Technical backstopping

       ASTM F963/EN71 Part3

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Coating
A collective term used to represent liquid or solid materials that are applied on the surface of an object to achieve the purpose of protection, decoration or other special purposes (insulation, anti-corrosion, markings, etc).
Organic coating
Main substance that constitutes the film is made up of organic materials Inorganic coating
Inorganic coating
Main substance that constitutes the film is made up of inorganic materials
Paint
Coatings that contain colouring pigments. When applied to a substrate, it can form a film that achieves the purpose of protection, decoration or other special purposes.
Putty, filler
Paste-like-coating which is used to eliminate small dents on the surface of a substrate.
Primer
When coatings are applied in many layers, it is to be directly applied on the surface of the substrate.
Finish, top coat
Paint or varnish that is applied as the last layer when many layers of coatings are applied.
Varnish
Coating which does not contain colouring pigments. When applied on a substrate, it forms a layer of transparent film that achieves the purpose of protection, decoration or other special purposes.
Colored varnish
Transparent coating containing colored pigments
Solvent based coating
Coatings that has an organic solvent base
Water (based) paint, water based coating
Coating using water as the only or main medium
Powder coating
Powder-like coating which does not contain a solvent
Two-component coating, two-pack coating
Coating which requires the mixing of two components according specific ratios before usage
Medium, vehicle
Normally refers to the liquefied component in paints
Binder
Non-volatile component of coating. It can form coating films and coagulate color pigments.
Film former, forming material
A special material that is able to form a continuous film that has a certain degree of hardness by itself Resin
Resin
A solid, semi-solid. or pseudo-solid polymer which does not have a fixed molecular weight. It can sometimes be a liquid polymer. It changes its state according to a temperature range. During its softened stage, stress will cause it to flow.
Plasticizer
A substance that is able to enhance the flexibility of a coating film.
Solvent
Substance that evaporates under dry conditions; a one component or polycomponent liquid that can completely dissolve a coating base.
Co-solvent
Substance that evaporates under dry conditions; it does not dissolve coatings by itself, but when mixed with solvents in an appropriate ratio, it can enhance the dissolving power of the solvent.
Thinner
A one component or polycomponent volatile liquid. When added to coatings, viscosity is reduced.
Pigment
Usually in powder form; a colored substance that does not dissolve in a medium. It is widely used in coatings due to its optical, protecting, and decorating ability
Inorganic pigment
A type of pigment that contains inorganic chemical components
Organic pigment
A type of pigment that contains organic chemical components
Extender, filler
Substance that usually appears white or slightly colored. It is a type of pigment having a refractive power of less than 1.7. Widely used in coatings due to its chemical or physical properties.
Dye-stuff
A colored solvent that dissolves in a medium; It is either natural or synthetic. It provides colors to coatings.
Drier
An organic metal compound that can usually be dissolved in organic solvents or coating bases. When added moderately to oxidized drying coatings, it can speed up the drying process.
Substrate
Various types of material which coatings can be applied on; this refers mainly to the surface of the material.
Coat
A continuous film which is obtained from painting the coatings once
Film, paint film
Continuous layers formed on the substrate after applying the coatings
Drying
A process where a liquid film is transformed to a solid film.
Air drying
A natural drying process where room temperature is used to dry a film.
Baking, stoving
A process where heat is used to dry a film.

Reasons for abnormal condition	Methods for prevention and cure
Opacity 1. Water contents are present in solvents (benzene, petroleum, turpentine, acetone, alcohol, etc.). It is caused by water present in containers, or containers with loose covers exposed to rain. 2. Storing varnish with drier (especially drying agents with lead content) under humid or low temperature conditions. 3. Inappropriate methods of using diluents. Excessive amounts will make varnish appear gel-like. If dilution is not carried out properly, part of the film would not be dissolved. 4. Mixing two different types of varnish.	1. Covers of containers must be tight and containers should not be put outdoors to prevent water from entering. 2.If solvents contain water, benzene, or petroleum, acetone should be put at a separate level. 3. Heating in a water bath (65℃) can eliminate the problem. Storage room temperature should be kept at 20℃. 4. Avoid mixing of varnishes.
