The present study investigates the relationships of gloss levels to color measurements at different observation angles for solid color samples, based on measurements made using a multi-angle gonio-spectrophotometer. We analyzed seven distinct hues (green, yellow, red, blue, gray, black, and white) to ensure comprehensive coverage of color variations. Although goniochromatic effects are generally attributed to effect pigments, our research indicates that typical solid colors also exhibit considerable color variation with angle, especially at reduced gloss levels. We prepared 42 samples that varied in gloss levels, which displayed a strong inverse correlation between gloss and consistency of color with angles, and for low-gloss samples, we found those samples varied the most with viewing angle. In addition, darker and more saturated colors (such as black and red) showed greater variability than lighter colors (such as white and yellow), and we identified an important gloss threshold of around 40 gloss units, where below this level, color stability declines sharply. Comparative analysis across multiple reference angles (20°, 45°, 75°, and 110°) confirmed the robustness of these findings. These outcomes challenge the typical method of observing color based on a single angle and demonstrate the necessity of applying a multi-angle measurement to low-gloss solid colors. They also have implications for industries which maintain longstanding color quality requirements in terms of improving color quality specifications and measurement for the long-term.

This paper presents an experimental investigation into the estimation of specular gloss from the colorimetric data. The 28 samples were selected from the Natural Color System (NCS) gloss scale, which had different combinations of lightness and gloss levels. The samples' spectral reflectance and colorimetric data Y and L* were measured by a d:8 degrees geometry reflectance spectrophotometer in both SCE (Specular Component Excluded) and SCI (Specular Component Included) modes. Additionally, the specular gloss of the samples at three common angles 20(degrees), 60(degrees), and 85(degrees) was measured using a gloss meter. The correlation and relationship between DYSCI-SCE and DL*(SCI-SCE) and the specular gloss values measured for the samples at different angles were evaluated and analyzed with linear and second-polynomial regression functions. The results were validated with a different set of data acquired from 32 random solid-coated samples. The results showed the best fitting was achieved at 60(degrees) of gloss measurement with a second-polynomial function. As the specular gloss of DY decreased, like in a matt sample, the estimation error of specular gloss increased with a large error of over 10%.

It is essential to investigate calibrated BCRA ceramic standards reference' color stability to determine the reflectance spectrophotometer's calibration period time. In this research, the color and spectral changes of a set of fourteen BCRA ceramic standards made by Avian Technologies Company were investigated over three years under repeatable conditions. Each ceramic's color changes were evaluated by calculating ∆E*ab and ∆E*00 and then analyzed using univariate statistic metrics such as MCDM and RMS (2S). Similarly, the spectral reflectance factor's variation was evaluated using univariate metrics of the standard deviation of reflectance (∆Rλ,2δ) and RMSR. This study's statistical results showed that the color and spectral reflectance factor of BCRA ceramic standards had no significant changes for three years and established good color stability. The maximum values were obtained for the statistic metric of MCDM (ΔE*ab) within about 0.08 units and the statistic metric of RMSR within about 0.02%. This result can play a significant role in reducing the recalibration costs of these reference ceramics.

Measuring gloss, visually or instrumentally, has been a challenge in many manufacturing and service industries. However, there exists no standardized method for visual evaluation of equidistance specular gloss. This study aimed to design and prepare a psychometric visually equispaced specular gloss scale for the visual measurement of gloss or any other geometric appearance attribute. To this end, a series of lithographically printed black papers, with different levels of gloss from low to high, were prepared to constitute a visually uniform specular gloss scale. Fourteen observers visually quantified the scale in a unidirectional illumination at three different geometries. Analyzing the results shows that the 60° geometry can quantify the equivalent specular gloss efficiently. A uniform specular gloss scale was prepared by assessing the prepared scale visually under the unidirectional illumination at the 60° geometry. Such a visually uniform specular gloss scale could be employed to develop a standard visual evaluation method of specular gloss in all related industries.

K/S and reflectance graphs are essential tools in characterizing the dyeing behavior. In textile coloration, estimating the dye concentration is poor using the Kubelka-Munk model due to its low scalability and deviation of the reflectance function from linearity after low dye concentrations, particularly in the wavelengths where the gradient of K/S against dye concentration is noticeable. This paper focused on extending the validity of the Kubelka-Munk function, which originates from the linearity of reflectance function against higher dye concentration. A data set of dyed polyester specimens with three disperse dyes in a dye concentration range was prepared. At the present work, K/S was analyzed by describing the scalability property, and the suitable wavelengths in the visible spectrum where K/S benefits from minor deviation from linearity were also discussed. It was observed that the K/S function is not always scalable and deviates in λ max after a specific dye concentration for K/S > 17. Accordingly, the wavelengths other than λ max were found that could be as important as λ max. For the K/S values > 25, no practical region was achieved.

