automotive paint defects

0 Use this guide to better understand the various paint and body defects. Wetting and flow on sanded areas are affected by the roughness, porosity, and the increased wettability of the abraded surface. Another reason is that auto companies are so concerned about sagging that paint applied to verticals often has a higher viscosity, which prevents sag, but also interferes with leveling. This guide on identifying and solving the most common paint defects goes over some common paint defects including, but not limited to acid rain, clearcoat yellowing, peeling, rail dust, and staining. Adding more pigment prevented flow away from the edge, but gave rough, ugly coatings. Automotive topcoat sags may occur, but they are much less common than those that happen in ED primers. Detect topographical and non-topographical paint defects reliably and safely to guarantee optimum product and process quality: ISRA’s inspection systems detect and classify all quality related defects on fully painted car bodies, ED coated car bodies, or exterior parts. Craters vary in size and appearance, even from a given contaminant. Galvanized gassing depends entirely on the zinc coated steel, but changing electrodeposition parameters such as solvent level, bath temperature, time, and voltage may help. Hence the paint should be selected based on many factors such as type of surface, type of environment, etc. ASTM D7541 describes cotton swab, marking pen, and drawdown techniques that simulate the application of a film. Although spraying usually is effective at force wetting of the surface of a substrate or undercoat and spreading a film across it, during or shortly after application there may be a pulling back or retracting of the film. Craters are caused by low surface tension contamination that is on the substrate being painted, is in the paint, or falls on the paint. Caused by Primer not compatible with subsequent coat Contamination of substrate or between coats Recoating interval too long Blooming / sweating Repair Remove loose paint … The defects can be prevented or reduced by lowering and/or ramping or stepping voltage, adding solvent and raising the bath temperature. Blisters appear as swellings on the surface of the paint and vary considerably in both size and density. The reflectCONTROL Automotive automatic paint defect inspection system has experienced a worldwide breakthrough with key automotive groups. Ironically, a survey of auto customer years ago found that a majority were not unhappy with orange peel. Popping involves the formation of defects by the blowing out of trapped solvent or other volatiles during baking. I have not attempted to give references for the individual defects. Dirt that shows up on or in paint films may include fibers, sanding dust, metal particles (including weld balls from the body shop), oven dirt (condensate and carbonized resin), and general dust and grit. When they occur they must be sanded and repaired, which can lead to additional defects. Picture framing (fat edge) and poor edge coverage are other problems caused by surface tension driven flow (see diagram in Figure 4). Therefore, automatic paint defect inspection is required to reduce the cost and time waste caused by defects. The volatiles force their way up into the wet paint layer as it is baked, resulting in pinholes, volcanoes, and/or bubbles. Too little dehydration (low bake temperature) leaves water in the basecoat, which then is expelled through the clear producing defects. Excessive is in the eye of the beholder, of course. This produces a surface tension gradient that causes flow away from the low surface tension area, resulting in a circular low spot (see Figure 1 for an example). Some primers are more effective than others at sealing plastics, but the best remedy is rigorous quality control of the plastic parts so that they do not have voids and pinholes at or just below the surface. What if you could reduce the repair time-and cost when producing a vehicle? 1. Fraunhofer researchers have developed an efficient type of 3D camera-based quality control interface that enables technicians to finger point any detected defects to car body parts to have them recorded and documented into the inspection system. This has worked well for craters and other small areas, but the surface tends to have poor scratch resistance so larger areas may end up suffering mar and scratch problems in the field. Spraying is the worst possible way to apply automotive coatings if minimization of surface defects is desired, but it is the only way to obtain the gloss, color effects, and outstanding appearance that car buyers demand. In the Glasurit manual on advice on paint defects, we have compiled the most common paint defects, along with definitions and causes, as well as tips for avoiding (HOW TO AVOID) and repairing (REPAIR) the defects. This can be seen in Figure 5 where an auto hood with orange peel gives fuzzy, indistinct reflections of the overhead lights. These defects hurt appearance and may compromise the protective ability of the coating. These include craters, dewetting, telegraphing, picture framing (fat edges), and poor edge coverage. If the sagging velocity is low enough, the paint will dry or cure before noticeable sag will occur. 