Paint Disasters

Jan. 1, 2020
They're maddening, frustrating and costly. But you can avoid most of them by sticking to the proper procedures.
Paint Shop - November 2000Paint DisastersThey're maddening, frustrating and costly. But you can avoid most of them by sticking to the proper procedures.Diesel exhaust, erratic sprinkler systems, the occasional can of WD-40 or Armor All. Paint shop nemeses are many, varied and often maddeningly hard to pinpoint. And nearly everyone who has paid their spray booth dues has a horror story to tell.Take Art Allred. Today he's training director for Valspar, but seven years ago he was working as a jobber salesman when he received a call from a customer who had just painted a Corvette and a Chevrolet Blazer. "He asked me to come over because he put the vehicles outside in the sun, and both of them popped and blistered," Allred recalls.When Allred arrived, the refinisher said he had used an epoxy primer-sealer on both jobs. The product was somewhat transparent, and the lighting in the booth was less than ideal, so the painter continued piling on coats until he achieved what he perceived to be proper coverage. "He told me he put on six to eight coats," Allred says. "The label directions recommended two. He kept laying it on because he thought he saw Bondo and other surface marks showing through. But what he saw were shadows caused by bad booth lighting."COMMON PAINT
PROBLEMS
Sandscratch Swelling 
(the paint solvent soaks into sand scratches in the underlying paint and causes them to swell)
Probable Causes: Improper surface cleaning or preparation, improper thinner or reducer, too little reducing or wrong thinner in primer-surfacer causes bridging of scratches, primer not dried properly, too heavy undercoat application, application of color when the original finish is too sensitive to the paint solvents used, too heavy an application of color or lack of flash times between coats.
Remedy: Sand the affected area down to a smooth surface and apply the appropriate sealer before refinishing.
Solvent Popping 
(surface blisters caused by trapped solvents in the top coats or primer- surfacer)
Probable Causes: Improper surface cleaning or preparation, wrong thinner or reducer, excessive film thickness, infrared facilities too close, air pressure that is too low or too high, insufficient flash time before force drying, baking temperature too high.Remedy: If damage is extensive and severe, the paint must be removed to the undercoat or metal. The damaged areas must then be refinished. In less severe cases, the damage can be sanded out, resurfaced and then re-top coated.Runs or SagsProbable Causes: Too much application, solvent too slow for conditions, too much thinner or reducer, incorrect spray booth lighting, incorrect painter technique, surface contamination, shop too cold or surface too cold, low air pressure, paint drops from the gun, improper equipment setup.Remedy: Wash off the affected area and let it dry until it can be sanded to a smooth surface. Then refinish. Polishing is recommended for solid colors and clear coats. When working with base coats, refinishing is necessary after sanding.CorrosionProbable Causes: Metal surface contamination, paint removed by chipping or scratches, inadequate surface pre-treatment, rust was not completely removed before refinishing or the paint film was destroyed because of contamination.Remedy: Remove the coating to the substrate, thoroughly clean the vehicle and then apply an etching primer, the primer-surfacer, sealer (optional) and the top coat.Cracking 
(splitting of the paint film)
Probable Causes: Excessive film thickness, materials not uniformly mixed, insufficient flash off time, incorrect additive use, vehicle surface temperature too hot or too cold, use of incompatible products, omitting the activator when using a 2K product and painting over a previous cracked finish.Remedy: Remove the cracked area, apply the proper undercoat or sealer and apply the top coat.Featheredge Splitting
(stretchmarks along the featheredge) Probable Cause: Applying the undercoat in heavy, wet coats and trapping the solvent, materials are not uniformly mixed, using the wrong thinner or reducer, improper surface preparation, improper drying, or excessive use and film build of putty.
