The Measurement and Assessment of Colour Differences for Industrial Use V—The Accuracy of Visual Assessments in Relation to Industrial Colour Passing

The quantitative data available for expressing the errors associated with visual assessments, measurements and colour-difference equations have been used to calculate, for given sets of circumstances, the pass and rejection rates at various stages from the dyer to the retailer to the final customer. The main errors arise in the visual assessments and the colour-difference equations and, for the average of the available equations, these two errors are roughly comparable in magnitude. They do, however, vary with size of colour difference in different ways such that for small differences (0- 1AN40 units) the equations agree better with the true colour differences than a single visual assessment, whereas the reverse is true for large differences (above 2 AN40 units). Detailed results depend on the distribution of samples over the range of colour differences considered, together with the sizes of colour-tolerance limits set. Two initial distributions for the dyer have been assumed, one with same number of samples at all colour differences and the other simulating the distribution used in the Davidson and Friede study. For each, the results of use of a ‘low tolerance’ (0.5 AN40 unit) and a ‘high tolerance’ (1.5 AN40 units) by the dyer have been calculated. At low tolerance, the average equation provides much greater satisfaction than one assessor and improved equations will not give much more satisfaction. At high tolerance, the average equation could give greater or less satisfaction depending on the precision of the particular assessor and the exact distribution of samples to be considered, but there are considerable benefits to be gained by improvement in equation performance. Some of the likely interactions between the dyer and his customers are illustrated, showing that difficulties could arise unless there is some degree of co-operation. This is particularly true if unilateral action for equation use is taken by the retailer working to his customary tolerance limit. It would appear that the introduction of the use of an equation should first be made by the dyer, but if made by the retailer then consultation with the dyer is essential. The use of an equation by a retailer provides little benefit except in reducing dyer-retailer disputes.     

The Measurement and Assessment of Colour Differences for Industrial Use. IV—The Accuracy of Visual Assessments

The magnitude of the errors in the visual assessment of colour differences is discussed. The errors are likely to vary with the particular form of visual assessment. Methods are described for estimating visual errors from data in which the visual assessments are expressed as percentage acceptance and rank orders as well as ratios of other colour differences. The results indicate that experienced observers tend to have a greater degree of discrimination than inexperienced observers. Between-observer variation is greater than within-observer variation, suggesting that the mean of many repeat observations by a single observer may differ significantly from the mean derived from a number of different observers. For colour passing, the error of a single observer varies with the size of the colour difference and is given by the equation: σ=0.4+ 0.25 δν where δν is the true visual difference expressed in units equivalent to the average unit given by the AN40 equation.     

Publications Sponsored by the Colour Measurement Committee—V The Adams—Nickerson Colour-difference Formula*

The Adams uniform-chromaticity-scale diagram, the Adams-Nickerson uniform colour space (ANLAB) and the derived colour-difference formula are described in detail. An example showing the method of calculating colour differences is given.     

Factors Affecting Instrumental Measurement and Visual Assessment of Colour Differences

The factors affecting the instrumental measurement of colour differences are reviewed. For most types of sample the performance of modern instruments is more than adequate provided that sufficient care is taken. Problems may arise with metameric pairs and fluorescent samples. The main source of error lies in the colour–difference equations/ this is quite separate from errors due to the instrument. Problems associated with visual assessments are discussed. The use of a panel of three observers will produce more reliable results and may be preferable under certain circumstances.     

Colour Measurement — Present Position and Future Developments

Presented at a Symposium on ‘The Next Fifty Colourful Years’, held by the Huddersfield Region at Huddersfield College of Technology, on 18 October 1968, Mr G. England in the chair The contributions to colour theory and colour measurement which have been made during the last 50 years and which led directly to some industrial end-use are reviewed briefly. Some of the more important applications are discussed and the associated difficulties for extension of use are outlined. The requirements for automated, colour-monitored dyeing processes are considered generally.     

