Color reproduction on varnished cardboard packaging by using lower ink coverages due to the gray component replacement image processing

Even in these challenging times, cardboard packaging industry is increasing its revenue with stable annual increase prediction, but customers are increasing demands on the packaging with respect to environmental protection, attractiveness, and branding. This article aims to determine the influence of image processing in terms of gray component replacement and overprint varnishing on the color reproduction on a cardboard packaging material. A test chart with tertiary colors was defined and modified by different gray component replacement levels. It was printed in accordance with ISO norm on coated and uncoated cardboard and finished by overprinting water based, offset, and UV varnish. The prepared samples were evaluated by measuring surface coverage, tone value increase (dot gain) of primary colors and calculating ΔE₀₀ of defined tertiary colors. The results showed that gray component replacement application reduces ink consumption. Higher gray component replacement applied results in lower ink surface coverage, but the decrease is also dependent on the image content. The TVI (dot gain) is significantly influenced only by applying UV varnish, resulting with higher TVI. The color differences of the tertiary colors showed that increased level of the gray component replacement applied did not cause significant color differences, even decreased color difference in some cases. Additionally, applying gray component replacement decreased color differences in “reddish” part of the gamut. This research proved that lowering the ink consumption due to the gray component replacement will not cause significant differences in the color reproduction. Furthermore, varnishing with commercial offset or water-based varnish will not cause higher deviations in color reproduction, but use of the UV varnish would.     

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.     

硫酸钴对立德粉耐光性的作用

分析和探讨了添加硫酸钴的作用及影响因素等 ,提出了加入硫酸钴的计算方法 ,使立德粉的耐光性得到提高。     

The effect of polycation on the light fastness of CI Acid Red 249

Cationic compounds are frequently used in direct dyeing processes and in ink-jet printing as dyefixing agents. In some cases, however, they can reduce the light fastness of dyes used. This report deals with the effect of a polycationic compound, Polyfix 601, on the light fastness of CI Acid Red 249, an anionic 2-phenylazo-1-naphthol dye, in aqueous solutions and in PVA films. As a comparison, the much smaller ammonium cation was used, which had no observable effect on hue or dye light fastness. However, some changes to the dye's physical properties were observed. The effect of the polycation is explained as a consequence of dye aggregation, facilitated by presence of polycation. Self-sensitised singlet oxygen seemed to play no part in dye photofading, but other oxygen species could participate in the process.     

Improving the light fastness of dyed nylon fabrics using nickel arylsulphonates

Various nickel arylsulphonates were synthesised and their protecting effects on the photofading of CI Basic Violet 3, CI Acid Red 94, CI Acid Red 87 and CI Acid Blue 74 examined on nylon fabric. The rates of photofading of the dyes were remarkably suppressed in the presence of nickel salts, while the addition of ultraviolet absorbers and conventional stabilisers afforded little retardation of the rate of fading. The antimicrobial activity against two species bacteria of nickel salts was also examined. This aftertreatment technique was shown to be safe for the environment and human health.     

The influence of a polymer substrate on the light fastness and isomerisation of some azo dyes

Poly(ethylene terephthalate) films having different morphologies have been coloured with some azo dyes. Isotropic and anisotropic films showed an inversion in dyeing behaviour as well as in light fastness, always at crystallinity β=0.5. We have interpreted the phenomenon in terms of a different localisation of the dye in going from a structure of PET corresponding to a free-volume model to a structure corresponding to a pore model. It was found that polymer morphology strongly affected dye photofading whilst the thermal cis-trans isomerisation of azo dyes in the PET matrix depended only on the amorphous region; below the glass transition temperature isomerisation proceeded in a way that was determined by the effects of restrictions in the mobility of the photochrome itself.     

A novel approach for improving the light fastness of crystal violet lactone

Colour formers are important as functional dyes for imaging and data recording systems. Metal complexes of substituted arylsulphonic acids or arylcarboxylic acids have been synthesised to prolong the life of coloured species derived from crystal violet lactone. The suppressing effect of these compounds towards photofading was investigated on cellulose. It was found that zinc and nickel salts of 2,6-dihydroxybenzoic acid and its derivatives can be applied as effective stabilisers against the fading of crystal violet lactone. The protecting effect of phenyl esters against fading was also examined.     

Effect of acylation on the dyeing and fastness properties of some azo dyes

The changes brought about by acetylation, benzoylation and terephthaloylation of some disperse dyes derived from 4–aminoazobenzene on the dyeing and fastness properties are described. Dyes substituted by benzoyl and terephthaloyl groups tended to have better light, wash and sublimation fastness on polyester. The dyes showed good build–up when these groups are coupled with an N–β–cyanoethyl group. Acylation of azo dyes resulted in poor substantivity and poor fastness properties on nylon 6.     

