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Effects of reinforcements on the preservation of paintings on work panel

Brewer, J.A. (1998). Effects of reinforcements on the preservation of paintings on work panel. (Unpublished Doctoral thesis, City, University of London)


To evaluate reinforcement design, this thesis combines observations on panel paintings, interviews with panel specialists, conservation records, and deformation analyses of constructed mock-ups of thinned panels bearing a selection of reinforcements. Reinforcements were reviewed, classified, and damaging effects discussed, with particular emphasis on the role of attitudes toward flattening of panel paintings. Mock-up surface deformations were then recorded during controlled changes in relative humidity (RH) using digital photogrammetry, moiré fringe analysis, and raking-light photography.

Results for unreinforced panels emphasised that wood movement causes deformations, not just in the transverse- grain direction, but in three dimensions, which must interact with reinforcement. A consistent pattern of overall panel warp was shown which decreases in rate and amplitude with increasing panel thickness, including considerable warp parallel to the grain, heretofore ignored.

Important results for reinforced mock-ups showed that during changes in RH, in-plane restraint by reinforcements such as laminates or battens fixed to the panel back causes bending in the opposite sense to that in which warp would occur in an unreinforced panel. For relatively rigid and sliding reinforcements, in-plane movement in the transverse-grain direction at the panel surface appears to be increased by restraining warp in a flat plane. Use of more flexible reinforcements should reduce associated stresses.

For cradled panels, a pattern of strain exists on the coated side which corresponds with cradle structure. Combining this information with recorded out-of-plane deformations and examples of panel paintings with cradled- related damages, "washboarding" and related deterioration were explained in more detail than before.

Reported twists or concave deformations soon after lamination with balsa and wax-resin adhesive/mortar are attributed to contraction during cooling and solidification of molten wax-resin.

Design improvements are suggested such as encouraging use of more flexible reinforcements. Marking their first application to art conservation and in particular to analysis of panel painting deformations, digital photogrammetry and moiré fringe analysis were shown to be very suitable techniques.

Publication Type: Thesis (Doctoral)
Subjects: N Fine Arts > ND Painting
T Technology > TA Engineering (General). Civil engineering (General)
Departments: School of Science & Technology > Engineering > Civil Engineering
School of Science & Technology > School of Science & Technology Doctoral Theses
Doctoral Theses
[thumbnail of Brewer thesis 1998 redacted PDF-A.pdf]
Text - Accepted Version
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