Remedy: Remove the finish in the affected areas and refinish.Fish Eyes
Probable Causes: Surface contamination.Remedy: Stop painting if fish eyes appear while refinishing the vehicle. Decide if you should continue painting. If it's an isolated area, let the area flash and then dry spray. If there are major problems, let the vehicle dry overnight. Then determine the cause of the problem and then repaint the area.Lifting 
(the ability of a coatings solvent to partially expand an underlying coating, which results in a rough finish)
Probable Causes: Uncured or lacquer substrate, using aggressive solvents in the coating, applying the coat heavily, insufficient flash time and improper featheredging.Remedy: Remove the uncured material, featheredge the lifted area, reprime using faster solvents, apply lighter coats with long flash times, apply a quality sealer coat and then repaint.Orange Peel
Probable Causes: Improper gun adjustment techniques, extreme shop temperatures, improper drying, improper flash time or recoat time between coats, wrong or too little thinner or reducer, materials not uniformly mixed, sealer applied with texture, substrate not prepared smoothly.
Remedy: Flat sand and compound, sand the surface smooth and then reapply the top coat.Pinholing
(tiny holes in the paint, which may have raised edges, that penetrate to the underlying surface)
Probable Causes: Improper surface cleaning or preparation, contamination of air lines, wrong gun adjustment or painting technique, wrong thinner or reducer, improper drying, excessive film application, insufficient flash time before force drying.Remedy: Remove the film in the problem areas, seal if you choose to and then refinish.ScratchesProbable Cause: Frequent use of automatic car washes.Remedy: Machine buff using a quality product without silicone. In severe cases, sand and repaint.ChippingProbable Causes: Travel on highways or gravel roads, use of a non-activated sealer/ undercoat system, unsealed lacquer primer-surfacer, too much or too little film build, improper amount or quality of activator or overbaking.Remedy: Use activated products, use quality activators and solvents, and ensure proper film builds.Acid Rain 
(discolored spots in the top coat pigment, a loss in the transparency or gloss of the clear coat and etching marks)
Probable Cause: Rain containing effluents from manufacturing, chemical industries and power stations.Remedy: Wash the vehicle with detergent and water, and then rub the affected area with rubbing compound and polish. In severe cases, you may have to sand it to prime and refinish the area.Bird Droppings 
(etching marks in the top coat. Discolored spots will show in the paint pigments)Probable Cause: Contamination from agricultural and horticultural sprays.Remedy: Using a brush and a lot of water, wash the vehicle with detergent. Then rub the affected areas with rubbing compound and polish. In severe cases, you may need to sand away the craters.BlisteringProbable Causes: Finish subjected to high moisture for an extended period of time, the vehicle was covered with plastic and stored for a long period of time, severe moisture in the air supply during primer or top coat application, or the vehicle not being dried properly before painting and after water sanding.Remedy: Remove the finish and then inspect for moisture damage, such as rust. Apply a sealant and then the top coat.Allred took a razor blade and cut along the edge of one of the huge blisters on the Corvette. As he sliced through the layers of clear coat, color and primer-sealer-right down to the fiberglass-he remembers actually smelling the solvent fumes that escaped. "You could roll a sheet of paint off that car just like it was wallpaper. In fact, I kept a roll of it for years. We sent a sample to the manufacturer, and they told us there were 12 to 13 mils of primer sealer alone on there."The moral of the story: "Follow label directions and make sure your booth is well lit," Allred says.Infectious Fish Eyes
Of all paint disasters, fish eyes are perhaps the most insidious and catastrophic. Once loosed, they're like a plague that can infect every job in the shop. They're caused by silicon, often from such sources as oil, grease, wax, and the aforementioned WD-40 and Armor All. But who would suspect diesel exhaust? Certainly not the former shop owner who tells this story: "We had just finished a truck, and when we started it up to move it out of the shop, it spewed diesel fuel out the exhaust. We got tons-and I mean tons-of fish eyes on every car in the shop-six or seven jobs. They were so bad it looked like really bad orange peel. And they were a bear to fix."
