Colorcast dyes software#Sulfur dyes are widely used for navy blue and dull green shades and are the industry standard for black.SilverFast has recently updated their scanning software from v. Lightfastness is poor for the light shades but good for the darker shades. Sulfur dyes tend to be inexpensive, but are sensitive to chlorine and are subject to color loss with abrasion, which leads to poor crock fastness. Compared with vat dyes, they are easier to reduce but harder to oxidize. Sulfur dyes are similar to vat dyes in that they have to be made soluble before they can be applied. In contrast to direct dyes, vat dyes produce good wash fastness. Once inside the fiber, vat dyes are oxidized back into an insoluble form. Vat dyes have no initial affinity for cotton and need to be changed chemically (or reduced) to make them soluble and able to adsorb to and diffuse into the fiber. Direct dyes are especially useful for pastel shades and lightfastness. However, direct dyes have limited brightness and poor chlorine fastness, and they require after-treatments to achieve adequate wash fastness.īecause direct dyes are attached to cotton fiber by weak forces, they are very sensitive to temperature during the dyeing process. Direct dyes are easy to apply, so dye cycles tend to be short and economical, and a wide range of colors can be applied. Hydrolysis must be controlled for dye optimization.Ī wide range of reactive dye chemistries is available, resulting in a range of performance attributes.ĭirect dyes are commonly used for cotton. Reactive dyes are subject to hydrolysis, which is the chemical reaction of the dye with the water. Which dyestuff you choose depends on the desired look (shade, color gamut, brightness) and any application issues (process flexibility, cycle time) you may experience.įiber-reactive dyes form strong covalent bonds with cellulosic fibers, which result in good wash fastness. The absorption and diffusion of dye is also known as the exhaustion of the dye. When you watch a dye bath in progress, you can see how the substrate becomes darker in shade while the bath becomes clearer and lighter. To increase colorfastness and obtain consistent shades, some type of after scouring or clean up is required to get the unfixed dye off the surface of the substrate. Once inside, dyes level out and are then are fixed to the fiber. Dyes are adsorbed to the surface of the substrate and diffuse into the fiber. In the initial phase, a substrate is placed in a medium, most often water, to which dyestuffs and auxiliary chemicals have been added. Once inside the fiber, dyes migrate (or level out) and are then fixed to the fiber. Dyes are then adsorbed to the surface of the substrate and slowly diffuse into the fiber. First, a substrate is placed in a medium, most often water, to which dyestuffs and auxiliary chemicals have been added. There is more to dyeing than obtaining the desired shade-the color must be durable and the dye must exhibit good fastness to future wet treatments and it is critical that the color be consistent from yard to yard, piece to piece, lot to lot, and from lab to production.ĭyeing a substrate involves several basic stages or steps. To take the bias out of an individual observation, computer shade matching can be employed because a shade can be issued a set of numerical values and stored in the computer, there is less handling of the fabric and various light sources can be used to compare under different conditions. So standardized lighting sources should be used. They think they are looking at the same object but they may not be because the light or illumination may be different. Observer (may be a person or an instrument such as a spectrophotometer)Īs two people at different locations, the supplier and the customer may try to emulate a standard shade given by a supplier.Object (may be a fiber, a yarn, fabric, or even a garment).How the color of a dye is perceived is dependent on three things:
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