Investigations into the Continuous Dyeing of Wool

Milligan, Brian

doi:10.1111/j.1478-4408.1961.tb02429.x

Cited by 14 publications

(11 citation statements)

References 4 publications

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“…In his review, Milligan [56] listed six plausible processes to explain the rapid photoyellowing of FWAtreated wool: -photodecomposition of the FWA leads to loss of whitening power; -FWA photoproducts quench the fluorescence of the residual FWA leading to further loss of whitening power; -the whitener decomposes to form yellow products; -the whitener or its photoproducts react with wool to produce yellow products; -the whitener increases the rate of the normal yellowing mechanism that occurs in the absence of FWA and; -the FWA initiates new yellowing reactions within the fibre.…”

Section: Photoyellowing Of Wool Treated With Fluorescent Whitening Agmentioning

confidence: 99%

Photoyellowing of wool. Part 2: Photoyellowing mechanisms and methods of prevention^†

Millington

2006

Coloration Technology

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Part 1 of this review discussed the effects of light on wool keratin and the factors that affect the rate of photoyellowing. Part 2 describes the various photochemical mechanisms that have been proposed to account for photoyellowing of wool by sunlight, and focuses in particular on their strengths and weaknesses. The mechanisms involved in the rapid photoyellowing of wool treated with a fluorescent whitening agent are described in some detail since this remains a serious commercial problem. Existing methods for reducing the rate of wool photoyellowing are reviewed, together with a discussion of the remaining scientific and technical challenges to achieve bright, white wool fabrics and garments of high photostability.Scheme 1

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Section: Photoyellowing Of Wool Treated With Fluorescent Whitening Agmentioning

confidence: 99%

Photoyellowing of wool. Part 2: Photoyellowing mechanisms and methods of prevention^†

Millington

2006

Coloration Technology

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“…Useful reviews of this subject have been published by Milligan [46], MacLaren and Milligan [47] and Nicholls 1481 * There have been numerous studies of the yellowing of wool and silk by U.V. light [49-541, and most of these have attributed the phenomenon to the amino acid tryptophan.…”

Section: The Chemical Basis Of Photoyellowingmentioning

confidence: 99%

The Yellowing and Bleaching of Wool

Duffield¹,

Lewis²

1985

Review of Progress in Coloration and Related Topics

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The yellowing of wool is a complex phenomenon which is induced by a variety of agencies such as light, heat and aqueous chemical reactions. Yellowing of wool by light depends critically on the wavelength distribution of the light (u. v. region), humidity and the type of prebleach given to the wool; if fluorescent whitening agents (FWAs) are employed in the bleaching process then the sensitivity to photo‐yellowing is drastically increased. The copious amount of work carried out to overcome this complex situation will be summarised and the important role of the aromatic indole amino acid, tryptophan, will be detailed. In contrast to photoyellowing, exposure of wool to visible blue light (maximal effect 420–450 nm) promotes photobleaching of the yellow pigments, giving rise to complaints of colour change, especially in wool products dyed to pastel colours. To remove natural yellowness, chemical bleaching of wool is usually carried out by using hydrogen peroxide, the usage of which should be carefully controlled because of its fibre damaging characteristics. Optimisation of wool peroxide bleaching procedures has therefore been the subject of much work and these studies will be reviewed. Bleaching of wool with reducing agents is often practised either as an alternative to peroxide bleaching or more usually as an aftertreatment of peroxide‐bleached wool to improve the whiteness and stability to light. Trade practice in the field of wool bleaching has recently been critically reviewed; the results and recommendations of this assessment will be given. More recently, significant progress has been made in the field of selective dark fibre bleaching and in the bleaching of heavily pigmented wools (e.g. karakul) using methods based on ferrous ion mordanting.

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“…Several yellow chromophores have previously been identified as the photo-oxidation products of aromatic amino acid residues in the keratin protein [5]. More recently it has been suggested that chromophores are also produced that originate from the FWA itself [6].…”

Section: Introductionmentioning

confidence: 99%

Improving the photostability of whitened wool by applying an anti‐oxidant and metal chelator rinse

Millington

2006

Coloration Technology

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The combination of a water‐soluble anti‐oxidant with a metal‐chelating agent improved the wet and dry photostability of wool treated with a fluorescent whitening agent (FWA) significantly when used as a rinse treatment after FWA application. The most effective anti‐oxidants identified were l‐ascorbic acid and N‐acetyl cysteine. Oxalic acid was the most effective metal chelator, capable of limiting visible yellowing under both wet and dry conditions, and its use as a rinse treatment on FWA‐treated wool also improved its initial whiteness. Although rinse treatments containing l‐ascorbic acid provided a high level of photoprotection when wool samples were examined immediately after exposure to light, it was unsatisfactory due to the slow reaction of its oxidation product dehydroascorbic acid with free amino groups in wool to produce pink chromophores after standing for a few days. These pink chromophores slowly turned yellow over several weeks.

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Investigations into the Continuous Dyeing of Wool

Cited by 14 publications

References 4 publications

Photoyellowing of wool. Part 2: Photoyellowing mechanisms and methods of prevention^†

Photoyellowing of wool. Part 2: Photoyellowing mechanisms and methods of prevention^†

The Yellowing and Bleaching of Wool

Improving the photostability of whitened wool by applying an anti‐oxidant and metal chelator rinse

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Investigations into the Continuous Dyeing of Wool

Cited by 14 publications

References 4 publications

Photoyellowing of wool. Part 2: Photoyellowing mechanisms and methods of prevention†

Photoyellowing of wool. Part 2: Photoyellowing mechanisms and methods of prevention†

The Yellowing and Bleaching of Wool

Improving the photostability of whitened wool by applying an anti‐oxidant and metal chelator rinse

Contact Info

Product

Resources

About

Photoyellowing of wool. Part 2: Photoyellowing mechanisms and methods of prevention^†

Photoyellowing of wool. Part 2: Photoyellowing mechanisms and methods of prevention^†