The Chemical Nature of Chalking in the Presence of Titanium Dioxide Pigments

G, Voelz H; Kaempf, G; Fitzky, H. G.; Klaeren, A

doi:10.1021/bk-1981-0151.ch012

Cited by 58 publications

(18 citation statements)

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“…The reaction takes place mainly via photoactivated states of the binder macromolecules. Excited states of the O 2 molecules play a minor role [8]. In the photocalytic oxidation cycle, on the other hand, the pigment plays a part as a catalyst.…”

Section: Resultsmentioning

confidence: 99%

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A study on usability of magnesium oxide with titanium dioxide in PVC door and window profiles

Kamışlı

Turan

2005

Journal of Materials Processing Technology

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Section: Resultsmentioning

confidence: 99%

“…In the photocalytic oxidation cycle, on the other hand, the pigment plays a part as a catalyst. The process of photocatalytic oxidation caused by TiO 2 pigments [8].…”

Section: Resultsmentioning

confidence: 99%

A study on usability of magnesium oxide with titanium dioxide in PVC door and window profiles

Kamışlı

Turan

2005

Journal of Materials Processing Technology

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“…Photocatalytic degradation occurs when UV excitation of an electron leads to radical formation at the pigment surface. These radicals can attack their surroundings and thus cause degradation [4,8]. In the case of oil paint, the binder is broken down into volatile components until the pigment is left unbound at the paint surface (chalking).…”

Section: Introductionmentioning

confidence: 99%

Investigating the effect of artists’ paint formulation on degradation rates of TiO2-based oil paints

et al. 2018

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This study reports on the effect of artists' paint formulation on degradation rates of TiO 2 -based oil paints. Titanium white oil paint exists in a multitude of different recipes, and the effect of the formulation on photocatalytic binder degradation kinetics is unknown. These formulations contain, among others, one or both titanium dioxide polymorphs, zinc oxide, the extenders barium sulfate or calcium carbonate and various additives. Most research performed on the photocatalytic degradation process focusses on pure titanium white-binder mixtures and thus does not take into account the complete paint system. Since photocatalytic oil degradation is a process initiated by the absorption of UV light, any ingredient or combination of ingredients influencing the light scattering and absorption properties of the paint films may affect the degradation rate. In this study three sets of experiments are conducted, designed using the design of experiments (DoE) approach, to screen for the most important formulation factors influencing the degradation rate. The benefits of using DoE, compared to a more traditional 'one factor at a time approach' are robustness, sample efficiency, the ability of evaluate mixtures of multiple components as well as the ability to evaluate factor interactions. The three sets of experiments investigate (1) the influence of the TiO 2 type, (2) the impact of different mixtures of two types of TiO 2 , ZnO and the additive aluminum stearate and (3) the influence of common extenders in combination with photocatalytic TiO 2 , on the photocatalytic degradation of the oil binder. The impact of the formulation on the degradation rate became apparent, indicating the shortcoming of oversimplified studies. The protective effect of photostable TiO 2 pigments, even in a mixture with photocatalytic TiO 2 pigments, as well as the negative effect of extenders was demonstrated. Furthermore, the ambiguous role of ZnO (photocatalytic or not) and aluminum stearate is highlighted. Neither can be ignored in a study of degradation behavior of modern oil paints and require further investigation.

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“…The driving force was the need to know the extent of use of titanium white in relation to its risk of photocatalytic degradation [16][17][18]. The timing of titanium white becoming popular amongst artists is important, as it possibly relates to the quality of those pigments.…”

Section: Introductionmentioning

confidence: 99%

The white of the 20th century: an explorative survey into Dutch modern art collections

et al. 2018

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White pigments were abundantly used in 20th century paintings, and relate to several degradation risks such as titanium white mediated photocatalytic binder degradation or zinc soap formation. Knowledge about the white pigments that were used is essential for risk assessments of 20th century collections. In this study, a representative set of 179 paintings in Dutch modern art collections were analyzed by portable X-ray fluorescence spectrometry. Subsequent explorative data analysis was performed, supported by qualitative findings from 140 home-made reference samples. Micro-samples were further investigated by X-ray diffraction and scanning transmission electron microscopy to gain information about crystal structure and surface coating. This study reveals that Dutch 20th century artists were hesitant to use titanium white. In the Netherlands, the use of this pigment is observed convincingly from the 1970s onward and initially mostly in non-oil binders. Additionally, lead white was used until late in the 20th century for paints and grounds but rarely mixed with titanium white in paints. The study also indicated that many CoBrA artists used zinc white, underlining the risk of degradation due to soap formation. Furthermore, this study highlights the different production processes of titanium white. Through the association of titanium with niobium, an impurity only present for sulfate processed pigments, the production process can be identified. The absence of niobium indicates the presence of rutile and is thus a sign of paint stability, as well as a 'post 1959' dating. This explorative study illustrates the value of a combination of data analysis approaches, which includes assessment of spectra as well as descriptive, bivariate and multivariate analysis, for medium-sized datasets gathered at similar conditions.

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The Chemical Nature of Chalking in the Presence of Titanium Dioxide Pigments

Cited by 58 publications

References 0 publications

A study on usability of magnesium oxide with titanium dioxide in PVC door and window profiles

A study on usability of magnesium oxide with titanium dioxide in PVC door and window profiles

Investigating the effect of artists’ paint formulation on degradation rates of TiO2-based oil paints

The white of the 20th century: an explorative survey into Dutch modern art collections

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