色差的测量及其不确定度的评定

介绍了颜色的测量及其表示方法,以及常用的色差计算方法。简述了不确定度的定义及评定方法。通过白色色板的测定对仪器测定色差进行了不确定度的评定。     

Colour Measurement in the Hungarian Textile Industry — Research and Application

Presented at the 13th Congress of the International Federation of Associations of Textile Chemists and Colourists in London on 21 September 1984. The Colour Measurement and Recipe Formulation Centre was opened some years ago to help dyehouses in the Hungarian textile industry. The work of the Centre and research conducted at various other institutions are discussed in this article. The main topics of research include linear approximations in colour calculations, statistical treatment of colour measurement data, the repeatability of textile dyeing, comparison of different methods for expressing the dyeing strength of dyestuffs, application of instrumental measurement in fastness evaluation, comparison of colour-difference formulae in establishing tolerances and in colour sorting, and the effect of mercerisation on the colour of dyed cotton.     

A Guide to the Measurement of Colour and Colour Differences with Photoelectric Tristimulus Colorimeters

Recommendations are made for the measurement of colour and colour differences with photoelectric tristimulus colorimeters. Instrument standardisation, measurements on one sample, measurement of colour differences and procedures of sample presentation and measurement are discussed. Finally, a recommended procedure is detailed.     

Colour in folklore and tradition—The principles

Human beings use colour to manipulate their personal appearance and environment. A large part of this usage falls within the area of oral tradition and ritual that have been handed down within families, tribes or geographical areas. The resulting images are part of our culture; they are activities that give us feelings of belonging and of doing the ‘right thing’. Two surveys were designed to learn more of these very human activities. The first centered on Britain and Ireland; the other was international. Three major driving forces were found for the use of colour in folklore and symbolism—economic, historical and social. The Principle of Adaptation of Physical Resources accounts for the choice of mourning colours of most countries. Colour usage in death echoes the three approaches to mourning of sadness, joy (for the life of the dead), and fear of the spirits of the dead. The Principle of Adaptation of Ideas accounts for regional variations in colour folklore. This embodies a Darwinian‐type principle of behavior, that is, “to survive within a community a belief must have relevance to that community.” A major principle of folk medicine involving colour is the Principle of curing like with like. There are four Principles of Colour Selection in folklore—by the contrast displayed, as a transfer from the perceived or actual usefulness of the colour, by association, and by availability. Green above all colours has especial significance both in the UK and Ireland. In everyday language it is the Principle of Singularity that controls use of colour words as symbols. The biological mechanism permitting these many and contrasting uses of colour depends on the fact that colour is a perception, not the property of an object. That is, a colour can ‘mean’ whatever we wish it to ‘mean’. © 2003 Wiley Periodicals, Inc. Col Res Appl, 29, 57–66, 2004; Published online in Wiley Interscience (www.interscience.wiley.com). DOI 10.1002/col.10212     

The Photochemical Decomposition of Aryldiazonium Salts I—Stability and Quantum Yields

The photochemical decomposition of some aryldiazonium chlorides stabilised as zinc chloride double salts and incorporated in secondary cellulose acetate film has been studied by determining concentrations of residual salts after irradiation with a xenon-arc lamp. Residual concentrations were measured by coupling the undecomposed diazonium salt to form coloured compounds, which were then estimated by visible-light microspectrophotometry. Rates of fading for these salts indicate first-order kinetics. Quantum yields are approximately 0–2, with the exception of those for p-monoalkylamino derivatives, which are appreciably higher.     

