Paint Defects 1 (1) Cratering (2) Dust (nibs) (3) Orange peel (4) Sagging (5) Poor opacity In 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)

Cratering / 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.

Cratering / Fish-eyes (cause-result analysis chart) Application work Drying Too thick application of excessively diluted paints Poor drying of putty Thick application of lacquer type putty Cratering Strong dissolvability of topcoat paint. Insertion of polyester putty between lacquer paint films Absorptive putties Poor sanding of putty Excessive adding of non-blushing thinner Paint / Putty Others

Measures Cratering / Fish-eyes Precautions Remedy Circumstances Facility & Equipment Most of the troubles can be resolved by avoiding the factors Precautions Application work Materials Slight 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. Remedy Large sized (cratering) shall be abraded off completely after drying, and repaint.

Dust (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.

Dust (cause-result analysis chart) Materials Facility & Equipment Shortage of booth air pressure Insufficient filtration of paint Defects of booth filters Insufficient cleaning of spray guns Defects of air cleaner Dust Dusty working clothes Insufficient cleaning of the painting work floor Insufficient cleaning of car body Trash of masking papers (newspapers, etc) Insufficient cleaning of spray gun Circumstances Application works

Measures Dust (Nibs) Precautions Remedy Keep painting area clean, and free from trashes and dusts. Precautions Prevent 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. Remedy Abrade off small nibs with a knife or grinding stone, and polish it up with compounds

Orange 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.

Orange peel (cause-result analysis chart) Application works Circumstances High temperature of car body Too fast blowing speed Thin paint film Low spray pressure High temperature Insufficient spraying emission volume Too fast gun speed Too long spray gun distance Orange peel Too quick evaporation of thinner Too big size of spray gun nozzle (insufficient atomization of the paint) Too high viscosity of thinner Defects of spray pattern (insufficient cleaning of spray gun) Low liquidity of paint Materials Facility & Equipment

Measures Orange peel Precautions Remedy Slow evaporation speed of solvent Precautions Decrease viscosity of paint. Maintain liquidity of paint To 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. Remedy Apply water sanding (#800～#1000), and polish up gradually with compounds (Medium→Fine→Extra fine).

Paint film partly becomes too thick and the paint sags. Sagging Paint film Substrate The 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.

Sagging (cause-result analysis chart) Circumstances Application work Low temperature of car body　 Thick paint film Low temperature Low spray pressure Too short spray gun distance Too much spraying emission volume Defective spray pattern Sagging Too big size of spray gun nozzle (insufficient atomization pf paint) Too slow evaporation of thinner Too low viscosity of paint Defective spray pattern Materials Facility & Equipment

Sagging 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. Remedies Slight sagging : abrade off the sagging area, then apply compound (fine→extra fine )

Poor opacity (Poor hiding power, or Lack of hiding) Poor pigmentation Insufficient film thickness The 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 thickness The color of undercoat is not hidden caused by poor pigmentation, or insufficient film thickness

Poor opacity (cause-result analysis chart) Application works Insufficient agitation Too thin film coating Too much diluted Poor opacity Specific nature of tinter Materials Lack of hiding power

Poor opacity Measures Precautions Remedy Spray paint in proper film thickness after sufficient agitation Precautions Avoid 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. Remedy Repaint until the undercoat is completely hidden.

Please refer to the summary of each regulation of safety hygiene in which is regulated by each country.