1, crust
It is stored in a container in vain, and the phenomenon of forming a patent leather on the liquid surface due to oxidative polymerization is called a crust. The reason is that the oxidative drying type coating has a large amount of over-polymerized tung oil coating due to too much driers, and the coating is not filled or leaked or the temperature is too high, and storage may occur for a long time.
2, thickening
The phenomenon that the viscosity of the coating increases during storage and becomes difficult to apply is called thickening. The reason is that the acid value of the coating is too high, and it is saponified with the alkaline pigment; the barrel is leaking. The solvent is volatilized; the water is mixed into the barrel or the pigment contains moisture; the storage temperature is too high to accelerate the polymerization of the paint; the storage temperature is too low, especially the water-based paint is susceptible to cold precipitation.
Precautionary measures; can be adjusted by adding dilution. If there is water, add proper amount of butanol. Stir well and adjust the viscosity. The latter can be stored in the greenhouse for 2-8 days to let it thaw.
3, precipitation agglomeration
In the paint, pigments, body pigments, etc., precipitated or a dense mass that is difficult to redisperse by stirring becomes a precipitated agglomerate, which may be caused by poor grinding of pigments or system pigments, poor dispersion or pigment and paint base. Physical and chemical reactions and other reasons. In the painting, remove the precipitate and grind it, add it to the original, mix well, filter and use.
4, sag
The phenomenon that the paint is applied on the vertical surface and the paint liquid flows downward is called sagging. The reason is that the paint is too thin, the viscosity is too low, the drying is too slow, the heavy pigment in the paint is too much or unevenly dispersed, the spraying distance is too close, the adhesion to the substrate is poor, the paint brush is too adhesive, and the paint film is too Thick, the temperature is too high during construction, so that the paint can be dried quickly without being leveled, etc., which are the cause of sag.
Precautions: Increase the viscosity of the application as appropriate, adjust the spray pressure and increase the spray distance appropriately. The thickness of one spray is controlled at around 30um to prevent and reduce sagging.
5, bite the bottom
The phenomenon that the upper layer paint softens and bites the coating film of the primer is called a bite bottom. Cause: The primer is not dry, the solvent of the top coat is too strong; the paint on the bottom is not matched.
Precautions: After the primer is dry or dry, apply a second coat. The solvent used in the second coat is matched with the primer.
6, slow drying and back tack
After the coating is applied, the phenomenon that the coating film does not dry or dry after the specified time is called slow drying and back viscosity. Cause: The solvent is poorly volatility, the primer is not dry, the top coat is applied; the construction temperature is too high, the temperature is too low, the surface treatment is not clean, oil and wax, turpentine, and the knot are not closed; In the case of chaotic impurities or leaking drier, etc., it is the cause of slow drying and back viscosity.
Precautions: Before painting, the surface should be free of oil, water, dust and other impurities. The coatings and thinners should be matched. If the relative temperature is too high or the temperature is too low, avoid coating. You can add appropriate moisture-proofing agent according to the construction environment. Two-component coatings should be formulated in strict proportion.
7, granulation
After the coating is applied, the phenomenon that the surface of the coating film is not smooth and fine particles are generated is called granulation. The reason is: the pigment is not finely polished during production, does not reach the specified fineness; or there is condensation during storage, the construction environment and tools are not clean; the paint and solvent do not match, and the speech produces microgel; the nozzle has small diameter and wind pressure Large, the spray distance is too large, the chaos in the feeding is mechanical impurities and not filtered, and the surface treatment is not clean. Prevention can take appropriate measures according to its causes.
