Investigation of the effects of reburial on artefacts made of ceramics and glass
Institution
National Heritage Board (Riksantikvarieämbetet)
Box 5405, 114 84
Stockholm, Sweden.
Co-ordinators
BA, BSc Carola Bohm, carola.bohm@raa.se
BA, BSc Eva Christensson, gla@raa.se
Aim
The aim of this project is to investigate how the underwater environment
in the harbour of Marstrand lends itself to reburial of ceramic and
glass marine archaeological artefacts. The purpose of the study is
to obtain measurable data to enable informed decisions as to which
types of ceramic and glass artefacts might be suitable for the kind
of long-term storage implied. Furthermore, the impact on the artefacts
of a variety of packaging materials is an important part of the study.
.
Materials and method
A broad variety of ceramic wares excavated from
the frigate ‘Fredricus’-
earthenware, stoneware, flintware and clay pipes is included in the study,
as well as glass of varying quality and degree of deterioration. To enable
a relevant assessment of any alterations of the test material during
reburial, a reference material consisting of modern samples is also included.
The glass samples are specially prepared model glasses of two different
compositions, a soda glass of balanced composition and a potash glass
with high K/ high Ca. For ceramic references a variety of 20th century
wares is used.
To retrieve the material at set intervals during the planned 50-year
period, 7 separate batches of samples were deposited in 2002. Each batch
includes 3 types of packing material (sealed PE Zip-lock® bags, permeable
PE netting and semi-permeable PP/PE geotextile) for each sample category.
12 categories of samples, 6 archaeological and 6 modern samples, were
deposited in each type of packaging. All samples of each category were,
as a rule, cut from the same object. In addition, some fragile glass
objects were included to test packaging for mechanical support. One complete
batch of samples is kept for reference in ambient storage conditions.
Processing and Analysis
Prior to reburial all samples were documented, weighed and photographed.
Processing of each retrieved batch of samples involves light cleaning,
controlled drying, weighing, microscopic examination and elemental
analysis with SEM-EDS. The unexposed reference samples are used as
comparison to monitor alterations in the reburied material and all
samples will in turn be saved for future reference. If appropriate,
further analyses may be considered along the way.
Work
in progress and
results 2003
Carola Bohm
Eva Christensson