Thermochromicity in Wool Dyed with 6-Bromoindigo Depends on the Presence and Identity of a Solvent

The thermochromic effect of wool dyed with 6-bromoindigo was found to depend on both heat and a solvent. fabric must be immersed in solvent while heating for color change from purple blue occur. Ethanol the most effective causing change. Water as well. 1-Butanol caused slight change, toluene completely ineffective. These results are interpreted interaction surface adsorbed dye molecular aggregates, changes size large red aggregates smaller ones. mildest conditions immersion water at 60 °C, so easily obtained that it is possible ancient dyers knew this finishing process their dyeing, or avoid post-dyeing treatment.