Three primary color inks (yellow, magenta, cyan) and black ink can be used to produce richly colored prints. However, for some product colors, it is difficult to achieve the effect of thick and bright colors through the superposition of ordinary dots, or From the perspective of process and cost, there is no need to perform color separation or multi-color printing. However, single color can print the special color effects required by the original color sample. This requires the printing of spot color inks, such as express mail envelopes on a large area. Because blue printing requires bright and thick colors, it is difficult to achieve the color effect of the original with four-color printing, so spot-color blue printing is required. In addition, some book covers, envelopes, letterheads, micro-marks, etc., because of high quality requirements ( Thick solid surface), small production quantity, short time limit, and low cost. Only by printing with spot color ink without color separation can the user's requirements be met.

It is impossible and unnecessary for ink manufacturers to produce inks of various hues. They only produce a few commonly used inks (such as four-color ink, gold red, bright red, medium blue, etc.), so for For printing plants, sometimes it is necessary to mix two or more original inks based on the original color samples provided by the user to obtain ink of a new hue. This process is the mixing of spot color inks.

In production, there is currently no simple and easy-to-operate color analysis and testing equipment, which basically relies on the experience of the ink adjusters, because the ink adjusters have no knowledge of spot color ink blending technology. Proper control often results in the brightness of the adjusted ink being incorrect, or the ink being printed on the machine only to find that the hue is incorrect and then adjust it again, resulting in quality accidents, ink waste, duplication of workers' labor, time delays and other unnecessary troubles. This requires us to adjust the spot color Ink blending technology must be fully understood and mastered.

The mixing principle of spot color ink and the color rendering principle of spot color ink

The mixing of spot color ink is based on the original color sample and the principle of subtractive color method of the three primary colors of ink. The physical effect presented by the pigment of the ink is called subtractive color method, that is, when the pigment displays a certain color, it means that the pigment achieves selective absorption (subtracting colored light) of various colors in the white light spectrum.

The color change rules of the three primary colors of ink subtractive color method are as follows:

Magenta + yellow = red

Magenta + cyan = purple

Cyan + Yellow = Green

Magenta + Cyan + Yellow = Black

Therefore, the mixing of ink pigments weakens the light green and is a color subtractive phenomenon. The more pigments are mixed, the final The color becomes darker and closer to black.

The color rendering principle of spot color ink is that the ink pigment presents effects through the subtractive color principle. For example, when yellow and blue inks are mixed in equal amounts, because the pigment in the printing ink is the main color of the ink, the particles are very small and are insoluble suspensions with a diameter of 0.01-0.5um. We print the mixed ink on paper and For partial amplification, when white light is irradiated, three situations may occur. I: When the white light is irradiated on the yellow ink particles, it absorbs the blue light and reflects the red and green light; II: When the white light is irradiated on the blue ink particles, it Absorbs red light and reflects green and blue light; III: When illuminated on yellow and blue mixed ink particles, it absorbs red and blue light and reflects green light.

Since equal amounts of yellow and blue ink are mixed, then II and III have equal chances, and the reflected light is as follows:

I: W-B-R=G

III: W－R＝B+G

The reflected light combination effect is:

3W－(2B＋2R)＝3G＋R＋S =W+2G

So the color after blending these two inks is green. If the yellow ink and blue ink are not blended in equal amounts, then the conditions of II and III cannot be equal. If more yellow ink is used, the ink will be more yellowish, otherwise the color will be more bluish. After mastering the color change rules of the three primary colors, you can draw inferences from one example to create the colors of various originals.

How to mix spot color ink

To mix spot color ink, the ink mixer must make three preparations: 1. The hue is accurately blended and meets the original color sample standard; 2. The ink is formulated for accurate printing suitability; 3. The exact quantity of spot color ink is dispensed.

Accurate color matching

1. Ink adjusters should have a deep impression and keen sense of the colors of various inks produced by ink manufacturers.

Ink adjusters must have a full understanding of the three attributes of various inks (hue, lightness, and saturation) so that the color matching can be adjusted to a spot color ink that matches the original color sample in the fastest time and with the least number of original ink types. Because the properties of color can be studied through the three parameters of hue, lightness, and saturation and used as a basis to measure the difference between two colors, using it to express and describe colors can obtain a unified color language, which is suitable for the needs of standardization and dataization.

