Effect of ammonia on madder‐dyed natural protein fiber

Abstract

Abstract Of all the beautiful reds in nature, the only one vegetable source of good dyes ever discovered by man is madder. In this research natural protein fibers (i.e., wool yarns) were dyed with madder and then treated with different ammonia solutions. A UV–visible spectrophotometer was used to measure the absorbency of the remaining ammonia solution. The absorption curves showed the absorption transfer to the visible region. FTIR spectroscopy studies indicated that the changes in intensity at the peaks occurred when the madder‐dyed yarns were treated with ammonia solutions. The results of color measurement in the CIELAB system showed that the darkness of samples increased with an increase in the ammonia percentage in the solution. The vertical wicking test was also carried out on the madder‐dyed yarns and the ammonia‐treated samples. The results showed that the ammonia treatment causes a decrease in the wicking rate. A change of color was observed on the dyed samples when wash‐fastness tests were carried out. The results of light‐fastness tests showed more fading of the madder‐dyed yarns after ammonia treatment. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 2704–2710, 2004