Showing posts with label fading. Show all posts
Showing posts with label fading. Show all posts

24 April 2010

Thesis: Discoloration in Renaissance and Baroque Oil Paintings (2002)


Title
: Discoloration in Renaissance and Baroque Oil Paintings. Instructions for Painters, Theoretical Concepts, and Scientific Data

Author
: M. H. van Eikema Hommes

University
: University of Amsterdam

Year
: 2002

Pages
: 223

Type of document
: Thesis

Link
: http://dare.uva.nl/... (pdf)


From the Introduction:
Presently, the problem of the degradation of old oil paints is the research domain of conservation science, namely the science investigating the cause of ageing processes in works of art and developing methods of retarding or countering them. Researchers focus on uncovering the chemical and physical characteristics of oil binding media and pigments. The composition of paints in old paintings is painstakingly analysed to this effect. On the basis of the results, paint systems are made that approximate as closely as possible the original composition of the old paints in the aspects deemed relevant by the researchers. By exposing these reconstructions to artificial ageing, an attempt is made to accelerate the natural ageing processes. When chemical and optical changes are charted, useful information can be acquired about the degradation processes that have occurred in the old paints. [...]

Table of contents (short version):

I. A Proposal for the Classification of Painting Methods and Recipes

II. Painters' Methods to Prevent Colour Changes Described in Sixteenth to Early Eighteenth Century Sources on Oil Painting Technique

III. Discoloration or Chiarsoscuro? An Interpretation of the Dark Areas inn Raphael's Transfiguration of Christ.
IV. Verdigris Glazes in Historical Oil Paintings: Recipes and Techniques
V. Indigo as a Pigment in Oil Painting and the Problem of its Fading


22 April 2010

Article: Measurement of Light Sensitivity with Micro-fading Tests (2002)

Title: Pursuing the Fugitive: Direct Measurement of Light Sensitivity with Micro-fading Tests
Author
: Paul M. Whitmore

Reference
: in The Broad Spectrum: The Art and Science of Conserving Colored Media on Paper, H. K. Stratis and B. Salvesen (ed.), Archetype Publications, London, 2002, 241-243

ISBN
: 1873132573

Link: http://www.cmu.edu/... (pdf, 245 Kb)



18 April 2010

Article: 'Virtual Fading' of art objects (2007)


Title: 'Virtual Fading' of art objects: simulating the future fading of artifacts by visualizing micro-fading test results
Author: Hannah. R. Morris and P. M. Whitmore
Reference: Journal of the American Institute for Conservation 46, 2007, 215-228
Link: http://www.cmu.edu/... (pdf, 590 Kb)

Abstract:
The authors examine the importance of visualizing the color changes of colorants exposed to visible light, and use this information to create a “virtually faded” art object. The color information collected during lightfastness measurement (as CIE L*a*b* values) with a micro-fading tester can be transformed to RGB values, and color swatches representing the original and faded colors displayed on a computer monitor. Such demonstration of the appearance changes can help to visualize the degree of color change and the precise nature of that change, which may not be simple lightening of the color but could also include hue or chroma changes. Judging the visual impact of a light-induced color change requires viewing the altered color in its context within a particular image. Digital renderings of paintings were created with Adobe Photoshop and Matlab, using a number of fugitive colors, the fading characteristics of which had been recorded with prolonged micro-fading tests of 100–1920 minutes in duration depending on the light dosage required for the color to no longer be hanging. Based on this information describing the appearance of each of the colors as it changes with light exposure, simulations of the “virtually faded” painting were generated, representing the image appearance with incremental light exposure. Such virtually faded simulations can offer insight into the severity of particular light-induced color changes, allow targeting of crucial color areas that might warrant tracking in a color monitoring program,and inform discussions about the “end of exhibition life” of an object and appropriate exhibition rotation policies.