8, whitish
The phenomenon that whitening or loss of light after the coating film is dried is called whitish. The main reason is that the construction humidity is too high (relative humidity >80%) and the solvent evaporates too quickly, causing the surface temperature of the coating film to drop sharply. The speech causes the water vapor to condense on the coating film, so that the resin or cellulose precipitates to cause whitening. Quick-drying volatile coatings (such as nitro, perchloroethylene, thermoplastic acrylic, etc.) contain a lot of low-boiling solvents and thinners to help whiten easily.
improve;
A tidal agent can be prevented by using a moisture agent and an appropriate amount of a high-boiling solvent (such as butanol) to adjust the solvent formulation, or to improve the construction environment, and to remove moisture from the compressed air. The shellac film is also whitish when it comes into contact with hot items (such as boiling water). It can be recovered by using cotton sputum alcohol or septic glue to smear it.
9, hair flower
When the multi-color paint is applied during the coating process or when it is dried into a film, some unevenness (such as yellowing, floating color, pan-gold, etc.) of the color and color of the coating film is called hair styling. This is mainly due to the difference in pigment density and particle size, poor lubricity of the pigment, large hygroscopicity, large oil absorption and partial dissolution of color (such as red powder). In this case, it is possible to add and replace the dry material. To improve the situation, an appropriate amount of protective rubber (ethyl cellulose, polyvinyl alcohol, etc.) or a lubricating oil (methyl silicone oil) can be added and improved.
10, wrinkles
In addition to the initial wrinkles, the phenomenon that the coating film shrinks sharply outside the dry many curved ridges is called wrinkles. If the drying is improperly applied or added too much, the coating film is not dry inside, the coating film is too thick, the outer layer of the current conjunctiva, the coating film is exposed to the sun or the baking temperature is too high, etc., which will cause the coating film to wrinkle. In this case, the replacement of dry materials can be used.
Improvements; improvement of construction conditions and other methods to solve, the alkyd resin material can be added a little amino resin to prevent wrinkles.
11, orange peel
Orange peel is the surface of the coating film forming many semi-circular such as orange peel. The reason is: the viscosity is too high when spraying, the pressure is too large, the caliber is too small, the spraying distance is too close, and the low boiling point solvent is too much when it is rapidly evaporated, so that the paint liquid does not reach the leveling and the orange peel is produced.
Improvement; select suitable solvent, construction viscosity, pressure, nozzle size, spraying distance should be appropriate, baking temperature should not be too fast, the surface of the coated object should be below 50 °C, the thickness of one construction is controlled at 20-30um.
12, shrinkage
After the application of the paint, the surface of the coating film shrinks, as if the water is applied to the wax paper, and the phenomenon of exposing the primer is called shrinkage, also called "laughing" and "pitting". Mainly due to the poor lubricity of the coating on the surface of the coated object, so that it can not form a uniform coating film, and shrink into a bead shape; the surface is too smooth, the primer gloss is too large, the object surface is stained with oil or smoke Smoked; the spray equipment is mixed with oil or moisture; the solvent evaporates too quickly, the coating film is too late to level; the spray density is too high, splashing paint, etc., will cause the film shrinkage.
Shrinkage is common in varnishes, red lacquers, polyurethane coatings, epoxy coatings, and pure phenolic coatings. Adding appropriate additives can improve the shrinkage of the coating.
13, pinhole
The dried surface of the coating exhibits a needle-like aperture called a pinhole. Cause: Drying is too fast, the coated object quickly enters the high temperature baking, the bottom layer is painted without dryness, the construction viscosity is too high, the surface treatment is not clean and contains oil, water, dust and other impurities. Precautions: Strictly dry according to the drying temperature and time specified in the coating process. When drying, it should gradually enter the high temperature zone from the low temperature zone. According to the spraying method, the appropriate coating viscosity should be adjusted. The thickness of one spray should not be too thick. The pretreatment should be clean and free of impurities. Do not let the oil, water, dust and other impurities be mixed into the paint or solvent, and the existing pinholes can be remedied by scraping the putty.
14, foaming
The phenomenon of small round vesicles on the surface of the coating film is called foaming. The main reason for this morbidity is that it is baked at a high temperature immediately after painting. When the bottom layer is not dry, the topcoat is applied, the construction viscosity is too high, and the surface treatment is not clean. It contains impurities such as oil, water and dust.