Diesel exhaust aside, oil or other contaminants in the air line or booth filters usually prompt a visit from the fish eye monster. Fran McManus, a marketing specialist with DuPont, says to "make sure you've got a good, well-maintained compressor with proper filtration."Indeed, dirt and other contaminants are a consistent theme among shop owners and paint experts when they discuss paint shop problems. Such problems are usually the painter's fault, says Dan Greenwald, owner of Greenwald's Autobody & Paintworks in Chula Vista and National City, Calif. "[The painter] needs to keep booth doors closed, and he must not come out of the booth with his suit on," Greenwald says. "He should dress and undress in the mixing room."(Incidentally, Greenwald's personal horror story involves a sprinkler system. "We had just opened the shop," he remembers, "and we were final coating the first car we ever did when the sprinkler system went off. Washed the paint right off the car.")Mark Cantrell, owner of McLeod Auto Body in Kirkland, Wash., also places responsibility on the painter. "He has to have good, clean habits," he says. "And he has to keep the gun clean."Industry experts agree. Nearly every textbook and manual on automotive paint application emphasizes painter and paint room cleanliness, starting with a lint-free "shoot suit." The painter should wear it only inside the spray booth, mixing room and booth vestibule, and he or she should store it in an airtight plastic bag.In addition to wearing the shoot suit, refinishers should prevent paint problems by:wearing a lint-free head covering to prevent hair, sweat or dandruff from falling into the finish;avoiding cotton T-shirts because cotton fibers create static charge that will hold dust;wearing lint-free gloves, and washing hands thoroughly before putting on the gloves;storing respirators in airtight bags;prohibiting visitors in the booth.And finally, a painter's duties should be limited to painting. When a refinisher performs other tasks, he or she runs a greater risk of bringing general shop contaminants into the booth on clothing, hair, hands, shoes, etc.Another common mistake is relying on one gun, Allred says. "You can't be a painter with a single gun," he says. "You need a minimum of three-one for the base coat, one for the clear, and one for primers and sealers."Vehicle Preparation
Once the painter is prepared, he or she must ensure that the vehicle is clean. critical element in a deliverable paint job is a well-prepared surface. "Every professional, guaranteeable paint job must have a good foundation," says Jason Bartanen, a technical writer for I-CAR. "That starts with a thorough washing and blowing off of the surface."
Carl Seaboldt, a technical service specialist with PPG, agrees and explains that a clean surface can't be overestimated. "You need to wash it with soap and water and then use a grease remover," he says. "A lot of shops go right to the sanding step, and that just drives all those contaminants into the surface and embeds them there."An equally important step in surface preparation is masking. "The car has to be wrapped properly," Cantrell says. "If you don't have nice tight wraps, with no holes or gaps in the masking, and if the tape isn't pressed down all the way, it can cause leaks, which allows contaminants to drop from that area onto the finish."Next comes the sanding operation, where some shops try to save time. The result: sandscratches. Eric Ashman, national technical manager for Akzo Nobel, explains that the usual cause of sandscratches is skipping steps in the sanding process. "Say you start with 80-grit paper," he says. "Some painters will go from there to 240 grit. That's too big of a jump. To take out those coarse, 80-grit sandscratches you need to go to 120, then 220, then 240. The rule of thumb is: You should never jump more than 100 grits."Such corner-cutting to get more work out the door is probably the primary cause of most paint shop problems. Ashman says many painters weigh the risk and then decide that skipping a step in the preparation process is worth it. "Maybe they can save an hour on a job," he explains. "That's 100 hours for every 100 jobs. Now they have to estimate how many of those jobs will cause a problem for them, and how long it will take to correct it. If, say, one in a hundred is a problem and it takes two hours to correct it, then they may go ahead and take the chance. Obviously, it's something we don't recommend."Another all-too-common practice is "short baking," says Ken Phillips, product manager for Sherwin-Williams. "Shops are under pressure to increase productivity, so they may not bake the vehicle as long as they should," he says. "Some others don't use a sealer when they should. Either way, you're short-changing a system that will work if all the steps are followed."These shortcuts often come back to bite the shop, says DuPont's McManus. "You get guys rushing jobs, not giving the paint enough flash time, piling on heavy coats, things that can manifest themselves down the road," he says. "Then you have to ask: If they didn't have time to do it right the first time, how are they going to find time to do it over?" Doing a sprayout to determine color match is another step that is often ignored, according to Jim Warren, manager of administration and training for BASF. Because of the variations in factory colors, sprayouts are a must. "And you need to document the sprayout on the back of the panel," he says.Warren also recommends preparing the job for a blend. "Most jobs have to be blended," he says. "So if you're doing a fender, prep the door, too."Detective Work
While cutting corners usually means skipping steps in the repair process, it can also take the form of misguided attempts at saving costs. This usually involves using different products from two or more manufacturers, McManus says. Less expensive generic primers and clear coats are a special problem, he says. "Most of those manufacturers don't make color, so when you combine their undercoats and clears with a major manufacturer's base coat, you're asking for trouble. Because the chemistry isn't compatible, you get reactions like delamination and wrinkling."