Precipitation 1. High density color pigments, big particles, high filler content, low viscosity of coatings, or grinds that are not evenly spread out. 2.Putting too much diluent lowers the viscosity of the coatings. Long storage time would also cause this problem.	1.Putting containers horizontally or upside down from time to time, applying first-in-first-out principle. 2.If possible, taking out the large precipitation, disintegrating it into smaller particles, and putting them back to the original container. Stir properly and filter the coatings before using.
Skinning 1.Container not fully filled or not airtight, air in the container, having too much poly tung oil in the coatings 2.Coatings are too thick, pigment content and cobalt drier content is too high. The longer the storage period, the thicker the skin.	1.Containers should be airtight, if not, replace them with new containers. Coatings with high viscosity should be used first. 2.Remove the skin, pour same type of diluents after use, cover the container tightly. Besides, when there are not much coating left in the container, do not use the original container, use a smaller one instead. Cover the surface of the coatings with vanguard sheet to minimize wastage due to skinning.
Changing colors 1.When shellac varnish is stored in iron tins, the color will be intensified. The longer it is stored, the more intense the color, and it may be more difficult to dry. 2.Reaction occurs between varnish and gold dust or silver dust (Corrosion). This causes the coatings to lose its gloss, becoming green and dark. 3.Different densities of pigments in multi-colored coatings will cause this problem. High density pigments sink while lighter ones float.	1.Metal containers cannot be used to store shellac varnish. Non-metal containers (ceramics and glasses etc.) should be used instead. 2.Color pigments such as gold dust and silver dust should be packaged separately from coatings. They should be mixed only when they would be used immediately. 3.Mix thoroughly before using.
Swelling 1.Livering: A process whereby oxides such as red lead is reacted with natural rubber in coatings. 2.Gelatinization: A process caused by over-concentration of coatings. Polymerized colloid increases viscosity and becomes gels. When color pigments such as iron blue meet with coatings with high degree of polymerization, gels would be formed. 3.Thickening: Also known as thixotropy, a phenomenon where coatings appear thick, but is able to flow after stirring with machines. Once stirring is stopped, it regains its high viscosity. It usually appears on coatings with high color pigment content such as talcum powder, lithopone oxide and red lead powder. Usually, it is difficult to get rid of the brush marks as well.	1.Mixing varnish and red lead powder only during usage. 2.Such a process is a physical change and is temporary after stirring with machines. The problem can be solved by adding anti-coagulation liquid. 3.Actually this phenomenon is not an abnormal condition for coatings (other than the brush mark). In contrast, it is a merit point. It prevents runs which cause uneven layers after applying coatings, and at the same time, it prevents settling of color pigments.

Reasons for abnormal condition	Prevention and cure
Unable to dry or unable to adhere to the substrate Inappropriate oil plant content in coatings, inappropriate warming process, inappropriate resin contents or insufficient drier.	Poor quality coatings should be exchanged. If the problem is caused by insufficient drier, drier can be added to solve the problem.
Settling 1.Such phenomenon is caused by high density pigments, pigments with large particles, too much filling, low viscosity of coatings, and grinds that are not evenly spread out. 2.Adding too much diluent lowers the viscosity of coatings. Besides, storing the coatings for too long causes the same problem.	1.Putting containers horizontally or upside down from time to time, applying first-in-first-out principle. 2.If possible, take out the large precipitation, disintegrate it into smaller particles and put them back to the original container. Stir properly and filter the coatings before using.
Rising of particles Occurs when manufacturing process of coatings is not controlled strictly, pigments are not grinded sufficiently, or containers are not clean enough.	When using coatings, stir thoroughly and filter properly.
