The colors of direct dyes are duller than those provided by fiber reactive dyes, and the washfastness is poor - expect anything dyed with them to 'bleed' forever. The one advantage is that direct dyes may be more lightfast, that is, resistant to fading in the light, than fiber reactive dyes. Cotton can also be dyed with vat dyes, and azoic or naphthol dyes. Indigo is an example of this dye class. Azoic or naphthol dyes use more hazardous chemicals and are therefore much less desirable for home use.
All purpose dyes Another group of dyes is known as all-purpose, household, or union dyes.
Knutson points out that since half of the dye is thus not useful for whichever fiber you're using, you are wasting half of what you're buying, and thus wasting money, if you use these dyes. The only real advantage to these dyes is their ubiquity in grocery and drug stores, but their inadequacies have turned many people, ignorant of the alternatives, away from the art of dyeing. I cannot recommend their use. Dyes for Protein Fibers Protein fibers include silk, wool, angora, cashmere, and mohair. Silk is a special case - it can be dyed with fiber reactive dyes, using the very same recipe as cotton, or acid dyes, like the other protein fibers.