Fabric yellowing

Uncoated silk fabric yellowed on exposure to light. 

There are also serious side effects to fabric physical properties from flame-retardant finishing that must be recognised, often caused by the high application levels of the flame retardants. Harsh hand, loss of tensile suength and colour effects (fabric yellowing and dye shade changes) are common problems with durable flame-retardant finishes for cotton. The combination with other finishes, such as softeners, easy-care and repellent finishes, must be carefully tested. The flame retardancy of the multi-purpose finish is more often reduced than it is acceptable. 

The amine salt catalysts are nearly colorless and exhibit little tendency to turn yellow in storage. Nor do they turn the fabric yellow or otherwise affect its color. The range in base strengths of the amines and the choice of acid for the salt permits tailoring the activity of the catalysts to provide the shelf stability and curing rate required. 

Use To form metal by reduction, alloys, preparation of tungstates for X-ray screens, fireproofing fabrics, yellow pigment in ceramics. 

Most generally, deionized water should be used to formulate fabric softeners. In this way a possible cause of electrolyte variation due to water quality is eliminated. Moreover, it is a way of avoiding the presence of ferric ions, which can cause fabric yellowing. Appropriate treatment of water helps eliminate the initial contamination of the product. 

Cotton Incorporated, 2002. Overview of Fabric Yellowing. Cotton Incorporated, Cary, NC. Available at http //www.cottoninc.com/product/Tech-Assistance-Training/Technical Bulletins/ (accessed 07.02.13). 

The reducing action of sulphurous acid and sulphites in solution leads to their use as mild bleaching agents (for example magenta and some natural dyes, such as indigo, and the yellow dye in wool and straw are bleached). They are also used as a preservative for fruit and other foodstuffs for this reason. Other uses are to remove chlorine from fabrics after bleaching and in photography. 

Blueing agents, which are dyes, provide another approach to maintaining fabric whiteness by a mechanism in which a yellow cast of washed fabrics is covered by the blue dye. Since this approach reduces reflectance, it is less desirable than the use of fluorescent whitening agents that increase reflectance. 

In addition to the health risks, nitrogen dioxide in reaction to textile dyes can cause fading or yellowing of fabrics. Exposure to nitrogen dioxide can also weaken fabrics or reduce their affinity for certain dyes. Industry has devoted considerable resources to developing textiles and dyes resistant to nitrogen oxide exposure. 

Canada, are examples. These reactors do not use ordinai y water for the moderator. Most nuclear fission reactors use ordinaiy water for a moderator which requires that the fuel he about 3 percent and about 97 percent U. Achieving this enrichment requires that the solid uranium compounds in the yellow cake be converted to gaseous uranium hexafluoride (UF,). Following enrichment, gaseous UF is converted to solid uranium oxide (UO,) for fabrication of fuel elements for a nuclear reactor. 

From the perspective of the strategies aimed at fabrication of efficient blue LEDs, the results outlined above regarding yellow LPPP light emitting diodes are, nevertheless, unsatisfactory. In order to prepare blue LEDs from LPPP materials, it is necessary to efficiently mask out or suppress the dominant yellow aggregate emission. 

Some laundry detergents contain optical brighteners. These are fluorescent dyes that glow blue-white in ultraviolet light. The blue-white color makes yellowed fabrics appear white. 

Safflower, also known as bastard saffron, is a yellow dye that has been used for well over three millennia, having been identified in fabrics from the Egyptian twelfth dynasty. It is derived from the safflower plant, carthamus tinctoria, native to southern Asia and the Middle East. The coloring matter in the plants is a mixture of two components one is yellow, known as safflower yellow B the other, carthamin, is red. Safflower yellow B dissolves in water when fresh safflower flowers are washed with acidulated water. Evaporating the water from the filtered solution leaves the dye as a residue in the form of a powder. Following removal of the yellow component, the red constituent of safflower, carthamin, can be extracted from the flowers by washing them with hot water. In the East, carthamin was widely used in the past, mainly for making cosmetic preparations. 

Yellowing can occur with quaternary cationic softeners and this limits their use on white fabrics. This problem can be overcome to some extent, provided drying or fixation temperatures are not too high, using so-called pseudo-cationic softeners [482]. These products are analogous to the so-called weakly cationic surfactants described in section 9.5. 

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