"Orange skins" and "wrinkles" A phenomenon where oil contents in coatings do not aggregate properly, solvent is inappropriately used, or when coatings have too high viscosity etc.	Coatings with poor quality should be replaced. Test coating films before actual operation, and adjust viscosity of coatings
Losing gloss Poor quality solvents in the coatings, too few film forming matters, and too much solvents can cause the surface of coatings to dry too fast and lose gloss.	Mixing same kind of coatings to adjust viscosity or adding varnish to improve its gloss.
Whitening A phenomenon caused by whitening of lacquer in humid weather, or inappropriate usage of solvent.	Warm the substrate slightly before applying coatings, and add 10%-20% of desiccant.
Mismatch of colors Color of coatings deviates from the standard. The difference in tone of color cannot be solved by thorough stirring.	Remix with same type of coatings.

Reasons for abnormal condition	Prevention and cure
Separation 1.Mistake of using benzene solvent with lacquer. 2.Using petroleum solvent on epoxy-ester coatings. 3.Shellac varnish absorbs water; evaporation of alcohol will cause separation as well.	1.Adding ester solvent to solve the problem. 2.Use methylbenzene or dimethylbenzene as solvent. 3.Separate water from shellac varnish, add alcohol and stir thoroughly. Seal up after usage.
Seediness 1.Unclean operation condition, causing dusts to fall on the surface of coatings. 2.Unclean tools used during application of coatings. Dusts or dry coatings’ skins in brushes would come out during brushing. 3.Coatings’ skins are mixed into coatings, causing seeds to appear on the surface. 4.Unclean spray guns or using spray guns that were previously used for oil-based coatings for Lacquer. Solvents would bring up the coatings’ skins that are mixed into the coatings.	1.Clean the place before applying coatings and wipe the tools thoroughly as well. 2.Check the brushes for foreign matters before using them to paint. Scratch off the impurities and use petroleum to wash the brushes. 3.Scratch off coatings’ skins carefully and filter the coatings. 4.Use separate spray guns for lacquer varnish. If using spray guns that were previously used for oil-based coatings for lacquer, wash thoroughly before using.
Runs, sags, curtains 1.When brushing, the brushes are dipped too deep into the coatings and the paint is not spread out evenly. Brushes are too soft when the coatings are too thick to be spread out. The brushes are too short when the coatings are too diluted. 2.When spraying, the coatings are too diluted. The mouth of the spraying gun is too wide or the pressure of the gun is too small. The spraying gun is held too near to the object, the speed of spraying is too slow. 3.Coatings with too high viscosity would cause runs. Objects with troughs or ditches would form sags easily. 4.Substrates with rough or complicated surface would form sags easily. 5.Operating under low temperature and humid condition that slow the drying process.	1.Do not dip too much coating on brushes each time. Use soft brushes when applying diluted coatings. Use short brushes when the coatings are thick. Coatings should be evenly spread out with appropriate thickness. 2.Coatings should have appropriate viscosity. The mouth of spray guns should be wide with appropriate pressure of 0.4-0.5 Pa for lacquer. Spray guns should be approximately 25 cm away from the objects. Mouth of spray guns should be smaller for oil-based coatings. Spray guns should be at least 30 cm away from the objects. Oil-based coatings and oven-dry coatings cannot be sprayed in multi-layers, thus the speed of spaying should be fast. 3.Dip coatings should have a viscosity of 18-20 seconds. After application, place the object on filter nets for 20 minutes, or use centrifugal apparatus to remove residual coatings from troughs and ditches. 4.Use brushes of appropriate length and texture. 5.Under undesirable conditions, drier should be added to speed up drying process. Preferably, drying test should be conducted before operation.
