1Paint Defects 1 (1) Cratering (2) Dust (nibs) (3) Orange peel (4) Sagging(5) Poor opacityIn this section, we will study the cause of defect and countermeasure which will be caused on application process.(click each phenomenon for more detail understanding)
2Cratering / Fish-eyes Cratering (phenomenon from base material) Fish-eyes (phenomenon in paint film layer)The phenomena of cratering is shown that cratering and fish-eyes occurs partly on the paint surface and the film becomes uneven.Causes : (1) Foreign articles (such as waxes) adheres on the painting film. (2) Insoluble foreign articles adhere on the paint film of before touch-dry, and this causes cratering.Cratering and Fish-eyes occurs partly on the paint surface, and the film becomes uneven.
3Cratering / Fish-eyes (cause-result analysis chart) Application workDryingToo thick application of excessively diluted paintsPoor drying of puttyThick application of lacquer type puttyCrateringStrong dissolvability of topcoat paint.Insertion of polyester putty between lacquer paint filmsAbsorptive puttiesPoor sanding of puttyExcessive adding of non-blushing thinnerPaint / PuttyOthers
4Measures Cratering / Fish-eyes Precautions Remedy Circumstances Facility & EquipmentMost of the troubles can be resolved by avoiding the factorsPrecautionsApplication workMaterialsSlight fish-eyes shall be repaired with dry mist spraying.To avoid the phenomena of cratering / fish-eyes, it can be solved by avoiding the factors as mentioned on the previous slide (cause-result analysis chart).(Remedy) : Abrase off the cratering / fish-eyes area completely from topcoat surface, then repaint.RemedyLarge sized (cratering) shall be abraded off completely after drying, and repaint.
5Dust (Nibs) Popping appears on the film surface. Popping The phenomena of dust (nibs) is shown that popping appears on the film surface.Causes : Foreign articles adhere on the film before touch-dry, and the part of film projects.Popping appears on the film surface.
6Dust (cause-result analysis chart) MaterialsFacility & EquipmentShortage of booth air pressureInsufficient filtration of paintDefects of booth filtersInsufficient cleaning of spray gunsDefects of air cleanerDustDusty working clothesInsufficient cleaning of the painting work floorInsufficient cleaning of car bodyTrash of masking papers (newspapers, etc)Insufficient cleaning of spray gunCircumstancesApplication works
7Measures Dust (Nibs) Precautions Remedy Keep painting area clean, and free from trashes and dusts.PrecautionsPrevent working area from floating dusts by watering the floor before painting.Wear anti-dust working clothes, and use proper masking paper and tapes.To avoid the phenomena of dust (nibs), it is necessary to (1) keep painting area clean, and free from any trashes and dusts inside workspace, (2) to prevent workspace from floating dusts by watering on the floor before application work, (3) to wear anti-dust working uniform, and use proper masking papers and tapes.(Remedy) : Abrase off small nibs with using a knife or grinding stone (#1500～#2000), and polish up the area with “Fine” or “Extra-fine” compounds.RemedyAbrade off small nibs with a knife or grinding stone, and polish it up with compounds
8Orange peel Paint surface become uneven like orange peel. The phenomena of orange peel is shown that paint film surface become uneven just like orange peel.Causes :During the process of forming film of paint, convective phenomenon (vortex) occurs in the non-dried film layer when solvent is evaporated. The earlier stoppage of convection in the process causes orange peel.Paint surface become uneven like orange peel.
9Orange peel (cause-result analysis chart) Application worksCircumstancesHigh temperature of car bodyToo fast blowing speedThin paint filmLow spray pressureHigh temperatureInsufficient spraying emission volumeToo fast gun speedToo long spray gun distanceOrange peelToo quick evaporation of thinnerToo big size of spray gun nozzle (insufficient atomization of the paint)Too high viscosity of thinnerDefects of spray pattern (insufficient cleaning of spray gun)Low liquidity of paintMaterialsFacility & Equipment
10Measures Orange peel Precautions Remedy Slow evaporation speed of solventPrecautionsDecrease viscosity of paint.Maintain liquidity of paintTo avoid the phenomena of orange peel, it is necessary to (1) control evaporation speed slower of solvent, (2) decrease viscosity of paint, (3) maintain liquidity of paint. However, excessive dilution may cause running of the paint.(Remedy) : Apply water sanding around orange peeled area with #800～#1000, and polish up it gradually with using medium→fine→extra fine compounds.RemedyApply water sanding (#800～#1000), and polish up gradually with compounds (Medium→Fine→Extra fine).
11Paint film partly becomes too thick and the paint sags. SaggingPaint filmSubstrateThe phenomena of sagging is shown that paint film is partly becomes too thick, and the paint film causes sagging.Causes : The paint dries too slowly, and is in liquid condition for long term. This causes sagging and running.Paint film partly becomes too thick and the paint sags.
12Sagging (cause-result analysis chart) CircumstancesApplication workLow temperature of car body Thick paint filmLow temperatureLow spray pressureToo short spray gun distanceToo much spraying emission volumeDefective spray patternSaggingToo big size of spray gun nozzle (insufficient atomization pf paint)Too slow evaporation of thinnerToo low viscosity of paintDefective spray patternMaterialsFacility & Equipment
13Sagging Measures Precautions Remedies Make set-to-touch time faster Adjust spray pattern, gun distance, and gun speed to proper level.Use proper thinner to avoid excessive coating.Overall sagging : abrade off whole area, and refinish.To avoid the phenomena of sagging, it is necessary (1) to make set-to-touch time faster, (2) to adjust spray pattern, gun distance, and gun speed to proper level, (3) to use proper thinner to avoid excessive coating.(Remedy) : In case of overall sagging, abrase off whole sagging area, and refinish it. On the other hand, in case of slight sagging, abrase off the sagging area with waterpaper (#800～1000). After drying the surface, apply compound (Fine→Extra fine)gradually in order to polish surface.RemediesSlight sagging : abrade off the sagging area, then apply compound (fine→extra fine )
14Poor opacity (Poor hiding power, or Lack of hiding) Poor pigmentationInsufficient film thicknessThe phenomena of poor opacity (poor hiding power, lack of hiding) is shown that the color of undercoat is not hidden.Causes : (1) Poor pigmentation (2) insufficient film thicknessThe color of undercoat is not hidden caused by poor pigmentation, or insufficient film thickness
15Poor opacity (cause-result analysis chart) Application worksInsufficient agitationToo thin film coatingToo much dilutedPoor opacitySpecific nature of tinterMaterialsLack of hiding power
16Poor opacity Measures Precautions Remedy Spray paint in proper film thickness after sufficient agitationPrecautionsAvoid excessive dilution.Apply back-up undercoat of similar color shade in case of poor hiding colors.To avoid the phenomena of poor opacity, it is necessary to (1) spray paint in proper film thickness after sufficient agitation, (2) avoid excessive dilution, (3) Apply back-up undercoat of similar color shade in case of poor hiding colors.(Remedy) : Repaint until the undercoat is completely hidden.RemedyRepaint until the undercoat is completely hidden.
17Please refer to the summary of each regulation of safety hygiene in which is regulated by each country.