2. Analyze the original color sample

a. Determine the main and auxiliary color ink. For the blending of spot color inks, after we have mastered the color change rules and characteristics of several commonly used inks, the analysis of the color sample of the original is the most critical, which is related to the accuracy of the hue of the entire ink. When analyzing the hue of the original, we can use the subtractive color method To consider the principle, it is to use the three primary color theory to analyze the content of the original color sample in the three primary colors to determine the ratio of the main color and the auxiliary color. Generally speaking, one primary color is the main color, and the other colors are the auxiliary colors.

When preparing Telecom Blue, the standard color of China Telecom Company, we observed that it gave us the impression that the main color is blue with a hint of red. The color of the entire ink is bright, thick and pure, that is, the brightness and saturation of the ink. Large, pure hue, so we mainly use sky blue, supplemented by brightly colored, purple-tinged peach ink. Although there is a color separation ratio on the sample, it is a comparison between the color separation on the electronic color separation or the desktop system and the actual color ratio. Printing inks are not compatible.

We cannot prepare China Mobile’s Mobile Blue because after its standard color is printed by a printing machine, there is an obvious color shift and the gray scale increases, giving people an old and dark feeling. Sticking to its color separation ratio, which is almost the same as Telecom Blue, the main color is medium blue with impure hue and darker brightness, as well as bright red, and a little black ink is added to increase the grayscale of the entire ink.

b. Obtain the ratio of the main and auxiliary color inks

After we determine the main and auxiliary colors, we mainly obtain the proportion of the main and auxiliary colors through the following ways: obtain the appropriate ratio based on past experience According to the ratio of similar color samples in the ink adjustment manual, use a small amount of original ink to adjust the sample to get the correct ratio.

c. Compare the color of the spot color ink with the original color sample

Use a piece of paper (usually coated paper, offset paper) to dip a small amount of spot color ink into it. Use the "scraping method" or "blowing method" to obtain an ink sample, and compare it with the color sample of the original so that you can adjust the ratio if there are differences.

Things to note when matching colors:

The ideal light source for one-tone ink color discrimination is uniform white light, natural light from a north-facing window, and artificial light sources similar to natural light, such as fluorescent lamps and Incandescent lamps are mixed with light sources;

- The prepared ink color sample is darker than the original color sample, because the hue of the offset ink will become lighter accordingly after the fountain solution is mixed and the ink dries. In addition, correct hue and deep ink (high saturation) can reduce the amount of ink, which is beneficial to the ink balance control of offset printing;

- Consider the properties of the substrate paper, such as whiteness, absorption properties, smoothness, etc. If the properties of the paper are far different from those of the original paper, it must be analyzed according to the specific situation. For example, it is also Telecom blue, but a user once requested to use pink fragrant cardboard to print the Telecom logo. If Telecom is used With the original blue ink mixing method, the printed color effect will be dark and gray, and the overall hue is far different from the original. We can directly use sky blue ink printing and match the paper to produce a color effect similar to Telecom Blue.

- It is necessary to consider the influence of the surrounding environment of the color sample to avoid color illusions. When identifying colors, the surrounding colors should be covered up and observed alone to avoid color deviation.

- When using rubbing and scraping methods to obtain the ink layer, the thickness of the ink layer of the spot color ink must be basically similar to the thickness of the ink layer of the original color sample.

The printability of spot color inks requires appropriateness and accuracy

Generally, when blending printing properties of spot color inks, the viscosity, fluidity and drying properties of the blended ink are mainly considered, but now with the With the development of the ink industry, various inks have better adaptability and compatibility. Generally, we do not need or only need to add an appropriate amount of ink additives, such as special effect ink additives or ink-adjusting oil, etc., to change the suitability of the blended ink. You can achieve better printing results.

Notes: The ink must be mixed evenly; if the paper is coated paper or coated paper, quick-drying ink should generally be used, while resin ink can be used for offset paper.

Preparing the correct amount of spot color ink

Preparing the correct amount of ink mainly considers the following factors: the number of prints; the emphasis on the ink absorbency of the paper; the area of ??printed graphics and text; spot colors The coloring power of the ink; the thickness (density) of the spot color ink, etc.

If too much ink is blended, the remaining ink will be wasted. If too little is not enough, it will need to be blended again. If complex colors are encountered, the ink blended the second time will be difficult to be exactly the same as the first. , which has an impact on product quality. Therefore, the actual printing amount should be slightly exceeded when blending. This is also to avoid changes in the imprint ink color caused by the inventory in the ink fountain falling below a certain value.

