform color, even if it’s the surface of the moon.

    Couple theories, Did I mix two different types of primer/base coat. Such as enamal and laquer Going to check the labels after I finish this posst. Or.did I put the color coat on the primer too soon? I gave it about a half hour. Anyway, ugh, it’s just a spot job, but I think it’s going to look worse than the scratch I filled.

    Wish me luck.

  3. This definetly solved my paint job issues ! . Thanks so much !

  4. Can I go back, at a later date, and apply any additional clear, if I do not get the gloss I desire? (Referring to the next week or so)

    Thank you

    • OnAllCylinders Staff says:

      For a 2-stage paint system? Though every paint manufacturer’s system may be different, the short answer is probably no. An important part of the process is the adhesion that occurs between the clear coat and the base coat during the initial drying process.
      In essence, the 2 layers bond to each other during that step, promoting better adhesion.
      Now, that’s not to say you can’t touch-up clear coat later, but it’s probably not wise to add an additional full coat of clear outside the manufacturer’s recommended time window for the initial application.
      Make sense?

  5. Lyle Thomsen says:

    I found that whenever the basecoat or single stage paints tend to leave fisheyes, I add a few drops of 30 weight oil to the paint mix and re agitate the paint,then respray. No more fisheyes!

    • Sparky Lyle says:

      Nice, Lyle. Exactly the kind of helpful commentary I’ve grown to expect from any ‘given’ Lyle.

    • Thank you for that information on feesheyes, I had a ton of them in some Rustoleum I sprayed yesterday, I wet sanded and didn’t have any 30wt so I tried about three drops of my 20-50wt Harley Synthetic Oil in today’s paint and it covered what was there and layed down great.

  6. John Mallia says:

    Rubbed clear right d oh wn to feather edge. After applying undercoat and paint came nice. After buffing a circle broke out and turned whitish. Please explain.

  7. Andries vd walt says:

    Hi I want to know if I used 2k gray primer without any hardener and then apply the basecout will there be any problems waiting for me in the future or not
    Thnk you

  8. Can fast hardener be applied on wall oil paint

  9. My malibu was recently painted and the coveei g was fine but there are dull spots 8j n the paint glossy in other spots but dull in some, like a dry dust. It’s an acrylic enamel and I tried washing and waxing it but still the same results just not as worst how can i fix this problem

  10. Recently i had given my Royal Enfield bike parts for painting matte black . Got done in 1 day but the paint was not glossy as showroom finish. It was like flat matte paint on the wall.
    Wen i asked the painter he said he mixed 90% matte clear so its best like that.
    But i refuse to accept him bcz i need showroom glossy matte finish.
    What went worng ??

  11. Jaime Arias says:

    Hello I have a question I painted my fender with base coat.but I noticed that I could see the scratches on it from when I had sanded it the base coat it’s a metallic paint but I haven’t sprayed clear on it yet what could I do to fix the scratches before I put clear on it or I’m I screwed..if you could help I’ll appreciated thank you

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