Color mixing is a very important basic skill in the printing and dyeing industry. Scientific color mixing methods can greatly improve production efficiency and reduce resource waste.
Preparation before color mixing.
1.Physiological preparation
The accuracy of color adjustment is much higher when people are well rested and energetic than when they are tired; when visually inspecting a color, the accuracy of the first visual inspection is higher than the accuracy of repeated visual inspection for a long time. Therefore, in a good mental state, concentrating on visual inspection results in a short period of time is the physiological prerequisite for efficient color grading.
- Dye selection
According to the customer’s sample, we must first understand the customer’s color requirements. If the customer requires multiple light sources for color matching, computer color measurement is required to select the dye to avoid or reduce metamerism between the printed sample and the customer sample. It is necessary to understand the various fastness properties of the selected dyes and the various fastness requirements of the customers; it is also necessary to understand the ease of operation, stability and safety of the selected dyes. Finally, we need to consider minimizing costs and reducing emissions.
Color mixing of three primary colors
Three primary color dyeing is a common method, and many customer samples can also be dyed with three primary colors. If the properties of the three primary color dyes used in the customer sample are similar or consistent with the dyes used for proofing, there will be little or no metamerism. . General dye manufacturers will recommend three primary color combinations with different dyeing depths based on the directness, migration, diffusion, lifting, reactivity and other indicators of each dye. For example, Clariant acid dyes include three light primary colors: Yellow E2RL or E4RL, Red EBNL, and Blue EBGL; three medium primary colors: YellowN3Rl, Red N2RBL, and Blue NBLN; medium and dark economical three primary colors: Yellow N3RL, Rubine N5BL, Blue NRL or NRBL. After choosing a dye, you need to get the first prescription. There are generally two ways:
One is to use computers and software to automatically search for the first close prescription from the database previously entered into the computer; or based on the color data of different concentrations of each single dye (also called monochrome data) entered into the computer, the computer calculates Get your first prescription.
Second, it is obtained based on the retained historical sample cards. Many experienced colorists usually accumulate a lot of historical sample cards. After customers come in for samples, they can look through them to find close historical sample cards, and then get the first prescription after correction. The following explains the three primary color coloring methods based on the continuous pad dyeing processing method.
- Depth first, hue second
Human eyes are very sensitive to hue among the three elements of color, followed by purity and slower to brightness. The color of the same dye will change at different concentrations, especially darker colors, such as Clariant Navy
NRBL, the darker the blue, the redder the light. Moreover, the dye reaches saturation after dyeing to a certain depth. Even if the amount of dye is increased, the amount of color obtained will not increase. In this way, if the hue is the same but the depth is different during color matching, increasing or decreasing the dyes in the color matching in the same proportion will often lead to changes in hue and light. Therefore, if you first adjust the depth while ensuring that the hue is close, and then adjust the hue, so that the dye used for subsequent adjustments increases or decreases very little, the human eye will not feel the change in depth, but the change in hue will be clearly reflected. Generally speaking, as the depth of bright red increases, its color becomes more yellow; as the depth of maroon increases, its color becomes bluer and black; as the depth of sapphire blue increases, its color becomes redder; as the depth of black increases, its color becomes redder and yellower; The darker the brown color, the bluer its color. Once you have mastered the law of color changes with depth, you can also adjust the depth and hue at the same time, and the color adjustment efficiency will be higher.
