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The Effects of Temperature and Relative Humidity on the Mechanical Properties of Modern Painting Materials

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Abstract

The mechanical properties of strength, modulus, and elongation to break were studied for artists' acrylic and alkyd paints under varying conditions of temperature and relative humidity (RH). In the ambient environment, 23° C, 50% RH, acrylic paints are very flexible and are able to sustain large deformations (>50%). Alkyd paints are much stiffer and stronger, and they cannot sustain deformations nearly as dramatic as the acrylics. Acrylic paints at 5% RH are stiffer and stronger than at 50% RH and their ability to stretch is lessened. At temperatures below 15° C at 50% RH, the strength and stiffness of acrylic paints begin to rise rapidly. Some were found to be brittle at 5° C, and by −3° C, all were brittle. At a lower RH, some acrylic paints became brittle at a temperature near 11° C. These temperatures and relative humidities may be found in the transport environment of art objects, and may render them subject to possible damage.

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... Inorganic pigments also tend to be much stiffer than the binding media, also leading to a significant increase in the stiffness of the sample. Many of the studies focused on the effects of temperature [18,29,30,36,37,41,43,46,50,54,57] and relative humidity [15,29,30,34,36,37,41,43,44,46,52,57,59] on the stiffness of the sample. There is a general trend across all three binding media classes of increasing stiffness as the temperature of a paint decreases, shown in Fig. 6, which would indicate that the increase in stiffness is controlled more by the properties of the binding medium than the particular pigment used. ...
... Inorganic pigments also tend to be much stiffer than the binding media, also leading to a significant increase in the stiffness of the sample. Many of the studies focused on the effects of temperature [18,29,30,36,37,41,43,46,50,54,57] and relative humidity [15,29,30,34,36,37,41,43,44,46,52,57,59] on the stiffness of the sample. There is a general trend across all three binding media classes of increasing stiffness as the temperature of a paint decreases, shown in Fig. 6, which would indicate that the increase in stiffness is controlled more by the properties of the binding medium than the particular pigment used. ...
... For all these general classes of binding media, −10 • C is below their T g , which leads to a glassier, more brittle response from the samples. When the RH is increased for a paint system, researchers observed a general softening phenomenon occur since water can act as a plasticizer in most paint films, leading to a decrease in the stiffness that can range from 30-90%. 2 [15,29,30,34,36,37,41,43,44,46,52,57,59]. When the RH is decreased, the paints become stiffer as less ambient water is present, showing anywhere from 40-300% increase in the stiffness. ...
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Typescript. Thesis (M.S.)--University of Wisconsin--Madison, 2000. Includes bibliographical references (leaves 151-155).
An Introduction Into the Mechanical Behavior of Paintings Under Rapid Loading Conditions
  • M F Mecklenburg
  • C S Tumosa
Mechanical Behavior of Paintings Subjected to Changes in Temperature and RelativeHumidity
  • M F Mecklenburg
  • C S Tumosa