January 18, 2023 Longchang Chemical

Must collect the 61 common sense paint!

1、Why is it best to use primer for the bottom filling in the painting process?

A: Because primer is designed to fill in the main purpose of the formula, it has excellent filling and sanding properties, and low cost, while if the top coat is used to fill in the bottom layer, the filling effect is poor, and the cost is high.


2、Why not use transparent putty to fill the wood eye in the bottom coloring process?

A: Before staining, the use of transparent putty will make the board not stained. If the transparent putty is used after coloring, it will affect the uniformity of coloring due to the uneven thickness of the putty coatingol.com.


3、What is the difference between primer and bottom paint?

A: The permeability of Bottom Depot is better than primer, after the film is formed, the closure between Bottom Depot and wood fiber, the coating film is more dense than primer. The sealing effect is better.


4、Why should the primer be thoroughly sanded and smoothed before applying the top coat?

A: 1、To enhance its adhesion;

2, the top coat has a strong with the trap, such as the primer is not flat, the top coat is coated, the film effect is poor flatness.


5、What are the criteria for thorough sanding of the primer?

A: 1, 450 angle to see no bright spot;

2, is hairy glass shape.


6、What is the standard for the number of times of primer application?

A: The wood eye should be filled thoroughly. That is, by sanding can get a flat paint film effect.


7、Why PU paint emphasizes the main paint, curing agent, thinner supporting the use?

A: Different PU paints have different dilution systems and different solid content. If the use of mismatched diluent or curing agent, it will affect the cross-linking reaction of the paint, resulting in insufficient hardness, not dry, film cracking and other problems.


8、PU paint in the deployment, why emphasize the proportion according to the requirements of the proportion?

A: The ratio of PU paint and curing agent is calculated through the chemical reaction molecular formula. The ratio should be strictly controlled. If you add more curing agent, the paint film is easy to brittle burst. Construction is easy to produce bubbles, matte gloss is high. If you add less curing agent paint film hardness is not enough, scratch resistance is poor, slow dry or even not dry.


9、Why can’t I use color essence for color mixing?

A: Because the composition of color in solid color paint is mainly pigment. And color essence is composed of dye, no covering power. If the color essence is used in the real color paint, the color tone is not obvious, and it is easy to produce floating color, so the color master batch is used in the real color paint.


10、Why do I need to stir the paint fully when constructing?

A: Paint is a mixture of resin, pigment, solvent, etc. It is not a solution. It is not a solution. The pigments in it, the matte powder in matte paint, etc. are dispersed in the paint solution. Therefore, there is usually some degree of sinking during the storage process, forming the usual paint layering. Therefore, it is necessary to stir the paint well before mixing. (The paints that must be stirred are: matte paint, transparent tinted surface, solid color paint, wood grain treasure.)


11、How to see the yellowing resistance of paint?

A: Paint yellowing is a characteristic of paint, not a pathology. Therefore, the yellowing of paint is relative not absolute, PU paint, general yellowing resistance and yellowing resistant paint, usually light-colored panels choose yellowing resistance, dark panels choose general yellowing resistant paint


12、How does the moisture content of wood affect the quality of the finish?

A: Undried wood contains a lot of water, in low temperature, high humidity, wood absorption of moisture in the air and expansion, and high temperature, low humidity, the moisture in the wood gradually evaporated outward and shrinkage, but the wood in all directions of shrinkage and expansion rate is different. The longitudinal direction is the smallest, the radial direction is larger, and the chord direction is the largest. When the surrounding air state changes, wood moisture content is also followed by changes, causing wood expansion or contraction. The general moisture content of wood should be controlled at 8-12% as appropriate. If the moisture content exceeds the controlled moisture content, the wood of the furniture appears moist, coating dry slowly when painted, will reduce the adhesion of the paint film, will make the volatile type such as nitrocellulose paint flooding white. It will make the curing and drying type of paint, such as PU paint produce bubbles, pinholes and other defects in the paint film. In a dry climate, the wood contains water evaporation and shrinkage, easy to produce cracks, so that the surface of the paint film damage, therefore, do furniture wood must be dried, moisture content should be controlled within the specified range. In addition, the wood white blank in the primer before doing must be effective closure, such as the use of China Resources PS900 bottom to prevent the wood in the water and other substances to spread outward, to help prevent wood deformation, paint film blistering, pinholes and other phenomena. It also helps to remove the wood hair after drying sanding and other effects.


13、Why does the paint film of spraying nitrocellulose paint (NC) turn white and how to prevent it from turning white?

