Conservation Science

78 Chapter 4

in terms of silk preservation as many of them act to catalyse degradation reac-
tions. In addition, the processes used to apply the materials can also lead to
damage (e.g.the use of acidic baths). Consequently, many historic silks, espe-
cially 19th and early 20th century European silk artefacts, are in a relatively
poor state.

4.3 The Condition of the Shackleton Ensign

Once released from its frame, the true condition of the ensign was revealed.
Immediately apparent were the vivid colours of those areas that had been pro-
tected from light compared with the faded tones of the exposed regions. The
extreme fragility of the fabric was evident. There were splits where the flag
had been folded, as well as numerous smaller fractures and several areas of
complete loss (Figure 12). Closer examination highlighted the highly degraded
nature of the silk fibres, characterised by thinning, brittleness and various pat-
terns of breakage. The majority of the damage was concentrated in the areas
of the cream-white silk; bleaching or finishing treatments applied to this silk
at the time of manufacture could have directly damaged the fibres or rendered
them the more susceptible.
To test this hypothesis in part, we subjected individual loose threads from the
ensign to X-ray microanalysis in a scanning electron microscope. Characteristic
X-rays are emitted from the constituent atoms of a specimen as a result of elec-
tron-beam induced core electron ionisation processes. The X-ray spectrum
resulting from the cream-white silk threads indicated quite heavy tin weight-
ing (Figure 16); the coincidental presence of silicon and phosphorus suggests

Energy/keV

0.80 1.60 2.40 3.20

P

S

Sn

O Si

C

4.00 4.80 5.60 6.40 7.20

Figure 16The X-ray spectrum generated by a cream-white silk thread from the Shackleton
ensign when probed in a scanning electron microscope