The aim of the present study was to investigate the effect of color attributes of appearance on the corresponding geometric attributes of appearance of non-effect coatings. Three scales, namely gloss, distinctness of image, and orange peel for three achromatic (black, gray, and white) and four chromatic (red, green, blue, and yellow) basecoats, each at varying levels, were prepared. The gloss and the distinctness of image scales had a sample with a maximum degree of gloss and distinctness of image, respectively, and the orange peel scale had a sample with a minimum degree of orange peel, which was considered to be the standard sample. The visual differences between the standard sample and those remaining in each scale were assessed by a panel of 28 observers using a prepared one-dimensional lightness scale based on the CIELAB and CIEDE2000 color difference equations. The correlations between visual and instrumental measurements of scales were checked, and instrumental performance with respect to visually assessed equivalent differences in gloss, distinctness of image, and orange peel were determined, giving STRESS (standardized residual sum of squares) values = 24.3, 11.6, and 9.7, respectively, in terms of CIELAB. ANOVA together with simple, lasso, and ridge regressions were applied to test the effect of color on the geometric attributes of appearance. The results illustrate that color attributes of appearance have no adverse significant effect on the main geometric attributes of appearance for non-effect coatings.

Objective: Bulk-fill composites are a group of composite resins designed for easy and fast filling of large cavities. This study aimed to assess the color stability of bulk-fill composites subjected to xenon radiation and evaluate their color change (ΔE) following polymerization.Methods: In this in vitro experimental study, 30 specimens (4mm in height and 8mm in diameter) were fabricated of x-traFil and Tetric N-Ceram universal color bulk-fill composites and A2 shade of Grandio composite (as control). Bulk-fill composites were placed in the mold in 4mm thickness according to the manufacturers’ instructions. In the control group, composite was applied to the mold in two layers each with 2mm thickness. Tetric and Grandio composites were cured for 20 seconds and x-traFil was cured for 10 seconds with a LED light-curing unit. A total of 15 specimens (five of each composite) were used for each test. For assessment of color change due to polymerization, L*, a* and b* color parameters were measured before and immediately after polymerization and also 30 days after immersion in distilled water in an incubator at 37°C and 70% humidity using a spectroradiometer. For xenon test, the specimens were subjected to color analysis after 48 hours of storage in distilled water. Next, they were subjected to xenon lamp radiation in xenon environment chamber for 122 hours at 22°C and 25% humidity and then the color parameters were measured again. The mean and standard deviation (SD) of all values were calculated. One-way and repeated measures ANOVA were used to compare ΔE and ΔL among the groups. Tukey’s HSD test was used for pairwise comparisons.Results: The value of ΔE immediately after polymerization was the lowest for Grandio (4.91) and the highest for Tetric (9.44). Thirty days after the polymerization, ΔE was the lowest in Grandio (3.07) and the highest in Tetric (9.27); ΔE showed a decreasing trend over time in all specimens. Under xenon light radiation, Grandio showed the lowest (1.50) and Tetric showed the highest ΔE (11.15).Conclusion: Following polymerization and under xenon lamp radiation, ΔE of conventional composite was less than that of bulk-fill composites.

The aim of this study was to quantify orange-peel texture with an instrumentally based single-number index highly correlated with equivalent visual assessments. We prepared 3 achromatic (black, grey, and white) and 4 chromatic (red, green, blue, and yellow) scales, each with 8 different levels of orange-peel texture. Each scale had a sample with a minimum degree of orange peel, which was considered to be the standard sample. The visual differences between the standard sample and the remaining ones with progressively increasing degrees of orange peel in each scale were assessed by a panel of 28 observers using a prepared one dimensional lightness scale based on CIELAB. The usual parameters for surface texture provided by the BYK instrument were measured for each of the 56 paint samples and used to develop different models under the assumption of the additivity principle. The coefficients of these models and their performance with respect to visually assessed equivalent differences in orange peel were determined. Ridge regression was used to address multicollinearity between parameters. The validity of the models derived as well as other indices were further tested using the ACT (Advanced Coating Technologies) standard panels. ANOVA analyses indicate that chromatic samples have no adverse significant effects on the orange peel. Predictions of visual orange peel texture results by one of our models are considerably good [R-2 = 0.98; STRESS (Standardized Residual Sum of Squares) = 6.3] and therefore, this index is recommended as an index of orange peel.

