Mechanical properties in canvas conservation Understanding the mechanical properties of art canvases is necessary for art conservation, especially when deciding on transporting paintings, conservation treatments and environmental specifications inside museums. Canvases are layered structures made from weaving fibers together, where each layer responds differently to changes in humidity, resulting in localized stresses that cause deformation, cracking, and delamination. There are two directions to the canvas: the warp direction (threads run vertically) and the weft direction (threads run horizontally). Researchers performed tensile testing to determine the effects of humidity on the strength of canvases and observed that increasing humidity decreased the effective elastic modulus (combined modulus of the weft and warp directions). For example, the effective modulus at 30% relative humidity is 180 MPa, which drops to 13 MPa at 90% relative humidity, suggesting that canvas is becoming more flexible and susceptible to deformation. There is an inherent anisotropy to the elastic modulus measured in the weft and warp direction as evidenced in the strain vs. load behavior of the canvas. The canvas exhibits a 0.1 strain in the weft direction and 0.2 strain in the warp direction before failing (thread ripping apart). Though, tensile testing provides an explicit measure of material strength, conservators are unable to tare a piece of painting to create the samples (required length of 250 mm), therefore the traditional methods of assessing mechanical properties have been visual cues and pH values.
mechanical properties in canvas conservation understanding the mechanical properties of art canvases is necessary for art conservation especially when deciding on transporting paintings conservation treatments and environmental specifications inside museums canvases are layered structures made from weaving fibers together where each layer responds differently to changes in humidity resulting in localized stresses that cause deformation cracking and delamination there are two directions to the canvas the warp direction (threads run vertically) and the weft direction (threads run horizontally) researchers performed tensile testing to determine the effects of humidity on the strength of canvases and observed that increasing humidity decreased the effective elastic modulus (combined modulus of the weft and warp directions) for example the effective modulus at 30% relative humidity is 180 mpa which drops to 13 mpa at 90% relative humidity suggesting that canvas is becoming more flexible and susceptible to deformation there is an inherent anisotropy to the elastic modulus measured in the weft and warp direction as evidenced in the strain vs load behavior of the canvas the canvas exhibits a 01 strain in the weft direction and 02 strain in the warp direction before failing (thread ripping apart) though tensile testing provides an explicit measure of material strength conservators are unable to tare a piece of painting to create the samples (required length of 250 mm) therefore the traditional methods of assessing mechanical properties have been visual cues and ph values