Slow drying process and separation 1.Unclean substrates, and pollutants such as wax, oil, salt and alkaline materials are found on the substrate. 2.Coatings films are too thick, causing the oxidation process to be restricted to the surface. Inner layers thus could not be dried. For example, thick layers of coatings made up of linseed oil take years to dry in shadows. 3.Pollutants from air such as sulphide and nitride are present on the older layers of coatings. As a result, when normal coatings are applied, they cannot be dried fast or are unable to be dried at all. Such a condition is especially prevalent on kitchen widows and doors. When substrates are left for too long after applying first layer, it becomes harder to dry. 4.In poorly ventilated space in humid and cold weather, oxidation process would be slowed down. Thus, the prolonged drying process causes separation of coatings from substrates.	1.Metal surface should be treated carefully before applying coatings. After removing solid pine resins from wooden material, shellac varnish should be used to seal it. 2.Coatings should have appropriate viscosity. Do not apply new layers before the previous layers are dry. Use suitable coatings under different conditions. 3.Substrates with old coatings should be polished and cleaned properly. If substrates are contaminated by air, they should be washed with lime water (50kg water with 3-4kg lime). For parts that are dirty, use brushes to wash repeatedly. If a base layer is going to be applied, wash the substrate with petroleum. 4.If the weather is cold, do not apply coatings hastily. Drier should be added. Stir well and conduct drying test on the coatings. If the result is not desirable, adjust level of drier used. Apply the coatings only when testing results are desirable.
Pin-holes 1.After applying the coatings and between the process of evaporation of solvents and the stage of forming films, the solvent evaporates rapidly, especially when it is heated in ovens. Films are unable to fill up the empty spaces. Thus, pin-holes are formed. 2.Solvent is not applied appropriately, or the temperature is too high. For example, if petroleum is used as solvent for asphalt paint, pin-holes would be formed. The effect would even be more serious after heating in ovens. Filler or base layer is not smooth enough. As a result, pin-holes occur on the outer layers. The effect is even more intense if spraying lacquer. 3.Operation is not being carried out carefully. 4.Operation environment has high humidity, or malfunctioning of oil-water-separation device will create pin-holes by spraying water together with coatings at the same time.	1. Oven-dry coatings should have appropriate viscosity. After application, objects should be placed in room temperature for 15 minutes. When heating in ovens, one should start from low temperature for 30 minutes, and then adjust to appropriate temperature as required to evaporate the solvent. 2.Turpentine should be used to dilute asphalt paint. After application, leave the object for 15 minutes. During heating, start from low temperature for 30 minutes, and then control temperature and time appropriately. 3.Plastic surface should be smooth. When applying base layer, brushing method should be used instead of spraying method. Brushing method enables pin-holes to be filled. When the base layer becomes smooth, extra layers can be sprayed on. 4.When spraying coatings, the environment should have a humidity level of lower than 70%. One should check the reliability of oil-water separation device before using. Compressed air must be filtered, oil, water, or other impurities should not be brought into coatings.
Bleeding 1.When spraying lacquer, solvent has high penetrating power; coatings from inner layers can penetrate to the outer layers, causing contamination of colors on the outer layers. 2.When applying coatings, dying agent is present on wooden material. 3.When applying light colors on red base, red color could mix with other colors. For example, white coatings would become pink, yellow coatings would become orange.	1.Stop application of the coatings once bleeding occurs during spraying. Dry the substrates with coatings, sanding them and apply shellac varnish to quarantine them. 2.Apply one layer of shellac varnish to quarantine the dying agent, or change to coatings with appropriate colors. 3.Change coatings with lighter colors if the outer layer is red or use shellac varnish to seal the base layer.