Attempts were made to evaluate mathematically and empirically the accuracy of the Kubelka–Munk model for color match prediction of opaque and translucent surface coatings in the color using industries. To this end, an innovative inversed mathematical evaluation procedure was concocted which comprised of plotting the absorption and scattering constants of the Kubelka–Munk model or any of its various modified form or replacements theories against the intrinsic optical coefficients of the respective exact radiation transfer theories, namely Chandrasekhar for opaque and van de Hulst for translucent media. The results prove mathematically that the Kubelka–Munk model for opaque media is a sound theory and its various suggested modifications or replacements do not improve the color match prediction of opaque surface coating media. This mathematical conclusion was further confirmed by color match prediction of actual opaque paint samples. On the other hand, the mathematical prediction for translucent media illustrated a completely different picture, depicting nonlinearity between the optical constants and the respective concentrations of colorants. This implies that much further work has to be carried out to derive invertible new equations to enforce linearity to such situations or make use of alternative artificial intelligent procedures which are designed especially for nonlinearity.

In the present investigation four spectrophotometers from different models of the X-Rite company were compared in terms of precision and truness using BCRA standard tiles. We investigated the effect of manufacturer’s re-calibration procedure on the reduction of error for spectrophotometers in which only two of them were calibrated. The repeatability results of this research show that the precision of all spectrophotometers is acceptable and there is no significant difference between calibrated and non-calibrated devices. Moreover, the average of color difference results for a series of fourteen BCRA tiles show that only the CE7000 A as a non-calibrated spectrophotometer needs the manufacturer’s re-calibration procedure whereas the SP62 spectrophotometer which was not calibrated, shows no significant error in comparison to both other calibrated devices. Additionally for achromatic tiles, the new calibrated Ci64 device demonstrates a larger error than both SP62 and SP64 devices. Meanwhile, the average of color difference values per device for BCRA tiles are larger than acceptable values. Therefore, it seems that the acceptable value for trueness of spectrophotometers is an unreasonable expectation and needs to be revised.

In this paper, the perceived blackness of 10 specific automotive finishes with different levels of orange peel attribute is investigated under the diffuse illumination condition. Since the purchased ACT black panels had approximately the same colorimetric attributes, i.e., lightness, hue, and chroma, the effect of colorimetric properties on perceived blackness was minimized. Thirty nonexpert observers including 14 males and 16 females were selected to compare the blackness perception of ACT black panels. The observers’ normal color vision was already evaluated by applying the Ishihara test method. The black panels were ranked from the minimum perceived blackness to the maximum by employing the pair comparison method and performing 1800 visual assessments. Results showed that, in general, the blackness perception of panels increased with a decrease in their orange peel attributes, but the orange peel attribute is not the only factor affecting the perceived blackness of black panels. Besides, while the black panels were colorimetrically too close to each other, the panel with the lowest lightness and chroma value was assessed as the blackest sample among the ACT panels with the lowest orange peel attribute.

In the present study, attempts were made to clarify the existence of a correlation between visually perceived and instrumentally measured specular gloss of a series of achromatic samples. To this end, seven achromatic physical scales of specular gloss each consisting of 10 or 11 samples were prepared using lithographically printed black, white, and five in between gray papers. The samples were visually assessed and subsequently quantified in terms of a visually uniform color constant lightness scale, by a panel of 14 observers in an especially designed unidirectional light compartment at three illumination/observation geometries, namely 20°/20°, 60°/60°, and 85°/85°. Four statistical parameters were utilized to determine the correlation between visually perceived and instrumentally measured specular gloss. The results show that the instrumental 60°/60° geometry is capable of efficiently quantifying the equivalent specular gloss as perceived by a human observer. Surprisingly, it was also possible to accurately predict the visually quantified specular gloss both at the 20° and the 85° geometries by the aid of applying special linear relationships derived from the instrumentally measured specular gloss of the 60° geometry.

The blackness perception of six black automotive finishes was evaluated under three different illumination conditions: unidirectional illumination, diffuse illumination and light booth condition. The metallic black panels with approximately the same appearance attributes, specular gloss, distinctness of image and orange peel, were selected to minimize the effect of total appearance factors on perceived blackness. Fourteen non-expert observers (5 males and 9 females) assessed the black panels while their normal color vision was examined by the Ishihara test. The pair comparison method was applied to rank the metallic black panels based on their perceived blackness. The results showed that under the diffuse illumination condition, a good correlation was observed between the lightness attribute of metallic black panels and their visual scales, where a decrease of the L* value leads to an increase of perceived blackness. In addition, observers assessed the darkest and the most neutral panel as the blackest sample under the three applied illumination conditions.