Microscopic-photometric measurement of polymodal clay orientation using circular-polarized light and interference colours

Orientation measurements are important in many branches of geosciences in both field and laboratory studies. For fine-grained especially clayey samples, particulate and other physical methods are unsuitable. This is because numerous individual measurements are needed for a desirable level of accuracy, and sophisticated sample preparations and equipment are required. Existing photometric techniques were evaluated. They fail to deliver circular vectorial data (both magnitude and direction) for preferred orientation, and cannot detect bimodal or polymodal patterns. A modified method is developed to overcome these pitfalls. The pertinent principles related to clay orientation in thin sections, relative retardation and interferece colours are reviewed. Spectral distributions of interference colours are calculated and plotted to facilitate the selection of a suitable wavelength to winnow the light. A sensitive-tint plate of gypsum is used to alter the relative retardation and hence the interference colours of oriented clay in thin sections. The interference colours of unlike vibration direction are separated from those of alike vibration and isotopic components (including voids) by a monochromatic filter at a chosen wavelength, and detected by a photoelectric sensor (selenium photocell). Circular-polarized light was employed to eliminate the extinction phenomenon which was regarded as unwanted noise. Details on calibration, equipment setup and procedures are given. The application of circular statistics to the orientation data is described and illustrated with results of selected specimens.     

Efficiency of ultraviolet/ozone treatments in the improvement of the dyeability and light fastness of wool

In this study, we evaluated the effect of ultraviolet/ozone treatments for different times on the characteristics of wool fabrics with respect to wettability, permeability, yellowness index, and weight loss. The beneficial effects of this treatment on dyeability, color parameters, light fastness characteristics, and the change in color difference after exposure of the treated dyed samples to artificial daylight for about 150 h was investigated. The results indicated that the improvement in wetting processes may have been due to to surface modifications; this meant that an increase in the amorphousity of the treated samples, the oxidation of the cystine linkage on the surface of the fabrics, and the formation of free‐radical species encouraged dye penetration and aggregation inside the fiber pores as well as bond formation. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 3668–3675, 2003     

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.     

Effect of the rubbing force on dry rubbing fastness with various white cloths

The rubbing‐off of dye from fabrics was investigated from a kinetic viewpoint using various white cloths under weights of 2–6 N. The natural logarithm of the rate constant of dye transfer from dyed fabric to white cloths and that of the equilibrium constant were linearly related to the reciprocal of the rubbing force, which was given by the product of the weight and the friction coefficient between the dyed fabric and white cloth. Two straight lines were obtained, in spite of the variety of white cloths used, and they converged in the low rubbing force range. The results show that the dry rubbing fastness with various white cloths is primarily influenced by the friction coefficient and rubbing force rather than by the types of textile fibre or fabric.     

Effect of observer metamerism on colour matching of display and surface colours

We studied the individual variability of asymmetric metameric colour matching between computer displays and object colour stimuli in conditions typical for the surface colour industries. Using two different computational techniques, we assessed the contribution of observer metamerism to this variability. In the studied conditions of spatially separated computer display and surface colour stimuli, this contribution was found to be insignificant for all colours but neutrals. In the chromaticness plane, the range of matches made by different observers practically coincides with the range of matches made by an individual observer. Consequently, we conclude that in the task of matching spatially separated display and surface colours, the range of matches made by a group of observers cannot be determined from variations in their colour‐matching functions, and thus the paradigm of the Standard Deviate Observer is shown to be inapplicable to the studied conditions. We suggest that individual variability in these conditions is governed by mechanisms of chromatic discrimination, and can be modeled by advanced colour difference formulae with suitably adjusted parametric coefficients. © 2008 Wiley Periodicals, Inc. Col Res Appl, 33, 346–359, 2008     

Shedding light on the colours of medieval alabaster sculptures: Scientific analysis and digital reconstruction of their original polychromy

Although medieval alabaster sculptures might appear white at present, they were colourful once, because painting and gilding the stone was an integral part of their production. This work presents the study of polychrome remnants on a selection of fourteenth century English alabasters, using multiple scientific methods (microscopy, spectroscopic and chromatographic techniques). The range of pigments identified include vermilion, red ochre, red lead, kermes, verdigris, copper resinate, azurite, lead white and carbon black. Some sophisticated decorative techniques were also observed, namely the application of translucent glazes on top of raised gilded motifs. The analysis was useful in understanding the degradation processes undergone by some materials, such as verdigris. The use of oil as binding medium for the application of the paint layers and a mordant gilding technique were determined. These findings yielded important clues towards the digital reconstruction of the original appearance of the polychrome surface, which is also presented here.     

带束层角度对轮胎印痕的影响

试验研究以锦纶帘线为胎体,以芳纶与锦纶的复合帘线为带束层的子午线轮胎,带束层角度对轮胎印痕的影响。试验结果表明：在同种条件下,随着轮胎带束层角度的变化,轮胎接地印痕、受力分布发生变化。     

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.     

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.     

Digital light processing fabrication of mullite component derived from preceramic precusor using photosensitive hydroxysiloxane as the matrix and alumina nanoparticles as the filler

By taking advantage of the low sintering temperatures of the preceramic polymers, stereolithography printed mullite components derived from preceramic polymer precursor containing alumina particles can be sintered at low temperatures. However, due to their high specific surface, nano alumina particles are difficult to be dispersed into the photocurable polysiloxane. Herein, to prepare mullite slurry, a photosensitive hydroxysiloxane was employed as the preceramic polymer matrix while γ-Al₂O₃ nanoparticle was added as the active filler. The introduction of photocurable hydroxysiloxane not only improved the homogeneity and rheological properties of mullite slurry but also shorted the ionic diffusion distance of Si-ion and Al-ion during the sintering process. Therefore, 3D mullite preceramic precursor stereolithography printed from hydroxysiloxane-Al₂O₃ slurry was endowed with a low sintering temperature around 1400 °C. During the sintering process of preceramic precursor, sintering aid AlF₃ can participate in the reaction and further promote the formulation of mullite grains.