Preface
Dyes are generally organic compounds, and most organic compounds are colorless. The color of dyes is the result of their different absorption properties of light waves of various wavelengths. The color they represent is the complementary color of the absorbed light.
Dye color matching three primary colors: red, yellow, and blue. (The red, yellow, and blue here refer to the primary colors magenta, yellow, and cyan respectively for subtractive color mixing). Orange, green, and purple can be obtained by combining two different primary colors, which are called secondary colors. Use two different secondary colors to combine, or combine any primary color with black or gray to get tertiary colors.
Preparation before color mixing
1. Physiological preparation
People are well rested and energetic The accuracy of color adjustment is much higher under normal conditions than under fatigue; the accuracy of the first visual inspection when visually inspecting a color 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.
2. Selection of dyes
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 (hereinafter referred to as the customer sample).
It is necessary to understand the various fastness properties of the selected dyes and the customer’s various fastness requirements; 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.
Coloring of the three primary colors
The coloring of the three primary colors is The most common method. Moreover, many customer samples are commonly dyed with the 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 obtain the first prescription. There are generally two ways:
One is to use computers and software to The computer automatically searches for the closest first prescription in the database previously entered into the computer; or based on the color data (also called monochrome data) of different concentrations of each single dye entered into the computer, the computer calculates the 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 the customer’s sample comes, they can look through it to find the closest historical sample card, and get the first prescription after correction. The following explains the three primary color coloring methods based on the continuous pad dyeing processing method.
1. Depth first, then hue
Human eyes compare colors Among the three elements, hue is the most sensitive, followed by purity, and lightness is slower. The color of the same dye will change at different concentrations, especially for darker colors, such as ClariantNavyNRBL. The darker the blue, the redder the color. 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 consistent 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, the color becomes yellower; as the depth of maroon increases, the color becomes bluer and black; as the depth of sapphire blue increases, the color becomes darker. Red; as the depth of black increases, its color becomes more reddish and yellow; as the depth of brown increases, its color becomes bluer. 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.
2. Percent addition and subtraction algorithm
Percent addition and subtraction algorithm is Basic algorithms 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.
3. Transposition method
The transposition method is mostly used for color adjustment. When larger. 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 a 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.
4. Pincer attack method
The pincer attack method starts from the Find the location of the customer sample among multiple samples. 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.
5. Stepping method
The stepping method has been The location of the customer sample can be deduced from the multiple samples produced. For example, the dye dosage for sample A is 0.7 g/L, and the dye dosage for sample B is 0.9 g/L. For customer samples, the dosage of A and B is�5 points, yellow 6 points, blue 8 points → yellow, gray and red 5 points, yellow 8 points, blue 16 points → blue, gray and red 10 points, yellow 3 points, blue 8 points → red gray
Color matching is a complex and meticulous work. In order to prevent obvious color differences, the following principles should be mastered when color matching:
Color matching The dyes should be of the same type. The fewer the types of dyes, the better. This will facilitate dyeing with the same method, otherwise it will be easy to dye flowers.
The dyeing properties of the dyes used for color matching should be similar, such as dyeing temperature, affinity, diffusion performance, fastness, etc., otherwise there will be defects of different colors and lights
The concentration of each dye used in color matching must be consistent, otherwise the original color cannot be spelled out.
When using color matching, the types of dyes should be as few as possible. If you can use two dyes to match colors, never use three dyes to make it easy to control the color and light. color. For example, if black can be combined with blue, do not use red, yellow, and blue.
When combining colors, equal amounts of the three primary colors are mixed to produce black.
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