A: The phenomenon that the paint film is cloudy or milky white after the film is formed is called paint film whitening, also called whitening, whitening, whitening, etc. Nitrocellulose paint spraying film whitening of the original trapped analysis is as follows.

1, nitrocellulose paint itself has a very good solvent release, solvent evaporation in NC paint to the atmosphere, it is easier than in other paint;

2, NC paint formulations contain more solvents that evaporate faster;

3、In case of high temperature environment, the solvent will evaporate faster;

4、The rapid evaporation of solvent absorbs the internal energy of the wet film of NC paint film, which makes the surface temperature of the wet film drop 2-30C instantly and provides a “cold bed” for “condensation” to occur;

5, high temperature and high humidity environment, so that the wet film around the high content of water vapor quickly in the “cold bed” condensation into micro-water beads;

6, micro water beads and wet film of bad miscibility, resulting in cloudy or milky phenomenon, called “whitening”.

The above 1, 2, 3 is the prerequisite of whitening, 4 is the intermediate process, 6 is the final result. After the occurrence of whitening phenomenon, some appropriate temperature (such as shining with a lamp) can make the whitening disappear and restore as before. Some are irreversible and forever white, the reason is not known. Although there are estimates, but do not repeat.


14、The following measures can be taken to prevent “whitening” of paint film.

1、The temperature of the painting environment should be 15-250C, and the relative humidity of the environment should be no more than 75%;

2、Check the effect of oil and water separator frequently when spraying, and remove the water in compressed air in time;

3, we should pay attention to try to take the higher quality of paint and Tenar water;

4, when the high temperature, high humidity environment, the construction of the phenomenon of whitening, you can add white water (such as China Resources furniture paint Nz308 white water), in fact, is to join the slow drying solvent, so that the wet film surface solvent volatilization rate is reduced to prevent the formation of a “cold bed”. When adding white water, first add white water into tianna water and stir well, then add tianna water into paint normally, the general amount of adding is: tianna water: white water = 9:1 (weight ratio). The maximum adding amount can be increased to 20% of tianna water. If the paint film is still white, you should stop painting and wait for the temperature and humidity of the environment to decrease before construction. Because adding too much water will make the paint film dry too slowly, become soft and sticky, and affect the quality of the paint film.

5、Adopt the right method to keep the indoor painting environment in line with the requirements. It is wrong to open windows and doors wide for ventilation when it is rainy and cloudy outdoors. It is wrong to open the doors and windows and even force ventilation at this time.


15、What is called “wet touch wet” spraying, which processes in the spraying construction, which species can be “wet touch wet” spraying, how to operate?

A: “Wet touch wet” process from the industrial baking paint coating. From the original two spray a grinding two baking (spray – baking – grinding – spray – baking) to two spray a dry. When is the best time to “touch” it? The key is to let the solvent of the first wet film evaporate to the maximum extent in the appropriate interlayer interval time under the prevailing environmental conditions, so that there are no pinholes, bubbles and hangings in the curing process of the second paint film. The appropriate interlayer time varies depending on the weather, substrate, paint type and wet film thickness, usually within a suitable period of time after surface drying.


In order to “touch” well, the principle should be “under should be slightly thin, on can be thicker”. The most easy to “touch” bad operation is “the lower layer is too thick, the interval between layers is not enough time”. This is to emphasize, because “seeking change must have a section, the desire for speed is not achieved”. If it is “wet touch dry”, “dry” should generally be lightly ground to ensure adhesion, another should do the test, to prevent “wet” will be “dry ” bite up.


“Wet touch wet” process is usually applied to PU polyester primer, NC nitro primer spraying. PU, NC paint a thick spray is often easy to produce pinholes, bubbles, hanging and other phenomena. In order to avoid this phenomenon can be sprayed first (usually one refers to the spraying of two cross), when the first paint film to reach the surface dry, for cross-linking curing PU type primer has a preliminary cross-linking reaction. For volatile NC type primer, most of the solvent in the paint film has been evaporated when the first film is surface dried. The first paint film began to curing, then spray the second paint, because the first film is not completely cured. For PU type, the two paint films participate in the cross-linking reaction together, and for NC type, the two paint films penetrate each other. Whether it is PU class or NC class, the second paint film will be fused into one, without interlayer sanding, and the adhesion is also very good, as if it is a spraying of the paint film.


For PE paint, its own characteristics is a thick spray does not produce pinholes, bubbles, therefore, PE paint generally does not use “wet touch wet” spraying process, usually PE primer is a continuous spraying completed.


