Light Fastness Of Natural Dyes Research Articles

Enhancing the light fastness of natural dyes by encapsulation in silica matrix

The study shows the possibility of improving the light fastness of natural curcumin dyes extracted from turmeric by encapsulation in silica matrix. Curcumin extracts were obtained by conventional and microwave assisted extractions. Encapsulation into a silica matrix was performed by using three different routes in the presence of NaOH, lysine or triethanol amine. The curcumin loaded silica particles were characterized by SEM, EDX, FT-IR, UV–Vis and photoluminescence spectroscopy analyses. The light fastness of the curcumin capsules was further investigated by UV–Vis spectroscopy. The color description was performed by employing the CIEL*a*b* system and the color difference was calculated. The stabilization methods lead to high encapsulation efficiencies and a very good light fastness for all samples.

Improving the Light Fastness of the Wool Dyed with Pomegranate Peels

ABSTRACT Natural dyes are highly promising alternatives; however, their use has some drawbacks such as low light fastness, color yield, and repeatability. The objective of this study is to improve the light fastness of natural dyes. For this objective, wool fabrics dyed with pomegranate peels were subjected to different chemical treatments and UV curing. An important conclusion of this work is that UV curing can significantly increase the light fastness of the fabrics dyed with pomegranate peels. Moreover, different chemical processes including optical brightening have exhibited a positive effect on the light fastness of the samples. As an example, UV light exposure of the fabric, which was mordanted with copper sulfate and treated with TiO2, resulted in an increase of the light fastness from 4–5 to 7.

Polydopamine‐coated silk yarn for improving the light fastness of natural dyes

One of the problems occasionally associated with the use of natural dyes in the dyeing of silk is the susceptibility of the dyed yarn to fading in light. While a number of approaches have been used to address this problem, the use of polydopamine (PDA), a known agent with photo‐protective properties, has not been assessed previously. In this study, silk was pretreated with nano‐particulate PDA formed in situ by oxidation of a dopamine solution, then dyed with lac dye or annatto dye as model natural dyes. Photofading rates were significantly reduced in the case of annatto‐dyed, PDA‐coated silk relative to uncoated silk, while wash fastness was unaffected and remained only moderately good. In contrast, no significant change was seen in photofading rates with treated or untreated lac‐dyed silk, and wash fastness was also unaffected. The PDA did not adversely affect resultant colour values if the concentration of the dopamine precursor was kept low. When this was done, acceptable colours were obtained in the dyed silk. Further investigation is warranted of PDA as a photofading protectant and mordant with other natural dyes on silk and other fibres.

Ascorbic acid treatment to improve the light fastness or as reducing agent on silk fabric dyed with pulverised natural dyes

Purpose This study aims to improve the natural dyeing recipe with better light fastness using ascorbic acid (vitamin C) with pulverised plant dyes. Design/methodology/approach Silk fabrics pre-mordanted with alum (aluminium ammonium sulphate) were dyed using six types of plant dyes available in Sarawak, Malaysia, namely, Engkerabai leaves (Psychotria viridiflora), Ketapang leaves (Terminalia catappa), mangrove bark (Ceriops tagal), Sepang wood (Caesalpinia sappan), mangosteen husk (Garcinia mangostana) and onion skin (Allium cepa). Then, the dyed samples were immersed in vitamin C. The dyed and vitamin C-treated silk samples were exposed to direct sunlight for 40 h to test whether vitamin C had any effect on the light fastness of the dyed samples. Findings It was found that the fabric samples using vitamin C for after-treatment, particularly Engkerabai, Ketapang, mangrove and mangosteen, exhibited better light fastness. The colours of the four samples changed and looked darker when compared to the non-treated fabric samples. However, it was observed that vitamin C had a reverse effect on Sepang wood and onion skin. The acidic aqueous solution of vitamin C discharged the dyed samples instead. Originality/value In conclusion, depending on the plant types, vitamin C can be used to improve the light fastness of natural dyes or as a reducing agent for natural dyes.

Improvement of light fastness of natural dye: effect of ultraviolet absorbers containing benzotriazolyl moiety on the photofading of red carthamin

While the contribution of ultraviolet absorbers to synthetic dyes has been investigated by several workers, there have been few studies pertaining to the use of functional ultraviolet absorbers as a means of improving the light fastness of natural dyes. In this paper, numerous potential ultraviolet absorbers were prepared to prolong the life of natural dye carthamin. The effects of these compounds in reducing photofading were examined on a polymer substrate. The use of commercial ultraviolet absorbers was not necessarily useful in improving the light fastness of the colour. However, benzophenone‐type ultraviolet absorbers containing a built‐in ultraviolet absorber moiety markedly retarded the photofading rate. It is proposed that 2,2′,4,4′‐tetrahydroxy‐5‐methylbenzotriazolylbenzophenone and its derivatives may be used as effective stabilisers in the fading of natural dyes.

An Attempt to Improve the Light Fastness of Natural Dyes (Part 2)

An Attempt to Improve the Light Fastness of Natural Dyes (Part 2)

An Attempt to Improve the Light Fastness of Natural Dyes

An Attempt to Improve the Light Fastness of Natural Dyes

Improving light fastness of natural dyes on cotton yarn

The objectives of this study were to evaluate the light fastness of selected natural dyes (madder, weld and woad) and the effect of some commonly used antioxidants and UV absorbers on the light fastness of these dyes. The photofading rate curves of madder and weld fixed on cotton correspond to type II fading rate curves described by Giles. These results are in concordance with those of Cox-Crews. The woad presents a type III fading rate curve, similar to the indigo fading rate curve presented by Cox-Crews. A poor light fastness of the three natural dyes in comparison with synthetic ones is established beyond question. Nevertheless, the use of some additives can improve this default of natural dyes. In all the cases, the use of UV absorbers or antioxidants improved the light fastness of dyed fabrics. The most effectives were the vitamin C and the gallic acid.

Improvement of light fastness of natural dyes. Part 2: Effect of functional phenyl esters on the photofading of carthamin in polymeric substrate†

The photofading behaviour of carthamin in cellulose acetate film was investigated. A contribution from singlet oxygen to that fading was suggested. Phenyl esters containing nickel sulphonate quenching groups were prepared and the protecting effect of these compounds towards the photofading of carthamin was examined in cellulose acetate film. It is proposed that nickel sulphonate derivatives of phenyl esters can be applied as effective stabilisers against the fading of natural dyes.

Improvement of the light fastness of natural dyes: the action of singlet oxygen quenchers on the photofading of red carthamin

While the contribution of singlet oxygen quenchers to synthetic dyes has been investigated previously by several workers, there have been few studies pertaining to the use of singlet oxygen quenchers as a means of improving the light fastness of natural dyes. In this paper, the influence of various additives on the photofading of carthamin has been examined in cellulose acetate film. The rate of photofading of the colour was remarkably suppressed in the presence of nickel hydroxyarylsulphonates, while the addition of UV absorbers afforded little retardation in the rate of fading.