The preparation of dark ink and light ink

The preparation of ink can generally be divided into the preparation of dark ink and the preparation of light ink.

The preparation of dark ink

Only the original color ink is used without adding any diluent. It is collectively called the preparation of dark ink. During the preparation, the main and auxiliary colors are based on the aforementioned color sample analysis results. After determining the color, according to the designed ratio, use the auxiliary color ink to add the main color ink one by one and mix thoroughly. According to the theory of subtractive color method, when blending inks, the types of primary color inks should be used as little as possible, otherwise the brightness of the ink will be reduced and the vividness of the color will be affected.

Preparation of light-colored ink

Any ink prepared by adding diluent is collectively called the preparation of light-colored ink. Because light-colored ink has less irritation to the human eye, it generally needs to be Use a magnifying glass to analyze the color sample of the original, remove the diluent, and determine the main color. Then pay attention to the color cast of the ink. Generally, you can gradually add primary color ink to the diluent in small amounts to prepare it.

Light-colored ink is generally made by adding diluent or original ink to white ink. Pay attention to the light-colored ink that is mainly composed of white ink. Its tone is powdery, the ink color is brighter, and it has strong coverage. ability. Because white ink pigments are easy to pile up on plates and blankets, and have poor light resistance, they are suitable for single-color printing on solid surfaces. They are generally pink, blue, and pink spot color inks. Light-colored inks based on diluents have a certain degree of transparency, no covering power, and bright colors. They are suitable for multi-color overlapping printing. They are generally light red, light yellow, light gray and other series of spot color inks.

To sum up, the blending of spot color inks is more complicated and difficult because it involves light and color theory, ink, paper, technology, etc., and it is basically based on experience at present. , so the requirements for ink adjusters are relatively high. First of all, they must master the theory of light and color, and secondly, they must master the properties of commonly used inks. They must have a keen and accurate ability to identify colors, and they must constantly and consciously practice their applications through practice. Ability, that is, when seeing a certain hue, you can quickly and roughly report the ratio of ink. Only in this way can we quickly and accurately prepare spot color inks, better provide quality services for production, and improve product quality.

Elements of formula design of water-based flexographic ink

1. Concept of water-based flexographic ink

Water-based ink is composed of water-based polymer resin, emulsion, and organic pigments , solvent (mainly water) and related additives are mixed through physical and chemical processes. Water-based ink does not contain volatile organic solvents, is non-flammable, does not harm the health of ink manufacturers and printing operators, and does not pollute the atmospheric environment. As a new type of printing ink, water-based ink does not have some toxic and harmful substances in solvent-based ink remaining in printed matter and contaminating packaged goods, which improves the overall environmental quality.

Water-based flexographic ink is named according to the classification method of ink according to printing plate type and combined with the drying mechanism of ink.

2. Technical basis for water-based flexographic ink formula

1. Neutralization and salt-forming mechanism of water-based binder

Water-based ink uses water-based binder. Water-based binders are basically divided into three categories: colloidal dispersions, emulsion polymers, and water-diluted polymers. At present, the ink industry mainly uses dilute connecting materials. Many polymers (water-soluble) are not originally soluble in water or are only partially soluble in water. Only by adding an acid or alkali can they become soluble in water due to ionization. Typical examples are polyacrylic acid and polyamide, which are anionic and cationic electrolytes respectively. The pH value of the aqueous solution of these substances is closely related to its viscosity, flocculation effect, stability, dispersion, etc. Therefore, the molecular chain of water-soluble polymers contains a certain number of strongly hydrophilic groups, such as carboxyl groups, hydroxyl groups, amine groups, etc. However, most of these polar groups can only form emulsions when mixed with water.

Carboxylates are soluble in water, so the manufacture of water-soluble binders often uses highly acidic synthetic resins, which are then neutralized with amines to form salts.

2. Drying film-forming mechanism of volatilization, penetration, curing reaction or a combination of the three

Generally speaking, the printing process and the corresponding drying method determine the ink formula system used. In order to meet the process requirements of flexographic printing and the characteristics of water-based ink itself, according to different printing substrates, the drying methods of water-based flexographic ink include volatilization, penetration, curing reaction or a combination of the three.

