Generally, due to insufficient cleaning or the bottom surface contamination, contamination or poor spray tool environment or a curing agent or diluent such as a solvent Is not complete air bubbles are stirred or bubble, Will spray simultaneously, while the water vapor generated by bubbling defects typically occurs after a few minutes up to more than a month after spraying the shortest.
Under normal circumstances, the coating process Is always inevitably mixed into the gas in the coating, and even water vapor. For example: the mixing process the incoming air still not fully defoaming, during spraying compressed air into the porous substrate or substrate adsorbing moIst air and water vapor and the like. However, these bubbles coating itself should be able to eliminate the drying process itself, but sometimes causes air bubbles are varied, it Is difficult to explain by a single mechanIsm. But the basic principle Is the following bubble generation process, under normal circumstances, after spraying the coating during formation of the paint film due to the surface tension of the bubbles can rIse to the surface of the film, the bubbles rIse when heated, expands, until the surface break, then after leveling to give a flat film. Therefore, in all aspects of the above, no matter which part Will affect the abnormal bubbles dIsappear. During film formation, the solvent evaporation Is too fast, the liquid paint vIscosity increases too fast, increasing the surface tension Is not conducive to defoaming, Is not conducive to leveling.
1. Film to high humidity or water immersion process, since the moIsture penetration film next, when the vapor pressure reaches a sufficient degree that Will produce blIstering. Sun exposure can accelerate the occurrence of thIs phenomenon.
2. Improper bottom surface cleaning process. When a new mill basecoat coating, since the wet milling salt contained in the water between the metal and the primer or topcoat retention, and finally a water wash coating surface quality was poor, and the impurity ions contained in the deposited on the surface, not fully water or wet to dry thoroughly, are enough to cause blIstering. Further, when using bottom benzine, since there Is a water-soluble additives or impurities contained in gasoline, it Is also extremely easy to cause such defects.
3. The materials used do not match, or Is not used as diluent. Diluted dIsproportionate or adverse impact diluent. Insufficient quality Is poor, and too quick drying diluent dilution ratio, high pressure air spray gun, spray paint dry film to a substrate so that the porous, Is sufficient to cause generation of bubbles. Used paint thinners, the water content must not exceed 0.5%, but higher water content generally nitro diluent, 2K-paint Is to be sprayed, not be used Nitro diluent. Particular attention to the situation and the high pressure lance too quick drying with a diluent, it Is easy to air or moIsture ash Is enclosed in the paint film.
4. The film Is too thick. Insufficient drying time, and too thick a primer coating, the primer Is sufficient to cause the solvent can not evaporate. ThIs problem usually occurs after the spraying time Is less than or solvent evaporation in too short a time interval in the two spray coating, the temperature rIse when excessive force premature. ThIs failure causes, generally have a more significant features: many and heavy flat facade less light. ThIs Is because the thickness of the coating Is related to easily obtain a thick film on a plane.
5. The air or air from the delivery tube, the factory tools, old paint, contributing to the foaming of an aqueous impurities, oil and dirt.
6. The inferior portion of the putty and priming effect. We understand that some of the current prices on the market in extremely low priming and putty, which uses excess filler to reduce costs, these primer or putty poor water resIstance, when the humidity Is too large, resulting in the absorption of environmental moIsture, and then back to form a topcoat prickly heat or blIstering.
7. Inappropriate additives. To prevent problems added to the paint primer or additive, may seriously impair resIstance to foaming.
8. Effect or repair of old paint before. Old paint or repair of surface contamination before, can also cause foaming problems. Waxes such as polIshing, cleaning or other materials.
9. Triturated polyester putty, micropores absorbed by the wet grinding process or persIstence water vapor, Will produce foaming problems. After the putty mill, dry compressed air should be at room temperature before braking force Is set to one hour after spraying the primer coating.
10. Putty fill or gray eyes not to fill the two primers and the closure on the polIshed microporous topcoat defect directly, so that the substrate in the presence of air and moIsture from entering into the coating cause blIster defects. Of course, the putty knife technique sometimes affect the generation of the bubble, poor scratch technology Will be a larger amount of air enclosed in putty, so putty knife to master the correct technique.
11 The gas mixed into the coating material on the coating do not released while stirring, usually we recommend coating a curing agent and a diluent was added and sufficiently stirred and then allowed to stand for 5 minutes and then brought to 10 painting.
12 spray high ambient temperature, or air flow too quickly.
13 spray pressure Is too low or too high, the inter-channel flash drying time Is too short, after spraying warming too fast, or too close to a heat source paint.
14. The polyurethane coating with moIsture in air containing Isocyanate reaction to produce Carbon dioxide gas. Thus in the hot and humid environment in spraying, use of high solids coating thick coating, polyurethane coating Is easy to produce bubbles.
1. Construction in hot and humid climates, needs previously adding portion (not more than 5% of the total) in the high boiling solvent in the paint, can slow the speed of the film Is dry, the solvent in the coating volatilize sufficiently, to avoid excessive accumulation of the solvent. Strength while reducing volatilization, the coating surface Will not rapid cooling and temperature difference with the environment Is too large.
2. Pollution clean all surfaces are required, Will never allow the pro water remaining substances.
3. The grinding water to be frequently replaced, and all the dirt should be polIshed addition to the net, final rinse It should be deionized or dIstilled water. If you use tap water, you must use a clean and dry cloth, then dry.
4 has been wiped by hand to wipe the surface not above.
5. The air should be clean and not contaminated paint.
6. The spray primer or topcoat should have a suitable thickness.
7 between the layers should allow sufficient drying time, so that the intermediate solvent has sufficient volatile time.
8. After sufficient coating must be allowed to dry before exposure to moIsture and high temperatures in.
9. perennial large paint job case, it Is recommended to install effective freeze dryer. Drained daily air
seeking measures complement
with a needle prick the bubble, the bubble to determine the depth , and the reason for a low-power magnifier with the Isolated bubble generation. When the bubble generation between the paint layer, the defective area may be polIshed off, exposing the intact paint, then repainted. If the defect Is severe or the bubble generation time between the primer and the substrate, the substrate should be above all the paint off, then repainted. In fact, the bubble Is difficult to deal with the problem than to bite the bottom some extent more trouble, because there may be many times longer continuous coating Is still thIs problem occurs, the bubbles are generally destructive coating defects, it Is difficult reprocessing, in most cases can only be eradicated re-surface preparation, putty or spray primer.
relatively minor blIstering, prickly heat phenomenon, a method of treatment available: soap polIshed to smooth, two-component two primer closed, after drying paint practice two times re-spraying.
If the majority of the area of damage, and the depth deep primer layer or to the primer after decontamination should repaint the metal surface.