Free Download Color Chemistry Zollinger Pdf Programs
Free radicals are generated by light activation and then rapidly quenched and deactivated by oxygen during the initial, inhibition phase of printing. For the material to begin to crosslink at a given position within the volume, oxygen must be sufficiently depleted locally.
Main article: The majority of natural dyes are derived from plant sources:,,,, and,,. Most dyes are synthetic, i.e., are man-made from petrochemicals. Other than pigmentation, they have a range of applications including, optical media () and (). History [ ] dyeing dates back to the period. Throughout history, people have dyed their textiles using common, locally available materials. Scarce dyestuffs that produced brilliant and permanent colors such as the natural invertebrate dyes and crimson were highly prized luxury items in the ancient and medieval world.
Plant-based dyes such as,,, and were important trade goods in the economies of Asia and Europe. Across Asia and Africa, patterned fabrics were produced using techniques to control the absorption of color in piece-dyed cloth.
Dyes from the such as and were brought to Europe by the treasure fleets, and the dyestuffs of Europe were carried by colonists to America. Dyed fibers have been found in the in a prehistoric cave dated to 36,000.
Evidence shows that, particularly in and, has been widely carried out for over 5,000 years. Early dyes were obtained from, or sources, with no to very little processing. By far the greatest source of dyes has been from the, notably roots, berries, bark, leaves and wood, only few of which are used on a commercial scale. The first synthetic dye,, was discovered by in 1856. Dyes are classified according to their solubility and chemical properties.
Are - dyes that are applied to such as,, and modified using neutral to acid dye baths. Attachment to the fiber is attributed, at least partly, to salt formation between anionic groups in the dyes and groups in the fiber. Razrabotki zanyatij shkola buduschego pervoklassnika. Acid dyes are not substantive to fibers. Most synthetic food colors fall in this category. Examples of acid dye are Alizarine Pure Blue B,, etc. Basic dyes are water-soluble dyes that are mainly applied to, but find some use for wool and silk.
Usually is added to the dye bath to help the uptake of the dye onto the fiber. Basic dyes are also used in the coloration of. Direct or is normally carried out in a neutral or slightly dye bath, at or near, with the addition of either (NaCl) or (Na 2SO 4) or (Na 2CO 3). Direct dyes are used on, paper,, wool, silk. They are also used as and as. Require a, which improves the fastness of the dye against water,. The choice of mordant is very important as different mordants can change the final color significantly.
Most natural dyes are mordant dyes and there is therefore a large literature base describing dyeing techniques. The most important mordant dyes are the synthetic mordant dyes, or chrome dyes, used for wool; these comprise some 30% of dyes used for wool, and are especially useful for black and navy shades. The mordant is applied as an after-treatment. It is important to note that many mordants, particularly those in the heavy metal category, can be hazardous to health and extreme care must be taken in using them. Are essentially insoluble in water and incapable of dyeing fibres directly. However, reduction in produces the water-soluble of the dye.
This form is often colorless, in which case it is referred to as a, and has an affinity for the textile fibre. Subsequent reforms the original insoluble dye. The color of denim is due to, the original vat dye. Utilize a attached to a that is capable of directly with the fiber substrate. The bonds that attach reactive dye to natural fibers make them among the most permanent of dyes.
'Cold' reactive dyes, such as,, and, are very easy to use because the dye can be applied at room temperature. Reactive dyes are by far the best choice for dyeing and other fibers at home or in the art studio. Were originally developed for the dyeing of, and are water-insoluble.
The dyes are finely ground in the presence of a dispersing agent and sold as a paste, or spray-dried and sold as a powder. Their main use is to dye, but they can also be used to dye nylon,, and acrylic fibers. In some cases, a dyeing of 130 °C (266 °F) is required, and a pressurized dyebath is used. The very fine particle size gives a large surface area that aids dissolution to allow uptake by the fiber. The dyeing rate can be significantly influenced by the choice of dispersing agent used during the grinding. Azoic dyeing is a technique in which an insoluble is produced directly onto or within the fiber.
This is achieved by treating a fiber with both diazoic and coupling. With suitable adjustment of dyebath conditions the two components react to produce the required insoluble azo dye. This technique of dyeing is unique, in that the final color is controlled by the choice of the diazoic and coupling components. This method of dyeing cotton is declining in importance due to the toxic nature of the chemicals used. Are inexpensive dyes used to dye cotton with dark colors. Dyeing is effected by heating the fabric in a solution of an organic compound, typically a nitrophenol derivative, and sulfide.