Blue is one of the three primary colours in the RYB colour model, as well as in the RGB (additive) colour model. It lies between violet and cyan on the spectrum of visible light. The eye perceives blue when observing light with a dominant wavelength between approximately 450 and 495 nanometres. Most blues contain a slight mixture of other colours; azure contains some green, while ultramarine contains some violet. The clear daytime sky and the deep sea appear blue because of an optical effect known as Rayleigh scattering. An optical effect called Tyndall effect explains blue eyes. Distant objects appear more blue because of another optical effect called aerial perspective.
Cyan is the color between green and blue on the visible spectrum of light. It is evoked by light with a predominant wavelength between 490 and 520 nm, between the wavelengths of green and blue.
A dye is a colored substance that chemically bonds to the substrate to which it is being applied. This distinguishes dyes from pigments which do not chemically bind to the material they color. Dye is generally applied in an aqueous solution, and may require a mordant to improve the fastness of the dye on the fiber.
Indigo is a deep color close to the color wheel blue, as well as to some variants of ultramarine, based on the ancient dye of the same name. The word "indigo" comes from the Latin for Indian as the dye was originally exported to Europe from India.
Violet is the color of light at the short wavelength end of the visible spectrum, between blue and invisible ultraviolet. It is one of the seven colors that Isaac Newton labeled when dividing the spectrum of visible light in 1672. Violet light has a wavelength between approximately 380 and 435 nanometers. The color's name is derived from the violet flower.
Magenta is a color that is variously defined as purplish-red, reddish-purple or mauvish-crimson. On color wheels of the RGB (additive) and CMY (subtractive) color models, it is located exactly midway between red and blue. It is one of the four colors of ink used in color printing by an inkjet printer, along with yellow, black, and cyan, to make all other colors. The tone of magenta used in printing is called "printer's magenta". It is also a shade of purple.
A pigment is a colored material that is completely or nearly insoluble in water. In contrast, dyes are typically soluble, at least at some stage in their use. Generally dyes are often organic compounds whereas pigments are often inorganic compounds. Pigments of prehistoric and historic value include ochre, charcoal, and lapis lazuli.
Photographic paper is a paper coated with a light-sensitive chemical formula, like photographic film, used for making photographic prints. When photographic paper is exposed to light, it captures a latent image that is then developed to form a visible image; with most papers the image density from exposure can be sufficient to not require further development, aside from fixing and clearing, though latent exposure is also usually present. The light-sensitive layer of the paper is called the emulsion. The most common chemistry was based on Silver halide but other alternatives have also been used.
Staining is a technique used to enhance contrast in samples, generally at the microscopic level. Stains and dyes are frequently used in histology and in the medical fields of histopathology, hematology, and cytopathology that focus on the study and diagnoses of disease at a microscopic level. Stains may be used to define biological tissues, cell populations, or organelles within individual cells.
Subtractive color or subtractive color mixing predicts the spectral power distribution of light after it passes through successive layers of partially absorbing media. This idealized model is the essential principle of how dyes and inks are used in color printing and photography where the perception of color is elicited after white light passes through microscopic "stacks" of partially absorbing media allowing some wavelengths of light to reach the eye and not others.
A color term is a word or phrase that refers to a specific color. The color term may refer to human perception of that color which is usually defined according to the Munsell color system, or to an underlying physical property. There are also numerical systems of color specification, referred to as color spaces.
Bromophenol blue, albutest is used as a pH indicator, an electrophoretic color marker, and a dye. It can be prepared by slowly adding excess bromine to a hot solution of phenolsulfonphthalein in glacial acetic acid.
Fluorescein angiography (FA), fluorescent angiography (FAG), or fundus fluorescein angiography (FFA) is a technique for examining the circulation of the retina and choroid using a fluorescent dye and a specialized camera. Sodium fluorescein is added into the systemic circulation, the retina is illuminated with blue light at a wavelength of 490 nanometers, and an angiogram is obtained by photographing the fluorescent green light that is emitted by the dye. The fluorescein is administered intravenously in intravenous fluorescein angiography (IVFA) and orally in oral fluorescein angiography (OFA). The test is a dye tracing method.
In many languages, the colors described in English as "blue" and "green" are colexified, i.e. expressed using a single cover term. To describe this English lexical gap, linguists use the portmanteau word grue, from green and blue, a term coined by the philosopher Nelson Goodman—with a rather different meaning—in his 1955 Fact, Fiction, and Forecast to illustrate his "new riddle of induction". The alternative, bleen, is not really used.
Vat dyes are a class of dyes that are classified as such because of the method by which they are applied. Vat dyeing is a process that refers to dyeing that takes place in a bucket or vat. The original vat dye is indigo, once obtained only from plants but now often produced synthetically.
Bromocresol green (BCG) is a dye of the triphenylmethane family. It belongs to a class of dyes called sulfonephthaleins. It is used as a pH indicator in applications such as growth mediums for microorganisms and titrations. In clinical practise, it is commonly used as a diagnostic technique. The most common use of bromocresol green is to measure serum albumin concentration within mammalian blood samples in possible cases of kidney failure and liver disease.
A solvent dye is a dye soluble in organic solvents. It is usually used as a solution in an organic solvent.
Color motion picture film refers both to unexposed color photographic film in a format suitable for use in a motion picture camera, and to finished motion picture film, ready for use in a projector, which bears images in color.
The sokutai (束帯) is a traditional Japanese outfit worn only by courtiers, aristocrats and the emperor at the Japanese imperial court. The sokutai originated in the Heian period, and consists of a number of parts, including the ho, shaku (笏), a flat ritual baton or sceptre, and the kanmuri (冠), a cap-shaped black lacquered silk hat with an upright pennon decorated with the imperial chrysanthemum crest.
Alcian blue is any member of a family of polyvalent basic dyes, of which the Alcian blue 8G has been historically the most common and the most reliable member. It is used to stain acidic polysaccharides such as glycosaminoglycans in cartilages and other body structures, some types of mucopolysaccharides, sialylated glycocalyx of cells etc. For many of these targets it is one of the most widely used cationic dyes for both light and electron microscopy. Use of alcian blue has historically been a popular staining method in histology especially for light microscopy in paraffin embedded sections and in semithin resin sections. The tissue parts that specifically stain by this dye become blue to bluish-green after staining and are called "Alcianophilic". Alcian blue staining can be combined with H&E staining, PAS staining and van Gieson staining methods. Alcian blue can be used to quantitate acidic glycans both in microspectrophotometric quantitation in solution or for staining glycoproteins in polyacrylamide gels or on western blots. Biochemists had used it to assay acid polysaccharides in urine since the 1960s for diagnosis of diseases like mucopolysaccharidosis but from 1970's, partly due to lack of availability of Alcian and partly due to length and tediousness of the procedure, alternative methods had to be developed e.g. Dimethyl methylene blue method.