Whitening 1.When humidity in air reaches 80%, solvent in volatile coatings evaporates, lowering the surrounding temperature of the substrate. As a result, water moisture starts to condense on coatings film. Water moisture would also condense in spraying equipment; water is thus brought to coatings when spraying. 2.Thin steel boards have lower heat capacities than thick steel boards. Thus, applying volatile coatings on thin steel boards during winter would cause whitening on the coatings film. 3.Inappropriate usage of solvents. Diluents with low boiling points are too high in proportion, or water exists in diluents.	1.When spraying volatile coatings, choose weather with low humidity. If it is an emergency usage, apply heat on the substrate with low temperature before applying, or add suitable amount of desiccant to prevent moisture. Remove condensed water in spraying equipment and check the reliability of oil-water separation device. 2.Apply heat on the steel board with low temperature before spraying. If the steel board is not removable, use flame to heat it. 3.Desiccant should be added to diluents with low boiling point, or exchange diluents with water content.
Blistering 1.Iron rust, grease, and other types of pollutants are found on the substrate. If base coatings are applied without proper cleaning, blistering occurs. 2.Non-drying oil penetrates into surface of wooden substrates. Blistering or even peeling would occur after application of coatings. 3.When coatings are applied on humid walls, water moisture on the wall would expand, causing blistering or even peeling off of coatings. 4.When coatings are applied on wet wooden substrates, water starts to evaporate in hot weather and pushes the film, forming blisters. If the situation is not controlled, peeling of coatings may occur. 5.Apply mastics when the base layer or the inner mastic layer is not dry totally. Hence, coatings or mastics in inner layers are sealed, only the outer layers can be dried. 6.Layers of shrivel finish are too thick, solvent thus cannot be evaporated. The substrate is put into the oven too early at too high temperatures. 7.Rusts on the substrates are not cleaned thoroughly; gas is produced during heating in ovens. 8.When washing aluminum-plated substrates, cleaning liquid is left on the substrates. 9.Water exists on air compressor and pipes. As a result, blisters are formed on the outer layer. Spraying coatings on wet mastic layers causes blisters as well.	1.Rusts, oxidized skins and oil pollutants on metals, grease, and wax on base layers should be cleansed thoroughly. 2.Wooden materials should be washed repeatedly with hot sodium hydroxide to remove oily substance. Then wash away the solvent with hot water. 3.Wait for concrete walls to dry completely before applying coatings. 4.Use dry wooden materials or wait for wooden substrates to dry completely before applying coatings. 5.Do not apply extra layers of coatings if the inner layers are not dried completely. Remove existing blisters, patch them with mastics, and repaint the substrate. 6.Coatings should have appropriate thickness. Solvent should be evaporated completely before putting into ovens. Temperature in the ovens should be raised gradually according to guidelines. 7.Rusts on the surface of the substrates should be cleansed thoroughly. 8.Heat the substrates in ovens with temperature of 200℃ for 1-1.5 hours. Leave them to cool down to room temperature before applying coatings. 9.Mastic and base layers should be dry completely. If oil-water separation device is used, ensure the condensed water is removed.
Shrinking 1.If diluted coatings are applied on smooth coatings’ surface, shrinking occurs just as when water is put on glasses. 2.Diesel or wax is present on wooden surface. If coatings are applied on waxed surface, not only would shrinking occur, the coatings would not be dry. 3.Unclean oil on metal substrates penetrates into mastic layers. When base coatings are applied, oil is mixed with the base coatings. After first layer of oven-dry coatings becomes dry, speed of evaporation of solvent cannot catch up with speed of drying during application of second layer.	1.Before applying the coatings, use sand paper to remove the gloss on the surface. Use coatings of appropriate concentration. 2.Apply gypsum powder repeatedly on wooden surface with diesel. Remove wax on the wooden surface and clean it with butanol. 3.Surface of the substrate must be clean. Oil on mastic layer can be washed with dimethylbenzene and calcined gypsum, or parts with oil can be removed and patched with mastic. 4.Use suitable solvent with appropriate solubility. Use low temperature during heating to allow evaporation of solvent. Then monitor the temperature and time according to types of coatings used and technical condition.