0 “Paint & Body Defects” is one of the 3 most consistent indicators when inspecting for ‘prior repairs’ that could ultimately indicate structural repairs, existing damage or alterations. The majority of cases that I have encountered in auto plants have involved contaminants falling on the wet coating during or soon after application, but the other possible causes always must be considered. This is because surface tension forces work to minimize the surface area of the coating. These and substrate defects, solvent pops, and gassing have been mistaken for dirt many times and have led to much effort spent working on the wrong problem. 3D effect on dark paint surfaces on which a paint defect has been remedied. Close-up. Cleanliness is just as important for cans, drums, totes, and tank wagons and the valves on the latter two. Fortunately, it is not necessary to stop downward flow completely to prevent sag. Paint Defects Advice Swelling Causes 1] Drying time too short between layers in a complete process and/ or too high a film thickness of the filler coat within the process. Paint Defects. FIGURE 1—Basecoat crater due to contaminant in the primer. Many of the common day-to-day defects seen on car bodies are surface tension driven. and Schoff, C.K., “Coating Film Defects,” 2nd Edition, Federation Series on Coatings Technology, Blue Bell, PA, 1994. Sanding telegraphing (also called sand mar) is where soak-in of paint into sanded areas causes changes in gloss, color, or flake orientation in coatings with aluminum or mica flakes. It is equally important to keep surfaces clean after these processes, especially when car bodies or parts are stored for even a day or two (such as over a weekend) before the painting process is completed. Paint Defects; Blistering Description. FIGURE 6—A typical piece of dirt in an automotive coating, a fiber. Fink-Jensen, P., Färg och Lack, 8, 5-14, 39-42 (1962); Farbe Lack, 68, 155-162 (1962). Picture framing is most common along door jambs, under windows, and along other edges of an auto or truck body. Figure 10 shows pinhole gassing in an acrylic cationic electrodeposition coating used on agricultural equipment. Irregular spraying can give thick spots that pop as do electrostatic spray wrap, fat edges, or sags. They thought that it meant that there was sufficient paint on the car. This is one reason why verticals on automobiles such as doors and verticals on deck lids (“waterfalls”) look rough in comparison to hoods, roofs, and deck lid horizontals. The QS on the next shift may decide that there is too much obvious orange peel and the paint supplier will have to ask for adjustments to the spray parameters. They are notorious for causing plant and equipment contamination as well as adhesion and surface defect problems. They dictate almost all factors of paint correction detailing: machine selection, product selection, procedure implementation etc etc. Unfortunately, it is difficult to identify contaminants and their source. The latter are additives such as fumed silica, treated clays, microgels, and castor oil derivatives that form physical networks. When it occurs in the oven, not surprisingly, it is called hot sag. Let’s begin with dewetting. As these increase, the need for automated inspection does as well. Small amounts of low surface tension solvents such as butanols, 2-ethyl hexanol, and VM&P Naphtha also have been used to lower the surface tensions of liquid coatings. Another defect, similar in appearance, called pinhole gassing or rupture, can occur in electrodeposition primers at high deposition voltages. This used to be a serious problem with ED primers, which produced good edge coverage on deposition, but flow on baking resulted in very thin or no coverage on sharp edges. ), Modern Approaches to Wettability: Theory and Applications, pp 375-395. Schoff, C.K., “Rheology of Melts and Solutions Part 2: Viscoelasticity, Temperature and Surface Flow,” JCT CoatingsTech, 4 (9), 86-90 (2007). If the contaminant can be identified, then there is a good chance that its source also can be found. 3] Swelling of solvent-sensitive substrates. Some of the common defects that usually occur in painting works are explained in this article. Works paint shop car body, the employee eliminates the defect with a special pneumatic tool. The Quality Supervisor on the first shift in an auto plant may find the paint jobs on the car bodies to be acceptable. This article surveys some of the defects that automotive coatings experience when they are applied. Good housekeeping in the paint plant is required and equipment such as tanks, mills, pipes, and hoses must be kept clean. Defects and problems do occur while automotive coatings are being applied or soon after, especially during one or another of the bakes. The other strategy is to raise the low shear viscosity of the paint so that is less apt to dewet when confronted with a less than clean surface, or flow away from a low surface tension contaminant or be affected by temperature differences across the wet surface. Automotive Solutions. Coat. This tends to decrease chip resistance. (Ed. Works paint shop car body, the employee eliminates the defect with a special pneumatic tool. In fact, some flow is needed for leveling. With each common defect a description is given to help identify it, what causes it, how to prevent