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The benefit of a tough skin: Bullet holes, weathering and the preservation of heritage

Gomez-Heras, Miguel; Brassey, Charlotte; Green, Owen; Mol, Lisa; Blenkinsop, Thomas


Miguel Gomez-Heras

Charlotte Brassey

Owen Green

Lisa Mol
Senior Lecturer in Physical Geography

Thomas Blenkinsop


© 2017 The Authors. Projectile damage to building stone is a widespread phenomenon. Sites damaged 100 years ago during the First World War still see daily use, while in a more contemporary setting numerous reports show the damage to buildings in Babylon, Mosul and Palmyra. While research has been carried out on the long-term effects of conflict such as fire damage, little is known about the protracted damage sustained through the impact of bullets, shrapnel and other metal projectiles outside of the field of engineering focused on ceramics and metals. To investigate alterations to mineral structure caused by projectile damage, impacts were created in medium-grained, well-compacted, mesoporous sandstone samples using 0.22 calibre lead bullets shot at a distance of 20 m. Half these samples were treated with a surface consolidant (Wacker OH 100), to mimic natural cementation of the rock surface. These samples were then tested for changes to surface hardness and moisture movement during temperature cycles of 15–65°C. Petrographic thin section analysis was carried out to investigate the micro-scale deformation associated with high-speed impact. The results surprisingly show that stress build-up behind pre-existing cementation of the surface, as found in heritage sites that have been exposed to moisture and temperature fluctuations for longer periods of time, can be alleviated with a bullet impact.


Mol, L., Gomez-Heras, M., Brassey, C., Green, O., & Blenkinsop, T. (2017). The benefit of a tough skin: Bullet holes, weathering and the preservation of heritage. Royal Society Open Science, 4(2),

Journal Article Type Article
Acceptance Date Jan 27, 2017
Online Publication Date Feb 22, 2017
Publication Date Feb 22, 2017
Deposit Date Feb 6, 2017
Journal Royal Society Open Science
Electronic ISSN 2054-5703
Publisher Royal Society, The
Peer Reviewed Peer Reviewed
Volume 4
Issue 2
Article Number 160335
Keywords benefit, tough, skin, bullet, holes, weathering, preservation, heritage
Public URL
Publisher URL


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