JOURNAL OF COLOR SCIENCE AND TECHNOLOGY
Year:2018 | Volume:12 | Issue:1 |Papers Count:7

The materials that are now being used in the conservation of historic and cultural heritage are originally available in the market of industry. Recently, some of the materials are improved in the fields of conservation of heritage and they are so common in the consolidation of artificial objects or monuments. The aim of the study is identification of the proper material for consolidation of beige stone against environmental factors. Thus, three materials were chosen from the recent products which are more compatible with composition of limestone. Stone specimens were consolidated with Nano Estel (Nanostructure silicon dioxide SiO2 dispersion in water), Nano Lime (Ca(OH)2) (Nano-lime dispersion in isopropyl alcohol), and Dibasic ammonium phosphate ((NH4)2HPO4) well known as HAP method. Samples were characterized by FE-SEM and tested by Microdrilling resistance. The porosity also was analyzed by MIP. The results show Nano-lime has the lowest surface effectiveness which barely changed the physical properties of the stone in comparison with the others. In the case of covering, in both Estel and HAP, some microcracks (with branch and net pattern) were observed on the layer above substrate, in contrast, nano-lime made a homogeneous layer. Also, nano-lime treatment caused 6% reduction of the porosity which had the most effectiveness on stone porosity. J. Color Sci. Tech. 12(2018), 1-12© . Institute for Color Science and Technology.

Water absorption measurement is one of the factors for evaluation of constructional ceramics. The tile components are glaze, engobe and biscuit. The engobe makes a flat surface on ceramic which improves glaze quality and beauty. Water absorption decreases beauty of ceramic and it may separate glaze from the biscuit. The amount of porosity in the structure of the engobe and biscuit affect water absorption. Holes and capillaries increase probability of water movement from the biscuit to the ceramic tile’ s surface. Thus changing the engobe components is a way for controlling water movement to the surface. In recent study, the effects of addition of two kinds of refractory materials such as magnesite (MgCO3) and dolomite (CaMg(CO3)2) on water absorption property of ceramic were studied. After sample preparation, engobe and glaze were coated on the biscuit and the ceramic was heated in the furnace at 1134˚ C for 42 minutes. Samples were evaluated by X-ray diffraction (XRD), scanning electron microscope (SEM), flexural strength, shrinkage and water absorption methods. The colorimetric measurements for ceramic tile surface were carried out using CIE-L*a*b* standard. The results show that after addition of magnesite and dolomite to the engobe, water absorption decreased. Also, a high shrinkage is carried out for the samples and the flexural strength increases while the brightness (L*) decreases. The SEM micrographs show that after addition of these materials, the particles in the engobe layer are sintered and block the capillaries. Thus they can prevent water diffusion to the glaze surface. . J. Color Sci. Tech. 12(2018), 13-21© . Institute for Color Science and Technology.

Electrodeposition of nano titania from aqueous dispersion has been studied. Properties of The electrodeposited layer are related to nanoparticle type, morphology, structure and process characteristics. These properties are directly affected by preparation method and electrodeposition parameters such as current density, substrate type, pH, ionic concentration, size, type of nanoparticles, electrolyte mixing, etc. Characteristics of nano titania could affect the conversion efficiency of DSSC (Dye Sensitized Solar Cell) significantly. Electrodeposition is a good candidate for applying nano titania as a semi-conductor. In this study the effect of electrodeposition current density on the adsorption of different types of dyes on electrodeposited nano titania in a DSSC has been studied. N455-PF6 showed more dye adsorption on the electrodeposited nano titania. The increasing current density, the raising nano titania thickness and deposition yield. Comparing three types of dyes (P1, N455-PF6, N719) showed that N455-PF6 represented a linear and reproducible absorption by increasing current density. J. Color Sci. Tech. 12(2018), 23-32© . Institute for Color Science and Technology.

The aim of this research is to study sandarac ingredients as a resin in Iranian market according to its molecular structure. Fourier transform infrared spectra of resins, which is sold as sandarac in Iranian market, were investigated and their spectra were compared with three reference resins including Manilla copal, Sandarac and Colophony. Sandarac is a diterpenoid resin extracted from Tetraclinis articulata Vahl as a native plant of north western Africa. It has been used for production of various kinds of painting varnishes and artwork coatings. It seems that different resins such as copal, colophony and sandarac were known as sandarac in the past. Nowadays, many resins with different forms and colors are sold in Iran as sandarac and contemporary traditional artists use them for manufacturing "Kaman Oil" coating (a traditional Persian resin– oil varnish). Results showed that all the three kinds of resins (copal, colophony and sandarac) are sold and presented in Iran as sandarac. J. Color Sci. Tech. 12(2018), 33-43© . Institute for Color Science and Technology.

Pyran derivatives have attracted many chemists due to their various biological activities and pharmacological properties such as antiviral, antibacterial and anti-inflammatory activities. In recent years, various studies have been devoted to the synthesis of novel derivatives of these compounds and several protocols have been devised for their preparation. In this research, Density Functional Theory (DFT) calculations at the B3LYP level are used to optimize the geometry of azo-linked 4H-pyran dyes. In the continuation of our study, we were interested in evaluation of homoaromaticity of the selected compounds using Nucleus Independent Chemical Shift (NICS). The studies released that, the presence of various azo substitute in atom 2 or 3 of pyran ring, make little change in NICS values and the numbers of groups or the reach of groups to atom 4 of pyran ring, and decrease the NICS value. Also, the NICS values caused by compounds containing aryl azo bridge are more suitable than other bridges. The data related HOMO-LUMO gap, also, relatively, emphasized the data caused by NICS. . J. Color Sci. Tech. 12(2018), 45-56© . Institute for Color Science and Technology.

Natural polysaccharides are environmentally friendly materials for removing toxic pollutants from aqueous solutions, and attracted much attention. Among numerous polysaccharides, starch is an abundant, inexpensive, renewable and fully biodegradable natural raw material. However, its application in dyes removal is limited due to its low capacity and stability. To circumvent these problems, modified starches has been synthesized and applied as adsorbent for anionic dyes. We showed that the Fe3O4 magnetic nanoparticles coated with dithiocarbamate-modified starch (DTCS-MNPs) is an efficient adsorbent for the removal of water-soluble anionic dyes from wastewaters. It is found that the capacity of DTCS-MNPs for each dye is pH dependent, and the adsorption is governed by electrostatic attractions. The desorption data shows that the removal percent of dye from the dye loaded DTCS-MNP is over 80% in 0, 25 mol/l Na2SO4 solutions at 25 º C. J. Color Sci. Tech. 12(2018), 57-72© . Institute for Color Science and Technology.

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. . J. Color Sci. Tech. 12(2018), 73-80© . Institute for Color Science and Technology.