Precautions: Strictly dry according to the drying temperature and time specified in the coating process. When drying, it should gradually enter the high temperature zone from the low temperature zone. According to the spraying method, the appropriate coating viscosity should be adjusted. The thickness of one spray should not be too thick. The pretreatment should be clean and free of impurities. Do not let the oil, water, dust and other impurities be mixed into the paint or solvent. The paint and solvent used should be matched.
15, the bottom
After the paint is dried and formed into a film, the color paint can not cover the color of the substrate, and the phenomenon that the coating is obviously too thin is called the bottom. The main reason is that the pigment in the paint is not enough or the hiding power is too poor; too much thinner is added during the construction; the paint liquid is not evenly stirred, and the coating is too thin.
Improve; select the pigment with strong hiding power, stir well even when used, the viscosity of the construction is properly adjusted, and the coating thickness is controlled at 20-30UM.
16, bleed
The topcoat dissolves the primer so that the color of the primer penetrates into the surface, which is called bleed, also known as biting. This phenomenon often occurs when applying a light paint to a red primer or asphalt. Mainly the primer is not dry, the topcoat dissolves the primer paint film; the primer contains the dye, and the asphalt without the seal layer will appear bleeding after the top coat.
Precautionary measures; use the thinner of each coating material to be matched. After the bottom layer is dried, apply two layers. The color of the middle layer and the surface layer should not be too different.
17, loss of light
The phenomenon that the gloss slowly disappears after a short period of time (hours or days) after the coating is dried and formed into a film is called loss of light. The outdoor paint film does not belong to this phenomenon after long-term exposure to light. The main reason is that the oil and resin are insufficient or incompatible with each other and the polymerization degree is improper; the amount of the diluent is too much; the weather is cold or high temperature; after the baking paint is applied, the diluent does not reach a certain level and enters the drying room; After the encounter with atmospheric smoke; the surface treatment is not or the primer is not dry.
Precautionary measures; select each coating material thinner to be matched; strictly follow the drying temperature and time specified in the coating process for drying, when drying should be changed from low temperature to high temperature; grinding time should use appropriate abrasive cloth and grinding disc, after grinding Dust should be cleaned; pre-treatment should be free of oil, embroidery, water and dust impurities.
18, powdered off
After the paint film is dried, the surface color is dull and dull, and the phenomenon of sticking to the hand by hand is called pulverization. The main reason is; the surface treatment is not clean, there are oil, water, and other contaminants; the drying stability is too high or quickly enters the high temperature baking, the primer is not dry coated with the topcoat; the diluent is not used; the coating is coated with a large viscosity. The layer is too thick; the viscosity of the coating is too low and too thin; it is not resistant to high temperature baking and the coating is zoomed and pulverized.
Precautionary measures; pre-treatment should be completely free of oil, water and dust impurities, according to the material of the workpiece, thickness, size, shape, drying performance, heat source, temperature control, accuracy, drying temperature and time.
19, crack
The surface of the coating film appears to be different in depth and depth, just like a crack in a turtle. If the coating film is cracked for a long time, this is a natural aging process of the film, indicating that the film failure requires recoating and is not morbid. Mainly because the primer is not matched, the coating film is caused by external stress (mechanical action, temperature change, etc.), and if the short oily alkyd topcoat is easy to crack on the long oil alkyd primer. In addition, the selection of coating varieties is not matched, and epoxy or modified phenolic and asphalt are used for outdoor coating and metal surface primer for wood. The volatilization in the coating is too much, the adhesion is poor, the dry pigment or the drier is too much, and the old coating is continuously repaired. The number of top coat layers is too large, the coating film is too thick, the construction environment is bad, and the coating is not When the pigment is thoroughly stirred, it is easy to cause cracking.
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