Damage assessment and preservation of an Egyptian silver vase (300 - 200 B.C.)

Damage assessment and preservation of an Egyptian silver vase (300 - 200 B.C.)

Wanhill, R.J.H.
Leenheer, R.
Steijaert, J.P.H.M.
Koens, J.F.W.

National Aerospace Laboratory NLR

1995-11-01

An Egyptian metal vase from the Ptolemaic period was investigated metallurgically and fractographically. The metal is nearly pure silver, and chemical analysis indicates it was obtained from the cupellation of lead. Despite its high purity (in archaeological terms) the metal is severely cracked and embrittled, with fractures mainly along grain boundaries. Factors contributing to this damage are work-hardening and residual deformation in the microstructure (slip and twinning), corrosion along slip lines and twin boundaries, corrosion in bands that are the remains of coring (solute element segregation during solidification), large equiaxed grains, externally applied forces and internal residual stresses. The metal is now easily broken into small pieces, i.e. it is friable. This must be taken into account during any further restoration of the vase. A procedure to better preserve the vase is suggested. A joint publication of the National Aerospace Laboratory NLR and the Allard Pierson Archaeological Museum of the University of Amsterdam.

archaeology
corrosion prevention
fractography
grain boundaries
cracking (fracturing)
damage assessment
metal shells
silver

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Nationaal Lucht- en Ruimtevaartlaboratorium

Campus only

NLR Technical Publication TP 95372 U

Aerospace Engineering Reports

report

(c) 1995 National Aerospace Laboratory NLR