Synthetic white pigments (white titanium and white zinc) in different binding media. Influence of environmental agents
Graphical abstract
Introduction
The use of pigments in different applications within the field of Materials Engineering, and intervention in architectonic heritage, is necessary in many cases to achieve a certain exterior appearance [1], as well as to undertake actions requiring matching visual and aesthetic characteristics [2], but also to improve, for example photovoltaic light-capturing efficiency [3], the hiding power of ceramic enamels in construction [4], [5], and acrylic photoprotective coatings [6], while lowering resource consumption [7], [8], cost, and environmental impact [4], [9], [10].
Specifically, the pigments titanium oxide and zinc oxide are frequently used in different materials and media that come from natural or artificial raw materials [11], [12], [13] with a broad range of compositions and various proportions of pigments together with different media needed for their application and composition. Many factors during the production of these mixtures affect the quality and the technical features, such as the type of pigment, the binder and the composition (in the process of manufacturing and its applications).
It is fundamental to know the performance of these pigments in different media and guarantee greater suitability and durability of their effectiveness as well as their characteristics and finishes [14], [15], as these are determinant in architectonic materials and designs as well as in restoration [16]. Also of special importance is the need to ascertain the effect both the aging as well as of the exposure to environmental agents, UV rays, heating, and humidity.
Technically, many studies and manufacturers have investigated the features of the pigments, the characteristics of organic as well as inorganic pigments, which have focused primarily on the production processes and their formulation, the most suitable application methods that preserve the environment, resource savings, and product finish. However, their performance and effectiveness differ depending on the media and exposure conditions. Therefore these materials need to be studied by aging tests to quantify their technical properties.
In the present work, we focus on one of the applications mentioned, specifically the one related to the field of restoration of cultural heritage and architectonic interventions. In this sense, we examine the intended use for the pigments studied, the suitability of their physical characteristics, and the features of the materials, and we investigate their colorimetric implications.
The function of pigments is fundamental in the preparation of the chromatic palette as well as throughout the execution of artwork. Today, white pigments are used in the field of art, decoration, building, industry, serving as bases, preparation, coatings, and protections on all types of surfaces, this requiring resistance, durability, and stability. In addition to their use in white colour, these pigments are essential in mixtures to achieve specific tones, corrections, glazes, carnation, etc. Thus, these are essential components in any pictorial technique and therefore their nature and performance need to be ascertained not only to broaden knowledge or analyse diverse pictorial media, but also to control possible restoration/conservation techniques. In this respect, it is important to understand their reaction with the passage of time as well as the effect of environmental agents such as the exposure to given levels of ultraviolet radiation, rises in temperature, or variations in relative humidity, as demonstrated elsewhere [17], [18], [19], [20], [21], [22], [23], [24], [25], [26], [27]. The general behaviour of pigments has been established in some pictorial media according to the physical–chemical features of the material. Recent works have applied instrumental colour study in the field of monumental heritage, as in monitoring stone restoration [28], [29], as well as in analysing the performance of pigments treated with restoration products [30], [31], [32], [33], [34], [35], [36].
To determine the main factors that influence the characteristics of the material, we used different experimental techniques. The performance of the pigments O2Ti and OZn were characterized in various organic and inorganic binders, by X-ray diffraction (XRD), scanning electron microscopy (SEM), and inductively coupled plasma mass spectrometry (ICP-MS), in an effort to recognize the structural changes and development of new mineral phases, while chromatic performance was assessed by diffuse spectral-reflectance measurements.
The media selected included binders and solvents belonging to classical media (linseed oil, poppyseed oil and mastic varnish) as well as new synthetic products (resins, vinyl emulsions …), enabling a comparison between the old and new techniques.
On the other hand, both pigments were selected according to their stability, their widespread use, and their ease of handling. Nevertheless, except for certain characteristics, they present optimal properties to be mixed with fatty or lean binders. The two pigments resistant to solvents and to alkali, these are appropriate for use in different applications and especially in interior constructions as well as exterior constructions.
The colour-difference values (total colour ΔE, luminosity ΔL, chroma ΔC, and hue ΔH) between the mixture and the pure pigment in each of the media studied identified which of them offered greater effectiveness and stability and indicated their chromatic specifications (higher or lower degree of luminosity and chroma, and possible variation of hue); but, above all, it provided a quantitative evaluation of the influence of the environment on the medium, with respect to the final visual result.
Section snippets
Materials and methods
Two inorganic pigments were studied: titanium white (Colour Index Name PW 6 and Colour Index Number 77891) and zinc white (Colour Index Name PW 4 and Colour Index Number 77947) (Table 1).