Haziness 1.When center blue hydroxyl-acid enamel is mixed with white phenol aldehyde paint. Piebald occurs even with proper stirring. The effect is even more obvious with brushing. 2.Multi-color coatings such as grey or green coatings; color pigments with higher density would sink while color pigments with lower density would float. If such coatings are not stirred properly, color tones would not be even. 3.Brushes are not cleaned after using them for dark color coatings. When such brushes are used for light color coatings, the previous dark color coatings appear.	1.While using center blue hydroxyl-acid enamel with white phenol aldehyde paint, one must stir the coatings thoroughly from the bottom. 2.Be cautious when using coatings containing color pigments with different densities. Stir thoroughly before using. 3.Wash brushes which are used for dark color paintings.
Lifting 1.Lifting can be caused by different film forming matters. For example, when lacquer is added to alcoholic acid coatings or grease based coatings, the strong solvent would permeate and cause expansion of coatings film. 2.Lifting can be caused by similar film forming matters. For example, when epoxy resin varnish or epoxy insulation varnish (air dry) become dry, lifting occurs when second layer is applied. 3.If phenol aldehyde antirust is used on press forging, and when lacquer or perchloroethylene coatings are added after drying process, lifting may occur.	1.Same type of coatings should be used for enamel coatings. Iron red alcoholic acid coatings can be added to separate the layers after sanding. 2.When applying second layer of epoxy resin varnish or insulation coatings, it should be added after the first layer becomes dry. In addition, under normal circumstances, one thick layer of epoxy resin varnish is sufficient. 3.Scratch off phenol aldehyde antirust completely. Apply a base layer of iron red alcoholic acid coatings before applying lacquer or perchloroethylene coatings.
Decorative pattern that does not appear 1.Layers of shrivel finish is too thin or the coatings are too diluted. Failing to use special diluents for shrivel finish. 2.Oil on the substrates is not cleansed completely, temperature is too low, heating time is insufficient, or shrivel finish fails to show effect. 3.When spraying hammer paint, pressure is too high. Thus decorative patterns are not obvious or cannot be shown. 4.After spraying first layer of hammer paint, the substrate is left for too long. When second layer is applied, the decorative patterns are not obvious or cannot be seen at all. 5.Mouth of spray gun used for hammer paint is too small. The decorative patterns would thus be small or unable to be seen.	1.Shrivel finish should have appropriate viscosity. Coatings should be sprayed with appropriate thickness. Use specialized diluents for shrivel finish. 2.Oven temperature should be above 80℃ for shrivel finish. Decorative patterns should be shown after 30 minutes. Oven temperature should be at 110℃ for dark color coatings. 3.When hammer paint is sprayed on medium to small-sized objects, the pressure should be at around 0.3Pa. 4.After applying the first layer, the substrate should be left for 10 minutes during summer and 20 minutes during winter before spraying the second layer. 5.Caliber of mouth of spray guns should be at 2.5mm for medium to small-sized objects. For big objects, caliber can be at 3mm.

Type of problem	Causes	Solution
Strength of spray is too vigorous, producing strong fog of coatings	1.Spraying pressure is too strong 2.Outflow of coatings is not sufficient	1.Adjust the pressure reducing device on oil-water separation device to reduce pressure 2.Loosen the screw that restricts movement of the trigger of spray gun to increase outflow of coatings
Insufficient outflow of coatings, spray gun stops functioning	1.Insufficient air pressure in the pipe 2.The switch which controls the air intake to the oil-water separation device is not fully open 3.Air leaks in spraying system 4.Pressure in the coatings supply container is too high.	1.Raise air pressure 2.Fully open the switch, straighten the air pressure pipe 3.Check the joints and switches in the system 4.Adjust pressure reducing device, reduce pressure in the coatings supply container.