(1) Volatile drying mechanism

For flexographic printing where the substrate is a non-absorbent substrate, the drying method is mainly volatile drying, that is, using resin/solvent Ink system. Because:

① The speed of flexo printing machines is very fast, ranging from 80m/min to more than 200m/min. Generally speaking, the interval from the first color printing to the second color printing is only a few seconds to a few tenths. Second. For non-absorbent substrates, of all drying types, only volatile drying meets this requirement.

② Only when the liquid in the ink film comes out of the ink film as soon as possible, for example, by using a solvent with a low boiling point that evaporates instantly, can the ink dry quickly. Quick drying also requires the ink to be a low viscosity and thin liquid.

③For offset printing ink and lead printing ink, the ink can be evenly coated on the printing plate through coordination between the ink rollers, while flexo printing ink only relies on its own fluidity and adhesion. It can fill the mesh of the anilox roller and transfer the ink to the printing plate. Only a liquid with a lower viscosity, that is, a thinner liquid can give such properties. Moreover, the ink must fill the concave holes in a short period of time. If the viscosity is too high, it will be difficult to fill the concave holes. At the same time, it will be difficult for the scraper to smoothly scrape off the ink on the screen wall. Therefore, flexographic ink is generally in the form of a fluid with a low viscosity, and a large amount of solvent or water can only be evaporated or penetrated. Of course, it is not good if the viscosity is too low, otherwise the ink in the dots will be easily deformed during imprinting, which will worsen the reproducibility of graphics and text.

The drying speed of ink first depends on the evaporation speed of the solvent in the ink. The volatilization of solvents in inks mainly has the following influencing factors:

① Different resins slow down the evaporation rate of solvents to different degrees. The higher the solubility of the resin, the harder it is for the solvent to escape and the lower the volatilization rate.

②The greater the proportion of pigment in the ink, the lower the evaporation rate of the solvent; the smaller the radius of the pigment particles, the larger the specific surface area, the lower the evaporation rate of the solvent; different types of pigments have different effects on Solvent releasability is not the same.

(2) Penetration absorption drying

For flexo printing on absorbent substrates, the drying method is mainly penetration absorption drying. Absorbent substrates such as paper absorb ink. The binder in the ink is a liquid film-forming substance that can bind the pigment particles and make them stick to the paper surface. After the binder is transferred to the paper, it penetrates into the paper until the pigment particles in the ink become closely enough, and the gap between the particles continues to shrink. The capillary tension between the pigment particles generated by the capillary pulling force is equal to the absorption bonding force in the paper. Absorption and penetration process. The degree of penetration of the connecting material into the paper is directly proportional to the capillary tension in the paper, that is, the ink absorbency of the paper depends on the degree of looseness inside it, that is, the tightness and tissue evenness of the paper. During actual printing, the effects of printing pressure, imprinting time, and ink viscosity should also be considered. Olsson's formula basically summarizes the relationship between the above factors on the depth of ink being pressed into the paper: d = (p×r2×t/2η)1/2

d: the depth of ink being pressed into the paper

p: printing pressure

r: paper capillary radius

eta: ink viscosity

Since the printing pressure is much greater than the capillary attraction, the following are ignored.

Penetration and absorption of ink onto absorbent substrates is important to the ink curing and drying process. If the amount of penetration is too small or too shallow, the ink will not adhere firmly and will not dry easily. However, if the amount of penetration is too large or too deep, it will cause print-through problems and reduce the gloss of the ink. In addition, for absorbent substrates, there is also a volatilization and drying mechanism at the same time. Therefore, for flexo printing on absorbent substrates, the drying method is a dual film-forming mechanism of volatilization and penetration. In the preparation of inks with certain special requirements, some reactive groups are also introduced to further improve its film-forming properties.

3. Many factors affecting the formula design of water-based flexographic ink

1. Requirements for printability

The ink moves from the ink tank to the printing plate The process of printing substrate is the transmission and transfer separation process of ink. Firstly, it is required that ink can always be stably transferred to the printing plate during the printing process. Secondly, it is expected that the ink on the plate can always be effectively transferred to the substrate in a certain state. The quality of transmission and transfer is related to the performance and accuracy of the printing machine, and at the same time requires the ink to have corresponding printability. The rheology of the ink itself becomes an important factor governing the suitability of the ink. Rheology includes viscosity, yield value, thixotropy, fluidity, adhesion, ink length, etc.

