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United States Department of Agriculture

Agricultural Research Service

Title: Low Temperature Dyeing of Wool Processed for Shrinkage Control

Authors
item Cardamone, Jeanette
item Damert, William

Submitted to: Textile Research Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: July 6, 2005
Publication Date: January 1, 2006
Citation: Cardamone, J.M., Damert, W.C. 2006. Low temperature dyeing of wool processed for shrinkage control. Textile Research Journal. 76(1):78-85.

Interpretive Summary: Dye fabrics must be dyed at high temperatures of 90º-120°C to ensure complete dye uptake and dyeing times can extend to 1 ½ hours. The fabrics are usually yellowed and weaker, and harsh to the touch. After applying the ERRC process designed to whiten, biopolish and shrinkproof wool fabrics, the fabrics are bright, soft, and dimensionally stable to machine washing, and we found that dyeing times were shortened to 30 to 50 minutes and dyeing was complete within a low temperature dyeing range of 30°-55ºC. The graphs of dye uptake with time showed that fabrics treated with only the first stage of treatment dyed similarly to the untreated fabrics and those treated with the full treatment dyed differently to indicate changes in wool's fiber structure that were shown in photomicrographs. Photomicrographs revealed that the full ERRC process erodes the fiber scales to allow for relatively quick and uniform dye distribution within the fiber. Dyeing ERRC-processed wool textiles at lower temperatures will provide cost savings, less damage, the possibility of brighter shades, and less deterioration for improved textile performance.

Technical Abstract: Conventional dyeing of wool fabrics with acid dyes generally requires high temperatures of 90º-120° and extended dyeing times of up to 120 minutes to achieve complete exhaustion. Consequently fabric properties can deteriorate with negative implications for consumer selection, wear, and care. The ERRC process for whitening, biopolishing, and shrinkage control was applied to untreated wool knit fabrics in two-steps: pretreatment with dicyandiamide and gluconic acid in alkaline peroxide, followed by treatment with sodium sulfite and serine protease. Untreated and pretreated fabrics exhibited sigmoidal dyeing behavior whereas pretreated/treated fabrics exhibited exponential dyeing behavior. Typically, the dyebaths of the untreated fabrics exhausted within 60-120 minutes at 90º-120°C. However, the dyebaths of fabrics after pretreatment alone exhausted within 50-60 minutes at 55º-60°C. The dyebaths of fabrics receiving the full pretreatment/ treatment exhausted within 30-50 minutes at 30°-55ºC. Low temperature dyeing with reduced dyeing times was attributed to changes in wool fiber morphology as documented by confocal fluorescent and scanning electron microscopies. Dyeing ERRC-processed wool textiles at lower temperatures will provide cost savings, less damage, the possibility of brighter shades, and less deterioration for improved textile performance.

Last Modified: 12/21/2014
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