- Percent addition and subtraction algorithm
Percent addition and subtraction is a basic algorithm in color grading. For example, if the mass concentration of a certain dye used for proofing is 1 g/L, then visual inspection or computer color measurement believes that it should be increased to 1.1 g/L. According to the algorithm, 10% should be added. - Swap method
The swap method is mostly used when the color adjustment movement is large. For example, if you use 0.5 g/L of a certain dye for proofing, and after checking the customer sample, you think it should be increased to 1 g/L, that is, an increase of 100%, then you can use the customer sample to check the sample to see if you want to use the customer sample as the dye. Subtract 50% of 1 g/L to the color of the sample. This allows the accuracy of the color correction to be verified and corrected. - Pincer attack method
The pincer attack method is to find the location of the customer sample from multiple samples that have been printed. For example, the dye dosage for printed sample A is 0.8 g/L, and the dye dosage for sample B is 1.1 g/L. After checking the customer samples, it is found that sample A is lighter and sample B is darker. At this time, the customer sample is placed between A and B. Visually, the distance difference between the color depth of the customer sample and sample A is twice that of sample B. In this way, the amount of dye used is about is 1 g/L. - Stepping method
The step method is to deduce the location of the customer sample from multiple samples that have been played. For example, the dye dosage of sample A is 0.7 g/L, and the dye dosage of sample B is 0.9 g/L. For the customer sample, the dosage of A and B is not enough. Visual inspection should increase the dosage from sample B to customer sample. The amount should be increased from sample A to sample B. Half, the dye dosage at this time is: 0.9 g/L+(0.9-0.7)/2 g/L=1 g/L.
- Law absolute
The absolute method is based on a full understanding and clear memory of monochromatic data, and is mostly used when a new dye needs to be added to the color mix. This dye has not been used in previous color mixing, so of course percentage addition and subtraction cannot be used. If the amount of newly added dye is relatively large compared to the main dye, a computer color measurement should be used to select the dye first to prevent metamerism. For example, if the red light of the small sample is different from that of the customer sample, visual inspection of the color depth of 0.1 g/L of a certain red dye can fill the gap between the small sample and the customer sample, that is, adding 0.1 g/L of this red dye to the color mixing prescription.
- Relative method
The relative method is often used when a new dye needs to be added to the color mix. The premise is that the shade, strength, and lifting power of each dye are fully memorized and understood. For example, in the sample formula, the dosage of dye A (strength 200%) is 10 g/L, and the dosage of dye B is 1 g/L (strength 100%). The main dye is dye A. Visual inspection requires adding dye C between the sample and the customer sample ( The dosage of dye C is 2% of the main dye A in the standard dosage. At this time, the dosage of dye C in the prescription is: 10 g/L × 2 % × (100 %/200 %) = 0.1 g/L. This method is generally used in conjunction with the absolute method to improve the accuracy of the color prescription. - Computer color grading
When the dyeing process conditions are fixed and controllable, and the input data system is correct, computer color matching has higher accuracy and stability. However, in practice, especially in workshop production, the effectiveness of computers will be greatly affected by various uncontrollable factors. Therefore, on the one hand, we must continuously strengthen and improve the controllability of production conditions, and on the other hand, we must strive to reduce the randomness of human operations, so that the role of computer color grading can truly be brought into play.
Non-primary colors
Restricted by certain dye selection conditions, such as to improve the stability of mass production; or the color light of a certain dye is close to the customer sample, and only a small amount of other dyes need to be added to adjust to achieve the customer sample color; or the customer has different preferences for the same color. The spectrum requirements are high and cannot be achieved with the three primary colors. In this case, non-three primary colors will be used for color matching or some non-three primary colors will be used for color matching. Such as bright red + orange + green, yellow + green + gray, dark brown + yellow brown + black, etc. According to the subtraction principle of color matching, the color light of non-primary color dyes can be understood as being made up of multiple three primary color dyes. In practice, the color light of non-three primary color dyes can generally be made up of multiple three primary color dyes. For example, bright red can be made up of about 20 of the three primary color yellows. % plus about 80% of the three primary colors of red. Because the dyes produced by various dye manufacturers have different shades, strengths, and lifting powers, in practice, you can use three primary color dyes to proof and color to a certain non-primary color dye shade to grasp the proportion of each three primary color shades contained in the non-primary color dye shade. content, laying the foundation for efficient color mixing of non-primary colors. After the chromatic light components of non-primary color dyes are clearly analyzed, the color can be mixed according to the color mixing method of the three primary colors.