Viscosity The size of the cohesion of the ink must meet the requirements of the entire printing process.

(1) The higher the printing speed, the smaller the viscosity of the ink required. Fast printing requires fast transfer and fast drying, that is, the ink has low viscosity and is easy to separate, and the solvent can easily escape from the surface of the ink film. Practice has proven that the plastic viscosity of the ink has a significant impact on the transfer rate of the ink. Under the conditions of the same printing machine speed and the same speed, the split state of the ink layer with a small viscosity is more beneficial to the transfer of the ink than the one with a large viscosity. As shown in Figure 1.

(2) Substrate requirements: For relatively smooth coated paper, when the ink supply is sufficient, the transfer rate is high, so the viscosity of the ink is required to be slightly higher; for paper with a soft structure such as offset paper, The ink viscosity should be slightly lower.

Thixotropy Thixotropy is "shear thinning". The ink should have a certain degree of thixotropy. After the ink is mechanically rotated on the ink roller during the printing process, the fluidity of the ink will change. The viscosity will decrease, the fluidity will increase, and its ductility will also increase. Conducive to smooth and even transfer of ink. After the ink is transferred to the substrate, it loses the effect of external force. Because of its thixotropy, it quickly changes from thin to thick without flowing around, ensuring the accuracy of the imprint. Especially for dot and text line printing, it can avoid the expansion of dots and thickening of lines caused by the infiltration and spreading of ink on the paper. The thixotropy of ink is related to the following factors:

(1) Properties of pigments Inks made of pigments with strong surface adsorption have large thixotropy.

(2) Shape of pigment particles When the pigment particles are needle-shaped, the ink is more thixotropic than the ink made of spherical particles.

(3) Pigment dosage Generally, the greater the proportion of pigment in the ink, the stronger the particle interaction, and the greater the thixotropy of the ink.

(4) The wetting ability of pigment particles and connecting materials is low and the ink has high thixotropy.

(5) Molecular weight of the resin The greater the molecular weight of the resin in the connecting material, the greater the thixotropy.

Printing suitability requirements for thixotropy: Printing operations require that the ink has appropriate thixotropy. However, if the thixotropy of the ink is too large, the ink supply in the ink fountain will not be smooth, and even supply problems may occur. The phenomenon of ink interruption affects the uniformity and accuracy of ink supply during continuous printing. Different types of printing have different effects on the thixotropy of inks. Generally, the printing of screen printing plates, text printing plates and line printing plates requires slightly larger thixotropy of ink; for large-area solid printing plates, slightly smaller inks are suitable.

Adhesion During the printing process, the force that causes the ink film to split and transfer to the corresponding surface (ink roller surface, printing plate surface or substrate surface) is adhesion, that is, the ink and ink The connection force between the roller, printing plate and substrate surface. Under the action of adhesion, the ink first splits and then transfers. This is the dynamic response of the ink to the adhesion force. The ability of the ink itself to prevent the separation of the ink film during this dynamic process is called the adhesion of the ink. It is essentially a manifestation of the cohesion of the ink (the connection force between the ink molecules) under the action of adhesion. The impact of the adhesion of the ink on the printability is as follows:

(1) When the adhesion of the ink is large, the separation of the ink is difficult, resulting in uneven ink extension on the printing machine. When the ink layer separates between paper or blanket, if the resistance greatly exceeds the binding force of the paper, fuzzing or even peeling will occur.

(2) When printing with multiple colors, quickly print the next color while the ink of the first color is still wet. Generally, the stickiness of the first color ink is required to be greater, and the adhesiveness of the subsequent inks must be gradually reduced. Adhesion, otherwise, the subsequent printing may not be able to go on, and the previous ink layer will stick away.

Ink adhesion and drying After the ink adheres to the substrate, it changes from a liquid gel to a solid film and adheres to the substrate. This process of change is called the drying of the ink. .