Through the above analysis, the “wet touch wet” spraying process, according to the actual situation, flexible control of the application, in order to obtain good results in quality and economy.


16, the same barrel of matte varnish, at the beginning of use, gloss brighter, and the more later, its gloss is getting lower and lower, until finally, into a full sub, what causes this?

A: To solve this problem, the first step is to clarify the characteristics of matte varnish composition, usually matte varnish composition in addition to resin, solvents, additives and other basic components, there is a matte varnish to determine the gloss of the matte powder. The matting powder is not dissolved in the paint. Instead, it is dispersed and suspended in the paint as a particle. The specific gravity of the matting powder is larger than the other components, therefore, after a period of storage, the matting powder will slowly settle and a large amount of matting powder will accumulate in the lower part of the barrel, and the closer to the bottom of the barrel, the more the amount of matting powder will accumulate. When using paint, if you do not stir the whole barrel of paint, or stir it, but not enough, it will cause a barrel of paint, different parts of the paint matting powder content, or different pouring times of the paint matting powder content is not the same. This will result in the whole barrel of paint in the beginning of the use, the luster brighter, and the more to the bottom of the paint, its gloss is getting lower and lower phenomenon. Therefore, before taking the paint from the barrel every time, make sure to stir the whole barrel of paint from the bottom to the surface with a stirring rod, not only in the stirring direction, but also in the surrounding direction, the stirring rod should be pumped up and down, and the stirring rod should be inserted to the bottom of the barrel before lifting up, so that the bottom part of the barrel sediment and the surface layer of paint are mixed evenly. At this time, then take out the paint and use it according to the required ratio. Only in this way can the paint performance (including gloss, hardness, fullness, covering power) be consistent every time you use it.


Emphasis here: matte paint precipitation is absolute, not sink is relative. A good matte paint is allowed to precipitate, but it is better to be able to use it after it has been fully stirred well. If it is not placed for a long time, the matting powder will be sunk in the bottom in a large number and become lumpy and seriously layered, and it is difficult to be even after stirring, and it is difficult to paint the qualified effect, it is not the best.


17、Why does the oil running phenomenon appear in the spraying construction?

A: The paint shrinks on the surface of the object to be coated, forming like beads, pinholes and other shapes of different sizes, such as water spilled on wax paper, spots to reveal the bottom layer, this phenomenon is called “oil running”. It is also called “laughing”, and PE paint has a higher chance of running oil. The cause of “oil running” is due to the poor wetting of the paint on the painted surface or the high surface tension.


The reasons for oil running are as follows.

1, the bottom layer or paint mixed with oil, wax, moisture, affecting the adhesion of the paint film, the surface tension of the paint film to shrink the film run oil.

2, there is a non-drying thinner in the bottom layer of paint, such as kerosene, diesel fuel, not evaporated in time after drying to apply top coat.

3, the bottom layer of paint is too smooth, and the adhesion of the surface layer is less than the surface tension of the surface layer of paint and produce oil running.

4, poor wettability of the paint or mixed with too much silicone oil, are not easy to form a uniform film layer, easy to run oil.

5, spray room air is polluted, such as spray room around the polishing, acid vapor volatilization and other processes of the factory (such as shoemaking, pickling, electroplating), with the change of wind direction will be oil, acid vapor blown into the spray room, so that the paint film oil run.


The method of dealing with oil running.

1, deal with the grass-roots level, the application of coating shall not have oil, wax, moisture, etc. To check the separation effect of oil and water separator, check whether there is oil and water vapor in the airway, if there should be treated clean before spraying construction.

2、The viscosity of the paint construction should be moderate, and choose the solvent with slow volatility, such as changing the winter thinner to summer thinner.

3, try to avoid construction in cold, humid, smoky environment, spray room should not be established in the vicinity of the factory with polishing, acid vapor volatilization.

4、The amount of silicone oil mixed in the paint should be appropriate, excessive mixing will produce oil running.

5、If oil running is found during the construction, the construction should be stopped immediately to check the cause of oil running, and then construction after elimination.

6、The workpiece that has run oil should be sanded smoothly after all of them are dry, and then reapplied.


18、What is the importance of sanding process in furniture painting? How to choose sandpaper in the process of sanding?

A: As the saying goes: “10 points of painters, three points in the sand”, which shows the importance of sanding in the painting operation.

