Coffee Stains on Nylon

Although the resistance to staining by synthetic food colorants has been the main thrust of the commercial development of stain-resistant carpets, coffee has remained the worst offender [19]. Coffee is a very popular beverage and coffee stains on textiles are common, especially on tablecloths and carpets. 

The interaction between coffee and fibers depends on the nature of the fibers. The affinity of coffee stain to fibers, indicated by resistance to detergency, increases in the order polyester cotton nylon [20]. The coffee stain has very little affinity to polyester fibers but adheres to cotton and most firmly to nylon. The high affinity of coffee to nylon is a formidable challenge to the stain-resist finishing. 

Contrary to a common belief, coffee stain is not caused mainly by colored 

Although coffee has been consumed for centuries, the chemical composition of coffee is not completely known. The composition of coffee is complex, over 700 components have been detected so far [21-24]. 

Roasted coffee contains a substantial amount of colored matter brown to black pigments, polymers, and water-soluble colored substances. The composition of the colored species is largely unknown. 

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In the absence of a stain-resist finish, adsorption of coffee stain on nylon fibers is rapid, followed by a slow diffusion of some of the colored species into fibers. The sorption of coffee by nylon fibers is accelerated by heat (Fig. 14.6). Because coffee is usually consumed hot, spilled coffee is a real challenge to a stain-resistant finish. 

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