改进前处理方法测量土壤中痕量砷的重复性和重现性

为验证新的砷前处理方法,在本次实验中分别于2010年3月28El、3月31日和4月4日共进行3次重现性验证,同一样品砷含量的平行值分别为8．14×10^-6和8．60×10^-6、8．04×10^-6和8．68×10^-6以及8．20×10^-6和8．21×10^-6重复性和重现性均非常好;三次实验中样品加标回收率分别为104％、99．1％和104％,标准样品砷含量的平行值分别为11．2×10^-6和10．9×10^-6、10．8×10^-6和11．0×10^-6以及11．5×10^-6和11．0×10^-6,表明该前处理方法能完全溶解出土壤中的砷元素,重复性和重现性均优良;三次实验中的标准曲线线性重现性非常得好,斜率和截距变换不大,均在合理变化范围之内。     

Particle Measurement Programme (PMP) Light-Duty Inter-Laboratory Exercise: Repeatability and Reproducibility of the Particle Number Method

A Euro 4 Light-Duty Diesel vehicle equipped with a diesel particulate filter (DPF) was circulated to 9 labs where repetitions of the current regulatory New European Drive Cycle (NEDC) were conducted. Regulated gaseous and improved (with cyclone, filter temperature 47 ± 5°C, constant filter face velocity, high precision balance at all labs) particulate mass (PM) measurements were also conducted. A reference particle number (PN) measurement system measuring non-volatile particles was circulated along with the test vehicle. Labs also tested their own PN systems built to comply with the reference system's performance specifications. The mean PN emissions level of the vehicle was below 1 × 10¹¹ particles/km. The intra-lab variability (repeatability) was ～ 40% and the inter-lab variation was ～ 25%. The study showed that the new PN method had similar variability to other gaseous pollutants such as carbon monoxide and hydrocarbons and better than the PM (intra-lab variability ～ 55% and inter-lab ～ 35%). Even with the improved PM method the emissions of the vehicle were similar to the background level (～ 0.4 mg/km) and the method was subject to volatile artifact. The PN method showed greater sensitivity than the PM method as it could distinguish the DPF fill state or different preconditioning states of the vehicle. However, the PN emission level of the vehicle estimated by the reference system were on average 15% higher than any given lab's own system, indicating that the procedures and calibration designed for the standardization of performance should be precisely defined and followed.     

3K碳纤维拉伸性能测试方法的重复性和再现性

利用实验室循环比对试验的方法,研究了3K碳纤维拉伸性能试验方法的重复性和再现性,丰富了拉伸性能试验方法精密度数据,为准确测定和评价碳纤维拉伸强度和模量提供了科学的依据,为ISO标准和国标的制修订进一步积累了数据。     

Publication Sponsored by the Society's Colour Measurement Committee — XIV The Impact of Modern Lighting on the Dyer

Until recently, the two desirable characteristics of high lamp efficacy and good colour rendering were mutually exclusive in fluorescent lamps but in 1971 calculations were made which showed that they could co-exist if the emitted light approached a 3-line spectral power distribution (SPD), ideally the emission bands being at 450, 540 and 610 nm. The discovery of new phosphors has made such lamps a practical possibility and two manufacturers have marketed lamps whose SPDs lie between the continuous SPD of conventional lamps and the 3-line ideal. Such lamps have been found to render many objects more colourful than any conventional lamps and thus more acceptable to the average observer. This combination of desirable characteristics suggests that such lamps may become the most common form of artificial lighting, especially in view of the need to conserve fossil fuels. Tire installation of one of these lamps in a large department store, however, caused some serious problems with textiles which were metameric matches. These may be more serious with sources whose SPDs are closer to the 3-line ideal. The same problems will also occur with nontextile materials, e.g. ceramics and plastics, which match under various conventional sources. These developments in lighting may make extensive re-matching necessary.     

Constant-temperature Dyeing Process for Nylon Fibres I—A Study of the Mechanisms

The various interactions that can occur in a dyebath containing nylon, an anionic dye, an anionic agent (Lissapol D) and a mildly cationic agent (Dispersol CWL) are described and discussed. A mechanism by which these agents influence the dyeing of nylon is postulated. The importance of considering the individual behaviour of anionic dyes in such a dyeing system is emphasised, since it is demonstrated that the strengths of the complexes formed between dye and cationic agent vary from dye to dye, in some instances being more stable and in others less stable than that between the anionic and the cationic agents.