With respect to the titanium white used in this work, the results of the XRD analysis (Fig. 1) indicated that this was a polymorphous anatase synthetic, of chemical composition O2Ti, of great purity [37]. It has an excellent lightfastness rating and permanency, with high opacity (high covering power); a tint
Results and discussion
In microstructure analysis the results proved more significant differences between the non-aged samples and the naturally aged ones (after polymerization) and the ones aged by infrared warming and saturated humidity (Fig. 2, Fig. 3).
Visually, a pronounced textural change occurred in the samples aged naturally in comparison to the non-aged ones, with a greater increase in the samples subjected to infrared aging and saturated humidity. These textural changes developed generally from more smoothed
Conclusions
The use of mass spectrometry has enabled the rapid and reliable detection of the transformation of the organic compounds used as binders of the different samples prepared after the aging tests, indicating a consistent time course for these compounds.
The use of scanning electron microscopy revealed the textural changes in relation to the variations in luminosity and darkening of the samples, which in terms of visual colour translates as a trend towards grey or black.
Instrumental techniques have
Acknowledgements
The research presented in this paper is part of Project MAT 2002-03227 of the National Plan for Scientific Research, Development and Technological Innovation (Ministry of Science and Technology) and was carried out under the auspices of Research Groups RNM 0179 and HUM 629 of the Junta de Andalucía and REMINE Programme for Research and Innovation Horizon 2020 Marie Skłodowska-Curie Actions.
References (50)
- et al.
Behaviour of nanoparticle (ultrafine) titanium dioxide pigments and stabilisers on the photooxidative stability of water based acrylic and isocyanate based acrylic coatings
Polym. Degrad. Stab.
(2002) - et al.
TiO2 pigment technology: a review
Prog. Org. Coat.
(1992) - et al.
Separation of data on the training and test set for modelling: a case study for modelling of five colour properties of a white pigment
Chemom. Intell. Lab. Syst.
(2003) Surface dynamics of defect formation in paint films
Prog. Org. Coat.
(1975)- et al.
Colorimetric cataloguing of stone materials (biocalcarenite) and evaluation of the chromatic effects of different restoring agents
Sci. Total Environ.
(1995) - et al.
Rough and polished travertine building stone decay evaluated by a marine aerosol ageing test
Constr. Build. Mater.
(2010) - et al.
Estudio colorimétrico de los azulejos del Patio de las Doncellas del Real Alcázar de Sevilla (España)
Bol. Soc. Esp. Ceram. Vidrio
(2015) - et al.
Optical properties of anatase (TiO2)
Solid State Commun.
(1994) Observation and measurement of the appearance of metallic materials. Part I. Macro appearance
Color Res. Appl.
(1996)- et al.
Observation of visual texture of metallic and pearlescent materials
Color Res. Appl.
(2007)
Efecto de la incorporación de nanopartículas de grafeno en dispositivos fotovoltaicos de óxido de titanio sensibilizadas por colorante orgánico
NanoGe J. Energy Sustainability
Evaluation of zinc oxide catalysts and their catalytic activity in the reaction for the production of transesterification biodiesel
Afinidad
Desarrollo de un software de gestión de color para la industria cerámica
Bol. Soc. Esp. Ceram. Vidrio
Películas nano estructuradas de oxido de zin c(ZnO)
Sci. Tech.
Estudio DFT de propiedades estructurales y electrónicas del óxido de titanio en sus fases: rutilo, anatasa y brookita
Rev. Colomb Mater.
Structure and properties of Portland cement clinker doped with zinc oxide
J. Am. Ceram. Soc.
Degradación fotocatalítica de fluoresceína sódica con óxido de titanio
CIENCIA Ergo-Sum
Exposure studies of exterior house paints containing kaolin clay pigments
J. Coatings Technol.
Billmeyer and Saltzman’s Principles of Color Technology
Laser diagnostics of painted artworks: laser-induced breakdown spectroscopy in pigment identification
Appl. Spectrosc.
Colorimetric and microscopic study of the thermal behavior of new ceramic pigments
Microsc. Res. Tech.
Enhanced Performance and Functionality of Titanium Dioxide Papermaking Pigments with Controlled Morphology and Surface Coating
Estudio comparativo de ligantes clásicos en dispersión a base de copolímeros acrílicos y acrílicos estirénicos para pinturas de fachadas
Los materiales de pintura y su empleo en el arte
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- 1
Address: Departamento de Mineralogía y Petrología, Facultad de Ciencias, Universidad de Granada, c/ Severo Ochoa s/n, 18071 Granada, Spain.
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Address: Departamento de Pintura y Escultura, Facultad de Bellas Artes, Universidad de Granada, Avda. Andalucía s/n. Edif., Aynadamar, 18071 Granada, Spain.