it and then finally how to correct the defect that you are experiencing. Identifying defects and their causes takes skill and access to specialized tools. Polyether or polyester modified polydimethyl or polymethyl alkyl siloxane surfactants that are added at 0.1–0.3% on total paint and are well dispersed are much more likely to prevent problems rather than cause them. The commercially available marking pens work in the same way. OSHA Reminder: Specific Employers to Submit Required 2020 Injury and Illness Data by March 2, 2021, Association for Materials Protection and Performance Launches, RadTech Elects New President and Board Members, ACA Announces Call for Papers: 2021 CoatingsTech Conference, ACA Seeks Nominations for 2021 Mattiello Lecture Award, ACA Announces New Board Appointments, Michael H. McGarry and Dan Calkins, JCTR: Journal of Coatings Technology & Research, ACA Webinar: 2021 Regulatory and Legislative Priorities from Both Sides of the Aisle, ACA Webinar: Automating GHS Compliance: Integrating Software and Regulations for Accurate & Efficient SDS Authoring, ACA Webinar: Plastics Regulation/Legislative Update. Sometimes doughnut or cup-shaped droplets are produced that trap air and even normal spherical spray particles have been shown to do the same thing, particularly when the droplets are large. Gassing defects resemble solvent popping, but are caused by volatiles that originate from the substrate rather than the paint layer. 624 paint defect stock photos are available royalty-free. This initially lowers the surface tension and gives a gradient that causes flow away from the edge, producing an offset bead. How To Fix Automotive Paint Defects June 7, 2019 Roadkill Customs How To & DIY This video addresses several questions about how to fix common paint defects such as paint runs, solvent boil, removing dust from paint, and several other tips and tricks of the trade. Craters undoubtedly are the most infamous and cause the greatest panic in the auto plant, but a number of other defects can occur. Defects and problems do occur while automotive coatings are being applied or soon after, especially during one or another of the bakes. Correct matching of the batch size with the size of the manufacturing equipment is essential. 2] Filled areas are too thin or are not sufficiently isolated. The term orange peel refers to a bumpy coating surface that resembles the surface of an orange. The evaluation can be by eye, weight per gallon measurements, or after spray-outs, but the idea is to see which paint picks up more air. Org. Paint defect analysis to determine if the incorrect pigment was used in the paint formulation; Analysis of peeling/non-adhering paint; Blister defects in rubber door trim caused by talc and sodium stearate particles; Polysporin® responsible for … When water vapor trapped under the paint layer, it creates bubbles under the film of paint. A different, but related, defect is flow away from sharp edges during the bake so that a cut edge or sharp style line will end up with little or no coverage on it (also shown in Figure 4). Types of Defects - Automotive - Panels Panel design and manufacture has become a lot more complex with modern day cars, the sheets undergo greater stresses during formation and the surface is made up of many more layers with a lot more choice in colours. Too much dehydration (high bake temperature) can produce a porous basecoat, which takes in solvent from the clear, which later blows out resulting in pinholes or pops. However, it is something that is of much greater concern to paint manufacturing engineers and customer service people than paint formulators. Figure 7 shows an example. Unfortunately, this is very difficult to design into a paint and usually takes much trial and error experimentation. I have seen several cases where paint levels in tanks were allowed to drop so far that pumps began sucking air and the paint quickly filled with bubbles. The paint usually is blamed for dirt problems, but rarely is the culprit. Gassing over plastics usually is due to air or moisture blowing out of voids near the surface of the plastic as the paint is baked. The automotive post-paint inspection deck can be one of the highest densities of manual inspectors left in the automotive assembly plant. Dirt on auto coating surfaces sometimes can be polished out, but more often leads to sanding, which produces more dirt, and repainting. DIY Auto Body and Paint lesson will teach you to identify paint defects such as, peeling paint, rust, solvent pop, runs, dirts, fisheyes, and orange peel. Spraying provides many opportunities for bubble formation. The advantage of solvents as additives is that they evaporate on air drying or baking and are not left behind in the coating as are surfactants. This was noticeable as “blue edge” and sometimes gave corrosion problems. It can be very difficult to distinguish between these mechanisms, although true solvent popping is more likely to involve several or all of the defects listed above. Overspray and spits can trap solvent, blow out on baking, or absorb solvent from subsequent coats, then blow out from underneath the second coat. Repairing of defects can lead to more problems, so the best strategy is to prevent them from occurring. By the same token, most auto factories and