Sanding process has three main roles: ① for the substrate is to remove the burr on the surface of the substrate, oil and dust, etc.; ② for scraping the surface of the putty, the surface is generally rougher, need to obtain a flatter surface through sanding, so sanding can reduce the roughness of the workpiece surface role; ③ enhance the adhesion of the coating. Before spraying new paint film generally need to dry the old paint film layer for sanding, because the coating in excessive smooth surface adhesion is poor, after sanding can enhance the mechanical adhesion of the coating.


The methods of sanding are dry sanding, wet sanding and mechanical sanding.

①Dry sanding: sandpaper is used for sanding. It is suitable for the sanding of hard and brittle paint, but the disadvantage is that the operation process will generate a lot of dust, which will affect the environmental hygiene.

②Wet sanding: use water sandpaper dipped in water or soapy water to sand. Water sanding can reduce the abrasion marks, improve the smoothness of the coating, and save sandpaper and effort. However, after the water grinding should be noted when spraying the next layer of paint, one is to wait until the water grinding layer is completely dry before applying the next layer of paint, otherwise the paint layer is easily whitened. Another very absorbent substrate is also not suitable for water grinding.

③ Mechanical sanding: When constructing a large area, in order to improve efficiency, mechanical sanding methods can be used, such as electric sanding machines (disc type, vibration type).

19、Why will bubbles and pinholes be produced when spraying construction?

A: Spraying construction bubbles, pinholes are analyzed as follows.

1, the phenomenon: in the coating surface first appear many large and small bubbles, followed by bubble rupture or grinding in the paint film that is formed when the dense such as pinhole-like holes.

2、Cause: Gas (solvent vapor, water vapor, expanding air or other gases that can be mixed into the paint, such as carbon dioxide, etc.) breaks through the coating to form bubbles, which then break or grind to form pinholes. When the surface layer of the coating dries at a slightly higher rate than the interior, when the surface layer has begun to condense and the interior solvent or air continues to evaporate, it will break through the surface layer of the coating to form bubbles. This is related to the following situations: the viscosity of the coating is too high, a thick coating, thick and deep wood conduit, filling holes containing air; spraying air pressure is too high, too much air mixed in the coating; the surface is coated with oil, dust, sweat, etc., these unclean things around the collection of water; coating and the coated surface temperature difference is too large; improper use of thinner, curing agent added too much or with the wrong curing agent; painting environment temperature is too high or The relative humidity is too high; the drying of the lower coating is not completely applied to the upper coating, and the upper coating is dried rapidly; when using heating to dry the coating, the temperature is too high, the resting time before heating the coating is not enough, the solvent is not fully evaporated, the paint itself brings in bubbles, and the bubbles generated when stirring are not eliminated, etc.

3、Exclusion method: Check the coating process conditions for the above reasons, adjust the suitable coating viscosity, use the appropriate amount of thinner and curing agent, control the thickness of the coating; do a good job of filling holes in the substrate, sanding, eliminate the pollution of the substrate; adjust the appropriate air pressure, reduce air mixing; improve the operating environment, control the appropriate temperature and humidity; appropriately lengthen the recoating time, so that the lower layer is fully dry; after the paint is deployed to After the paint is prepared, it should be left to stand for 20 minutes before spraying; when using heating to dry the coating, control the standing time to make the solvent evaporate fully before pre-heating the coating.


20、What are the requirements and environmental conditions for the components suitable for cracking paint?

A: 1, flat, curved and other complex shaped shaped parts can be sprayed with cracking paint.

2、The moisture content of the blank must be in line with the local equilibrium moisture content.

3、The one-time continuous spraying area of flat or curved surface cannot exceed 2 square meters, otherwise it should be constructed in pieces.

4、The construction site should be well ventilated and well lit to facilitate observation of the effect.

5、The construction site should be convenient for the construction personnel to walk freely, there should not be too many obstacles, and scaffolding should be set up for construction at height to facilitate the construction personnel to walk freely


21、What is the cause of cracking paint not cracking?

A: 1、Crackle paint or nitrocellulose varnish is not smooth and full enough after painting;

2、Crackle paint or nitrocellulose varnish drying time is too long;

3、The air pressure when spraying cracked paint is too large, the oil volume is too small or the distance between the spray gun and the surface is too far;

4、Negligence during construction, not fully stirred after the paint is opened


22、What are the precautions of cracking paint construction?

A: 1、Before cracking primer, try to make the bottom with two-component paint.

2、Cracking bottom should be selected with one-component paint. (mainly with NC type or special cracking bottom)



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Sinocure® 1206 Photoinitiator APi-1206

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