Discontinuous spraying	1.Mouth of spray gun is blocked 2.Insufficient coatings 3.Pipes which deliver coatings are twisted, or the switch is turned offs	1.Use solvent to wash the mouth of the spray gun 2.Add coatings to the coatings storage container 3.Correct the position of the pipe, open the switch, check for spoiling parts
Density of spray is uneven or coatings flow out sideways	1.Round-shaped holes which are used for air passage is blocked 2.The screw on the spraying part is not tight, center of the spray head is not at the correct position.	1.Clean the mouth of the spray gun and use solvent to wash the air passage. 2.Tighten the screw on the spraying part, check and reposition the centre of spray head
Foams are produced during spraying	Thimble is not adjusted. It is not over the open air passage.	Take out the sealing pipe that contains the thimble. Adjust the nut at the end of the thimble. This allows the passage to be opened first before the thimble is moved away while the trigger is pushed.
While the spray is adjusted to flat shape, round shaped spray continues to come out	The air passage of the two air holes at the side of the spray head is blocked	Remove the spray head, use solvent to wash the air passage at the side.
The air passage of the air holes at the sides of the spray head is blocked. When the trigger is released, spray gun continues to spray coatings	Pedestal is pushed too tightly	Unscrew the head of the pedestal, lubricate the pedestal and adjust its tightness
Coatings dripping out from the mouth of the spray gun while the spray gun is not used	The mouth of the spray is blocked. Thus the thimble fails to seal the spray head	Remove the spray head, unscrew the mouth of the spray gun and wash it
Coatings permeate out from the spray head	Mouth of the spray gun is not tight. The tip of the mouth is spoiled	Remove the thimble and seal the pipe. Adjust the screw head of the thimble. This allows the screw head to be near the end of the thimble. Screw the mouth tightly or change to a new mouth piece
Coatings dripping from the trigger	Wear and tear of from pedestal	Change a new pedestal
Air leaks out from the mouth of the gun when it is not used	Air passage of the spray gun is blocked	Remove the thimble and seal the pipe. Use brushes to wash clean, and use soft clothes to clean the socket and cone off the valve
Air leaks from the side of the hand	Wear and tear of the back pedestal or back pedestal is too loose	Tighten the cover of the pedestal. If the problem persists, change the sealing filler.

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Types of problem	Causes	Solution
Poor adhesion power	1.Mold releasing agent exists on the surface of the substrate 2.Water, oil, etc are found in the compressed air 3.Oil is found on the hands of the deliverers or operators	1.Do not use mold releasing agent on the substrate 2.Remove oil and water from the compressor periodically; install oil-water separation device 3.Operator should wear protecting gloves
Plastic surface is being corroded	1.The solvents in the coatings are too strong 2.The plastic object has uneven density 3.Resin is not polymerized properly in the plastic	1.Adjust the composition of the diluents. For example, butanol can be added. 2.Improve the quality of the substrate, for example, adjust the temperature and time of molding 3.Choose resin wisely from different production places and types
Poor smoothness on the surface of the coatings film	1.Coatings have high viscosity 2.Drying speed is too fast 3.Diluents evaporate too fast	1.Adjust the viscosity of the coatings 2.Raise temperature slowly on the drying flow-line 3.Add solvent with high boiling points into the diluents
Whitening occurs on the film	1.Operation environment has high humidity 2.Solvent evaporates too fast 3.Diluents with high boiling points has poor solubility	1.Lower humidity in the operation environment or heat up the substrate 2.Add diluents with strong solubility that evaporates slowlys 3.Change to diluents with high boiling points
Color and gloss is uneven on the coatings film	1.Inappropriate choice of resin in coatings 2. Drying process is too fast under heating 3.Operation environment has high humidity	1.Reuse coatings 2.Raise temperature slowly from low to high. 3.Improving molding technique of the plastic 4.Adjust humidity level of the operation environment
Coatings have insufficient hardness	1.Coatings are not dried completely 2.Coatings film are too thick 3.Migration of plasticizer of the plastic 4.High-boiling-point cannot be released	1.Raise efficiency of drying process 2.Choose small spray guns. Control the thickness of the coatings film to 15-25 micrometer 3.Use coatings with better hardness 4.Adjust the composition of the solvent