As any veteran painter knows, the problems that can crop up on a car's freshly painted finish are almost too numerous to count-unless you're Ashman, who says there are 23 common defects. The problems range from alligatoring to wrinkling, although terminology can vary, depending on the source. (In BASF's lexicon, "bits" is another term for dirt or dust.) "And the thing is, you have to know what caused the problem in order to find a remedy," Ashman says. "Sometimes, a painter has to put his thinking cap on and work back through the steps and figure out what went wrong. If you have fish eyes, was there a bottle of Armor All around? Was the paint strainer clean? What about your suit?"In cases like these, just call PPG's Carl Seaboldt Sherlock Holmes. Several years ago, Seaboldt was working as a jobber salesman when he was called to a customer's shop to look at the finish on a 40-ft. tractor trailer. "The guy had painted it two days before," he says, "and when it didn't dry like it was supposed to, he decided to drive it around, hoping it would air dry. Well, that thing was one big piece of flypaper. Everything stuck to it-bugs, paper, feathers, a hamburger wrapper. It was very tacky."Seaboldt set to work trying to determine why the finish hadn't cured. Fortunately, he had an accurate record of the customer's recent paint purchases. A quick comparison of that record against the shop's inventory revealed that there was too much activator on hand. "Just to be sure, I checked the garbage cans and couldn't find any activator cans, so it became obvious that the guy had left out the catalyst when he prepared the color," he says.Seaboldt has found that such incidents of brain-lock aren't uncommon. "A guy gets a phone call in the middle of mixing paint, he comes back and just forgets about adding the catalyst," he says.Another mental error that some shops make is using the wrong solvent. "Guys don't switch to a faster solvent that's appropriate for the weather, and they get solvent entrapment that results in popping or dieback," Seaboldt says. The remedy? "Sand it, and buff or re-clear, depending on how deep the solvent popping goes."Low air pressure can also cause solvent trapping, says Dave McCord, manager of applications, vehicle refinish for Sherwin-Williams. "As more low-VOC and high-solids coatings come on the market, spray gun setup, atomization and air pressure become much more crucial," he says. "The dangers of spraying at low air pressure, particularly with HVLP equipment, can result in solvent popping, loss of gloss and soft films."So what can you learn from this discussion of paint problems? Maybe not much that you haven't heard before but plenty that bears repeating:Keep it clean-the painter, the booth, the gun.Follow label directions-to the letter.Surface prep, surface prep, surface prep.Don't shortchange the system by skipping steps or using cut-rate products.Remember to add the catalyst.Use the right solvent for the temperature.And, oh yeah, watch out for that diesel fuel.

About the Author

Bob Yearick

Bob Yearick recently retired from the DuPont Company after 34 years of service. He was editor of DuPont Refinisher News for nearly 20 years.

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