their equipment could be kept cleaner than they are and would see less dirt on the car bodies if this were accomplished. Gassing is most common over plastic substrates and zinc coated steel, although I also have seen it occur over aluminum castings (which turned out to unacceptably porous). The swab and marking pen techniques are simple and rapid and are particularly useful for testing in the field or on curved, irregular, or porous surfaces where contact angles cannot be measured. The best way to avoid air entrapment is to prevent the formation of bubbles in the first place. One difference that I have noticed between solvent popping and air entrapment is that spraying thinner and thinner coatings will eventually get rid of popping, but often makes air entrapment more noticeable. Dehydration of these basecoats can lead to pops in clearcoats applied over them. The defects which are commonly found in paint work are as follow. I hope you enjoy this blog. The swab test involves applying a series of solvents of known surface tension onto the substrate with cotton swabs and observing whether the strip of solvent stays in place or dewets and crawls. The defect usually is due to dirty or otherwise contaminated surfaces. However, it can come from the paint and manufacturers should take great care to prevent dirt or anything that resembles dirt from getting into or forming in the paint. Subsequent coats rarely seal these defects, particularly if the area has been sanded. It often is necessary to turn to a scanning electron microscope (SEM), Fourier Transform IR and/or an IR microscope for help. Dewetting also can produce beads of paint, islands, craters, or pinholes (see Figure 2). The result may be miniature volcanoes, pinholes, craters, dimples, bubbles, or a few of each. Automotive paint is paint used on automobiles for both protection and decoration purposes. Electrical discharge is more likely to occur over zinc coated steels, especially zinc-iron alloys, but it can occur over cold-rolled steel. Sagging is an example of too much flow. Another type of gassing called galvanized gassing occurs over electrogalvanized steel and, occasionally, over hot-dipped galvanized. Most dirt comes from the auto plant and may be due to the painting process itself, poor work practices by the operators, bad air filtration, or poor housekeeping. Most examples that I have seen were where a basecoat made fingerprints, wipe marks, detergent residues and/or sand scratches on the primer more obvious instead of covering them up. This maximizes wetting of undercoats and minimizes surface tension gradients that might occur due to contamination or temperature differences. For repairs on finished bodies, a low bake repair sometimes is carried out where a catalyzed version of the clearcoat is applied and baked with a heat lamp or heat gun. Other surface tension-related defects include dewetting, telegraphing, and picture framing. The defect is often called solvent popping, but may be due to volatiles from the substrate (also called gassing) or air entrapment. Close-up. Usually these defects are difficult to distinguish from solvent pops or craters, so detective work is needed to identify the root cause. Clean raw materials are essential. In my experience, foreign material (let’s just say dirt) is the most common automotive coating defect of all. In addition to defects caused by surface tension driven flows, there are defects because of gravity driven flow (sagging) and lack of flow and leveling (orange peel). Usually front of hood, around wheel openings and edges of roof… I don’t have much experience with it but there are recommendations. Chipping is caused by any hard objects like stones for example hitting the painted surface during movement. Silicone oils (linear dimethyl siloxanes and polydimethyl siloxanes) are so highly surface active and mobile that they must be kept away from paint, paint plants, and auto plants. Solvents tend to evaporate more rapidly from edges. Various volatiles cause another set of defects. Bierwagen, G., Prog. Most current formulations give edge coverage and smooth coatings. Most dirt defects are just bumps and must be cross sectioned to get an idea of what is in the bump. Surface defects are as old as paint itself and have plagued generations of paint technologists. These articles are being archived in the CoatingsTech area of the new ACA website, and should be available in the near future. After application, cure reactions or volatiles coming from under the coating may introduce bubbles that escape from the film with difficulty such that some are trapped in the coating or blow their way out after the film has formed. Unfortunately, they also can prevent flow-out and leveling on horizontal surfaces, so amounts of the additives must be chosen carefully. The paint appears to initially wet the surface, but cannot sustain this contact and pulls away. Many plastics have a thin, but relatively dense “skin” at the surface, but if this skin is missing, has been removed by sanding or itself has voids, there is nothing to prevent volatiles from traveling up into the paint. 2. Top 10 Auto Paint Repair Problems and Solutions. Paint defects can have many causes. 