AIM The aim of the present study was to evaluate the effect of two fluoride varnishes on color stability of three resin-based restorative materials. METHODS Fifty-four discs (14.5 × 1.7 mm) were fabricated from A2 and A3 shades of a compomer (F2000), a flowable composite (Z350), and a hybrid composite (Z250), and incubated at 37°C for 48 h. Dura Shield (colored) and Fluor Protector (colorless) fluoride varnishes were applied onto the discs. The coating was cleaned using a low-speed handpiece and nylon bristle brush after 24 h of storage in distilled water. A second coating was then applied. A control group with no coating was immersed in distilled water and used. The CIE L*a*b* color scale was measured before the treatments and following each cleaning utilizing a spectrophotometer. RESULTS The colored fluoride varnish exhibited the highest overall color change (∆E) after the first and the second cleaning procedures in all the materials. Among these, the greatest color change was observed in the A3 shade of F2000, followed by the A3 shade of Z-250. The ∆E was less than 3.3 in all groups, and was therefore clinically acceptable. CONCLUSION Color changes following the application of fluoride varnishes were found to be clinically acceptable in all groups.

يرماع داهرف 1 * يليلخ همجن، 2 يليلجريم هتشرف ، 3 1 ـ هوژپ هسسوم،گنر كيزيف يشهوژپ هورگ ،رايداتسا يتسپ قودنص ،ناريا ،نارهت ،ششوپ و گنر يروانف و مولع يش : 654 16765 2 ـ يتسپ قودنص ،ناريا ،نارهت ،ششوپ و گنر يروانف و مولع يشهوژپ هسسوم ،گنر كيزيف يشهوژپ هورگ،يشهوژپ سانشراك : 654 16765 3 ـ نارهت ،ريبكريما يتعنص هاگشناد ،گنر و رميلپ يسدنهم هدكشناد ،يرتكد يوجشناد يتسپ قودنص ،ناريا : 4413 15875 تفايرد خيرات : 21 / 9 / 92 شريذپ خيرات : 24 / 2 / 93 زا يكينورتكلا تروص هب سرتسد رد : 20 / 6 / 1393

In the present investigation, the effectiveness of "Structure Balance Index" in correctly predicting the appearance of visually assessed achromatic automotive finishes was evaluated. For visual evaluation, the pair comparison method utilizing 16 observers assessing in a light cabinet, having a 45/0 viewing geometry, was used. The statistical results show that the observer repeatability and reproducibility were acceptable. However, evaluation of the Balance index (B) illustrates that the tolerance regions of green, yellow and red in the Balance chart of the presently prepared achromatic samples differed from the BYK's originally defined regions when compared to visual assessments. This means that this index cannot be extended to all lightness levels. Furthermore, such acceptability regions of green, yellow and red are not symmetrical enough for different lightness to promote the balance index for general use. Instead, this index can be regarded as a secondary fine-tuning corrector of Wd and LW parameters. (C) 2013 Elsevier B.V. All rights reserved.

Appearance control has continuously been a major challenge to the automotive industry. In order to implement a consistent control on the appearance of automotive finishes, objective measurement of various appearance attributes such as gloss, distinctness of image, orange peel, etc., is indispensable to the automotive manufacturers. In the present study, attempts were made to find the correlation between visually perceived and instrumentally measured appearance of achromatic automotive finishes. To this end, three physical scales of appearance attributes, namely specular gloss, distinctness of image, and orange peel were prepared using a series of metallic black, metallic gray, metallic silver, and solid white automotive finishes. The samples were visually evaluated by a panel of 16 observers, by utilizing an also prepared lightness scale, in a light cabinet having a 45/0 illumination/observation geometry. The innovative use of a common lightness scale in the present study showed that there is a surprisingly good correlation between instrumentally measured specular gloss, distinctness of image, and Wave scan LW and Wd parameters, and the corresponding visually evaluated data at the four investigated achromatic levels.

In the present study, attempts were made to develop an index of geometric appearance capable of accurately predicting and quantifying the visually perceived geometric aspects of appearance of achromatic automotive finishes. To this end, three previously prepared individual scales for the three most significant geometric appearance attributes, namely specular gloss, distinctness of image (DOI), and orange peel for each of a series of metallic black, metallic gray, metallic silver, and solid white automotive finishes were utilized. The differences in each attribute were quantified visually by a panel of 16 observers, in terms of a lightness difference of an also previously prepared lightness scale. The innovative use of a common lightness scale showed that there is a surprisingly good correlation between the instrumentally measured specular gloss, DOI, and the LW parameter of the Wave scan instrument and the corresponding visually evaluated equivalents at the four investigated achromatic levels through minimizing observer errors and enhancing accuracy of the perceptibility procedure. These high accuracies made provisions for the implementation of the principle of additivity which led to the derivation of a geometric appearance index (GAI). However, before its derivation, one instrumentally measured parameter was remodeled exponentially to define an innovative parameter chosen to be named “percent absence of orange peel.” The proposed GAI illustrates high correlation with visual assessments and is herewith recommended as a stand-alone index for predicting the geometric appearance of automotive finishes. Furthermore, this index together with a chromatic appearance index could form the foundation for deriving a total appearance index for the automotive industry.