Dyeing Theory--Color Definition

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Humans have the desire to reflect the diversity of the natural world in their clothing. The wish to color clothing materials in order to satisfy this desire led to the development of dyeing techniques. It is an undeniable fact that today, the dyeing industry holds a very important position. Clothing is often tailored to meet needs by being given appropriate colors, patterns, shapes, and through dyeing. A certain understanding of basic sciences and common knowledge is necessary regarding the purposes of dyeing processes, the elements that make up these processes, the preparations before dyeing operations, and dyeing theory. To improve the effectiveness of dyeing processes, the development of new dyeing methods relies on a solid foundation in basic sciences and common knowledge concerning the materials used in dyeing, such as raw fibers, dyes, auxiliaries, and dyeing equipment, as well as related aspects. Only by combining this knowledge with laboratory work can one gain a deeper understanding of dyeing processes. In ancient human relics, colors were used quite early on, but the science of color only entered a new era after Newton discovered that sunlight, when passed through a prism, produced a spectrum of seven colors. During the 16th and 17th centuries, numerous studies were conducted on the reflection and refraction of light; first, the color theory of the German physicist Ostwald was developed, and in the 20th century, Munsell from the United States made further contributions, thus laying the foundation for research on color. 　 Around us in life, there are various colors present in plants and animals in the natural world. So what is \"color\"? Simply put, ‘when light hits an object, it stimulates the visual nerves, resulting in the perception of color.’ 』. The definition of color also varies depending on the role and purpose: (1) Chemists: the properties of dyes, pigments, and other substances. Scope of use: manufacturers of pigments, paints, dyes, etc., as well as users. (2) Physicist: A certain phenomenon in the field of optics. Application range: Optical instrument manufacturing industry. (3) Psychologists, physiologists: Refer to consciousness as perceived by the observer. No matter which role you play, if you want to understand colors, you must gain a deeper understanding of the various relationships within color systems: (a) the three elements that make up color: These three elements include the substance being observed, the presence of light, and the observer’s perception. It is simply because when there is no matter or light present, it is as if you are in a dark room where you cannot perceive colors; likewise, if you close your eyes, I believe you will also be unable to perceive colors. Therefore, to gain a deeper understanding of the components of color, one might start by examining the relationship between objects and color, light sources and color, and observers and color. 　 (b) Light and color perception: Although human eyes vary in sensitivity from person to person ； Yet human visual color perception remains an extremely sophisticated color-measuring device, and for such perception the presence of a light source is necessary; in the case of sunlight, there are various types of light radiation. And it is an electromagnetic wave. 　　Within the electromagnetic spectrum, the wavelength of visible light covers only a very narrow range, approximately 380nm to 760nm (1nm = 10-9m). The corresponding colors are purple for 380nm to 430nm, blue for 430nm to 485nm, yellow for 485nm to 570nm, orange for 585nm to 610nm, and red for 610nm to 760nm. Since individual perceptions of light vary, the range of 380nm to 760nm is generally considered to be the visible wavelength range. The relationship between light wavelength and color: Light wavelength and brightness: The spectra of sunlight have different levels of brightness depending on their wavelength. In the visible range, the central part of the soap is brighter, while the ends are weaker. What the eye perceives in terms of wavelength includes brightness, as well as differences between light and dark areas. For example, in bright light, yellow-green at 555nm is the brightest, while in dark light, blue-green at 510nm has the highest brightness. This is called the Purkinje phenomenon. Additive mixing and subtractive mixing: When colors are mixed, an increase in light intensity generally results in a brighter appearance. This mixing of colors is known as additive mixing or positive mixing (Additive Mixture). When dyes or pigments are mixed, the color usually darkens, a phenomenon known as subtractive mixing or negative mixing (Subtractive Mixture). When using the 3 primary colors for subtractive mixing, if the absorption of each color is appropriate, the result will be black ； In the case of additive color mixing, if the intensity of the light is appropriate, what is seen in the end will be bright white light. Visual perception of the human eye: The colors perceived by the human eye can generally be divided into two main categories, as shown in the table below: ┌ White ┌ Achromatic colors ┼ Gray 　│ └ Black 　 Colors│ 　 │ ┌ Pure colors └ Colored colors │ 　 └ Other common colors 　 　According to physical principles, white, gray, and black cannot be considered colors. White light consists of the vibrations of monochromatic lights of various wavelengths, that is, a quantitative mixture of colored lights, and represents a unified complex. Since total physical reflection has occurred, of course our eyes cannot detect it; it really cannot be considered a color. Black is an external stimulus that cannot in any way match the state of our eyes. In other words, if black cannot be contrasted with the surrounding objects, then black itself has no meaning at all. (c) The three primary colors of light and color: According to the Young-Helmholtz hypothesis, there are three fundamental colors that give rise to visual perception. Light reaches the optic nerve, stimulating the brain and thereby producing the sensation of color. These three spectral components are the sensations of red, green, and blue; these are known as the three primary colors of light. The reason why they are called the three primary colors of light is that mixing the red, green, and blue primary lights results in white. The reflection or transmission of light by other objects combines the visible colors red, yellow, and blue to form black, which are considered the primary colors. In applications involving pigments as well, mixing of the three primary colors—red, yellow, and blue—is generally used; as a result, the reflected light is reduced, yielding colors that are black or near-black in hue. When two of the primary colors of pigments—red, yellow, and blue—are mixed together, colors such as green, purple, and orange are produced; these are known as secondary colors. It is now denoted by the codes yellow (Y), red (R), and blue (B). The three attributes of the secondary color derived from Y + R = O(d) are as follows: Colors have three important sensory characteristics, which are also the three attributes of color; these will be briefly described here. Hue: Hue is a name used to distinguish different colors, such as red, yellow, blue, etc. It is called hue because it indicates the differences in appearance. Hue and the intensity of color have nothing to do with lightness or darkness. However, all colored substances possess a hue, while black, gray, and white lack color, and thus have no hue. Brightness (Brilliance or value): Also known as lightness, it actually refers to the lightness or darkness of a color; this property exists in both colored and colorless colors. Chroma: Refers to the intensity of a color; it can also be described as the saturation of a color, indicating whether the color is pure or not. Pure colorfulness exhibits its inherent properties, with no mixture of black or white; it is a color at full saturation, also known as a pure color. Chroma can be regarded as a way of indicating, for the same hue, the degree to which equal luminance is distant from gray. With a chroma at its extreme limit, it can be considered a monochromatic light of the spectrum; such a color does not exist in actual objects. (e) Representation of colors: The use of colors has a long history, with traditional names being used in the past, such as gold and silver. As society evolved and more colors emerged, traditional naming methods became insufficient to accurately describe them. Later, color charts and color samples were utilized, but these could easily get dirty or fade. Thus, more scientific and systematic approaches based on optical research were developed. (1) Qualitative representation method—color name method. (2) Quantitative representation method—1. Sensory method (three-property method). 2. Physical methods. The methods of representing color are often applied in automation in conjunction with color measurement techniques.