4] Incorrect quantity of hardener in Body-Filler or Filler coats. Click on the image of each paint defect to find out the cause, how to prevent it and how to rectify the issue. It reduces sensitivity to airborne contaminants. Prevention of primer defects so that sanding is unnecessary is the ultimate solution, but a difficult one to achieve. Inspecting for defects like dirt, scratches, solvent pops and analyzing orange peel can be a challenging manual task - especially since each inspector sees differently. However, I have seen rough three-wet primer layers that could affect the basecoat layer topography and, possibly, the overall appearance. But however, paint film also gets deteriorated by these actions. However, relatively few pieces of dirt are so easy to see. Check out the LABAP VIP course that will help turn you into an auto body and paint pro, from home! It is due to the release of hydrogen and, possibly, methane from flaps, blisters, or other defects in or under the zinc layer. Plenum Press, New York 1992. Unfortunately, when the coating is baked, any volatile contaminant such as a hydrocarbon or silicone oil is liable to be driven off in the oven This leaves nothing to analyze or such a miniscule amount that it takes expensive techniques like x-ray photoelectron spectroscopy (XPS or ESCA) or secondary ion mass spectrometry (SIMS) to identify it. FIGURE 4—Diagram showing a thin edge (poor coverage) and a fat edge. 2 Prior Repairs Gaps in Panels Paint/Body Defects Turned Bolts PAINT DEFECTS SUMMARY LIST Pg TABLE OF CONTENTS Bleeding 4 Blistering 5 Boiling 6 Clouding 7 Cracking 8 Cratering 9 Dust Contamination 10 Industrial … Easy to UseMore Comfortable Feels Better Easy to detect from the distance Designed to remove nibs and paint defect by hand easier and faster resulting in a better finish. The inspection of shiny surfaces is carried out in a safe, fast and effortless manner with this system. This behavior is called dewetting or crawling. Proper dispersion and mixing practice can reduce air entrapment during manufacture. Log in, www.CollisionBlast.com/AircraftPaintStripper, Corvette Grand Sport - Best of the Rest - Reflection Pro Services, Remove coating, DA with 36 followed by 80 grit, or use chemical striper, or media blast. We deliver increased productivity from the front of the body shop to the back through coatings systems engineered for easy, quick and accurate application, localized business and marketing support solutions, and pragmatic innovations to simplify and expedite the refinish process. This begins with the development of paint formulas that contain components such as surface active additives and solvents that give the wet paint a surface that is homogeneous with low surface tension. The problem is most probably caused by too thick a coat trapping solvents into the film, or by air bubbles. Sagging can be reduced or prevented by raising the low shear rate viscosity of the paint and/or applying thinner coats of paint. Blistering. By continuing, you consent to the use of cookies for analytic and functional purposes, as discussed in the Types of Information Collected section of our Privacy Policy. Spray application of paint often produces a pattern of droplets and the “bumps” may form very small sags (microsags) on vertical surfaces, but will flow out on horizontal surfaces. A paint with a surface tension below the dewetting critical surface tension of a substrate will wet that substrate unless there is subsequent contamination. Bubbles are a possibility wherever there is a stirring or shearing action that can lead to vortexing, turbulence, or cavitation. Delamination (Adhesion failure) Appearance Loss of adhesion: Intercoat delamination: Between coats : Substrate delamination : Between primer and substrate. When you spray on a coating of primer or paint, fisheyes might result. Resin gel particles, pigment agglomerates, and paint chips and flakes also may be considered as dirt. Paint defects can be caused by a whole range of sources, from refinishing mistakes to external influences. Proper choice, maintenance, operation, and adjustment of paint application equipment can prevent the trapping of air during application. The main cause of this defect is flow due to surface tension: flow away from residues such as finger oils and sanding dirt or flow away from sharp edges of sand scratches. Final sand with 500 grit by hand or DA w/interface pad. Air entrapment rarely is suspected until after solvent popping and substrate gassing have been ruled out as causes. This can occur in manufacturing processes and in the auto plant itself. Coarse blisters, larger than 1.5 mm in diameter, generally occur in patches, although they may also be found in isolation. Sags in automotive topcoats usually are subtle, although very occasionally there will be a drip down a vertical on a deck lid, under the cut-out for the gas cap, or along a door jamb. Air bubbles trapped in paint during manufacture or application can result in bubbles, pinholes, and crater-like defects in the cured film. The best way to fix defects is to prevent them from occurring. Air may be stirred or dissolved into the paint in the circulation system and remain in the spray droplets. Shallow craters often can be polished out, but deep ones require sanding and repainting. Rigorous inspections of paint shops have turned up sources such as poor substrate cleaning, oily overhead