Chrome Dyes on Wool

Chrome dyes (see Section 3.11.2) are selected acid dyes that form complexes with chromium ions. With complex formation a strong bathochromic shift of shade occurs. In addition, as a result of the superposition of several excited states, a marked dulling of the hue is observed. 

Auxiliary agents, such as ethoxylated fatly alcohols, alkylphenols, and fatty amines, can improve level dyeing. 

In the afterchroming method with chrome-developing dyes, the dyeing liquor is prepared with formic acid (pH 3.5-3.8), sodium sulfate, and an amphoteric leveling agent as a wool protectant. The process is started at 40 °C, and dissolved dye is added. The system is heated, and dyeing is performed at 90°C for 30- 

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