This process is completed in two stages: the ink changes from liquid to semi-solid and can no longer flow and transfer. This is the initial drying stage of the ink, which is expressed by initial dryness. The main part of the binder in the semi-solid ink undergoes a physical or chemical reaction and completely dries to form a film. This is the complete drying stage of the ink, which is expressed by thorough dryness. The initial drying stage and complete drying stage of ink are collectively called the fixation and drying of ink. The drying speed of ink is related to the drying method of ink. The drying method of the ink depends on the components of the ink binder. Different printing methods, substrates and printing machinery have different requirements for ink drying. The fixing and drying performance of ink affects the printability in the following two points:

(1) For paper substrates, the ink can flow into its depressions and gaps and be fixed. This is done mechanically. "anchoring effect" and adhesion; for substrates with smooth and non-absorbent surfaces, the adhesion of the ink depends on the wetting effect of the ink on the substrate, that is, the affinity of the liquid to the solid surface, and also depends on the interaction between the molecules of the ink and the substrate. force. However, during high-speed printing, the distance between molecules will be drastically reduced due to the accumulation and adhesion of paper, resulting in a significant increase in the binding force between the molecules of the ink and the substrate, and the wet ink will be reflected on the back of the next printed sheet. Therefore, generally speaking, without affecting the adhesion between the ink and the substrate, the adhesion ability of the ink should be appropriately reduced, or the fixation and drying of the ink should be accelerated to avoid "back smearing" of the printed matter.

(2) The drying speed of the ink affects the adhesion of the ink. As shown in Figure 2, as the drying time increases, the viscosity of the ink gradually increases to the maximum value and then drops to zero. If the ink dries quickly and the surface of the ink film becomes smooth and smooth quickly and loses its adhesion, it will be difficult for the second color ink to adhere, and the ink will "crystallize". Ideal overprinting should be done from the time when the ink is first dry to completely dry.

If the drying is too fast, the ink will crust and paste on the surface of the printing plate, causing the ink to accumulate on the printed product, resulting in poor gloss and "ink spots"; if the drying is too slow, "smearing" may occur on the back of the printed product. "Phenomenon.

2. Requirements for packaging performance

Hiding power The area that can be printed by the unit weight of the original ink is usually called the hiding power of the ink, and the unit is m2/g. The hiding power depends on the following factors:

(1) The specific gravity of the ink. The printing area of ??an ink with a large specific gravity is smaller than that of an ink with a small specific gravity of the same weight.

(2) The amount of ink transfer The amount of ink transfer is affected by the hardness of the ink fountain roller and printing plate material, the ink-carrying capacity and wear of the ink holes of the anilox ink transfer roller, and the installation position of the doctor blade.

(3) The content of the colorant in the ink determines the hiding power of the ink.

(4) The hiding power of ink on uncoated paper or other absorbent printing materials is worse than that on non-absorbent printing materials, because the ink can penetrate into the absorbing material to make the color brighter. reduce. When printing paper, water-based ink penetrates into the paper slower than solvent ink, and its hiding power is higher than solvent ink with the same color intensity.

Resistance, chemical resistance, scratch resistance, heat seal resistance, grease resistance, freezing resistance, durability, etc.

The above discusses many factors that affect the performance of water-based flexographic inks. On this basis, the selection and preparation of the basic formula, binder system and raw materials can be further determined, and the general performance requirements and technical indicators of the developed varieties can be predetermined.

Problems and solutions to screen printing UV ink

Introduction

1. There are bubbles in the printed product after printing

UV ink Do not add additives and mismatched diluents casually. If this phenomenon occurs during normal use, please contact the manufacturer for assistance.

2. The screen sticks to the substrate during printing

The viscosity is too high, please add appropriate diluent.

Increase the distance between printed matter and screen.

3. The printed matter becomes sticky or does not solidify after curing.

Check whether there is a circuit problem.

Prolong curing time.

Increase the power of the lamp

4. Insufficient adhesion of the ink film after curing

Choose ink suitable for printed matter.

Whether the surface of the substrate needs to be treated.

5. The ink film becomes brittle after curing.

Is the ink film too thick?

Choose an ink suitable for the print.

6. The printed product has pattern defects

The screen must be cleaned thoroughly to prevent light curing due to long downtime.

Check whether the production of the screen version is defective.

7. The ink film has insufficient or excessive covering power

Adjust the angle of the scraper and the pressure on the screen.

Replace the scraper with a suitable hardness.

8. The lines are blurred when printing small text or fine patterns.

Replace the scraper with a suitable hardness.

9. Reticulation appears.

Appropriately add matching diluent to reduce viscosity.

10. Smell version

Too much diluent is added and the viscosity is too small.

The mesh is inappropriate.

Note: In addition to the above problems, there are also some problems similar to those of coatings, such as curing problems, adhesion problems, bubble problems, etc. For solutions, refer to the coating product solutions.