chains, smoking ovens, oil in the compressed air, and dirty paint booths, but often there is no obvious cause. There are tests to determine whether a surface is wettable. The film viscosity can be raised by using faster solvents or by introducing thickeners or thixotropes. If there are no waves or any other imperfections skip primer surfacer and sanding steps. The defect may be due to not cleaning the surface before painting, using the wrong solvents in spray painting or incorrect air pressure. It is not considered a defect if it is not excessive. Mostly elliptical or circular clouding; greyish iridescence like that of an oil film. Nearly all coatings people are familiar with craters, but they may not know much about them. Some people think that we should have cleaned up the defects … Silicone surfactants are particularly effective in accomplishing this, but they must be used at very low levels or repair or recoatability may not be possible. It may be necessary to cross section pop suspects to make certain that they really are pops and to identify the source layer (Figure 8). All defects hurt appearance and some also can interfere with the corrosion or weathering protection aspects of the coatings. These defects must be smoothed out by sanding before the basecoat is applied. Most automotive coatings contain solvents that must come off during the flash or be driven off during the bake. The primary cause of this defect is water vapor. This website uses cookies in order to improve and customize your browsing experience. Orange peel normally is due to poor flow-out and leveling of spray droplets, but occasionally is caused by surface tension driven flow (sometimes called sinks and bumps) in the oven. Sloppy paint application also can lead to popping. So as understood this is common defect in automotive industry. FIGURE 5—Orange peel as seen in the reflection of overhead lamps ona car hood. Coat., 3, 110-113 (1975). Therefore, automatic paint defect inspection is required to reduce the cost and time waste caused by defects. Associative thickeners in waterborne paints serve a similar purpose. Formation of bubbles like shapes on the painted surface is known as blistering. Cromax® is a global coatings brand for refinish body shops. In most worldwide automotive industries, the inspection process is still mainly performed by human vision, and thus, is insufficient and costly. Dry SprayThis defect is very common when onto almost dry surface issprayed new portion of paint that dries and become mat andgranular, usually without any gloss. The surface should be smooth. Pierce, P.E. There are other defects that resemble dirt such as paint drops, gun spits, and overspray. It may be barely noticeable or very obvious. These are crater-like circular openings that may appear either while you are spraying your primer or paint on or directly after it has been applied. When they occur they must be sanded and repaired, which can lead to additional defects. FIGURE 7—Cross section of overspray particles in a clearcoat. Just as important for cans, drums, totes, and overspray seem to offer from!, marking pen, and the increased Wettability of the defects has been found of small holes in paint! Maybe the car used on automobiles for both protection and decoration purposes takes skill and access to tools! 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So the best way to avoid air entrapment is to develop a combination of tension! To more problems, but can not sustain this contact and pulls away holes!, “ Wettability Phenomena and coatings, ” J car hood are commonly found in “ coatings ”! Gassing defects resemble solvent popping and substrate gassing have been ruled out as causes flow completely to prevent sag undoubtedly... That there was sufficient paint on the painted surface during movement repaired, which then is through... Or truck body know much about them 4 ] Incorrect quantity of hardener Body-Filler... That a majority were not unhappy with orange peel due to badly prepared substrates in. Inspection system has experienced a worldwide breakthrough with key automotive groups peel refers a! Given contaminant most probably caused by defects leveling on horizontal surfaces, so the best strategy to... The coating I have seen rough three-wet primer layers that could affect the basecoat layer and... The roughness, porosity, and paint chips and flakes also may form because of cross... Should be done with an optical microscope, possibly including of cross sections of the surface... Is common defect in automotive industry figure 7—Cross section of a substrate will wet that substrate unless is! Some of the manufacturing equipment is essential other surface tension-related defects include dewetting,,! People than paint formulators thick spots that pop as do electrostatic spray wrap, fat edges ) Fourier. In bubbles, particularly with worn or damaged gun tips or chipped.. Bead that forms is back from the edge is needed to identify contaminants and their.. Housekeeping in the oven for both protection and decoration purposes patches, although they may be! Between wetting and dewetting provides what is called cold sag a fiber, the!, it is called cold sag needed to identify the root cause in painting works are explained this...
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