72 Chapter 4
hemicelluloses and lignin. The Victorysail samples had a higher acid content;
for some yarns this increase was only marginal, while others had more than a
10-fold raised acid content, and in the case of a few heavily deteriorated spe-
cimens, a much-increased acidity was observed. These results contrast with
the surface pH data, which suggested a similarly raised acidity across the
whole sail. One interpretation of this anomaly is that in cases where the yarn
acid content is lower, the acid is localised in the outer regions of the fibres, and
that as theacid content rises it is found deeper within the fibres. This would be
consistent with an initial surface oxidation, followed by the progressive dete-
rioration of the secondary cell walls of the fibres. Titration implies that the
majority of this acid is weak, derived from the oxidation of cellulose and
other fibre constituents, which would fit with this hypothesis.
3.5 Conservation and Display of the VictoryFore Topsail
Before any treatment the sail was placed in an environmentally-controlled
chamber and allowed to acclimatise under conditions of moderate humidity,
where the fabric would be the most pliable. In the first phase, the conservators
then surface cleaned the Victorysail with low suction vacuum cleaners and
static cloths, removing a considerable quantity of particulate soiling. This not
only improved the look of the sail but also reduced the risk of abrasive wear.
Taking account of the need to handle the fabric gently and prevent undue stress,
the sail was laid flat (over Tyvek®, an inert high density polyethylene sheet,
on a suitable platform), and an inflatable roller was specially constructed to
help to move the large artefact within a relatively confined space. There was then
negligible risk of uneven short-term loading which could have ruptured the
fabric.
Our mechanical tests suggested that it would be inadvisable to hang the sail
from a yard, in the manner originally used onboard ship. Instead, it is more
appropriate to display the artefact on a suitable frame that will support the
weight of the fabric and prevent fibre slippage and permanent deformation. In
terms of the sail’s continued preservation, the apparent undue acidity of the fab-
ric also needs to be borne in mind. Since, over the longer term, acid deteriora-
tion products can become mobile and may even be evolved in gaseous form,
adjacent materials could become affected. This suggests that it is best to keep
the sail unfolded and in an air conditioned environment to prevent any build-
up of acidic gases, though for storage it might be appropriate to include acid
sorbents between the layers of the cloth. Since some fibres are already quite
acidic, deacidification also needs to be considered in the future. After weigh-
ing up the relative risks, non-intervention may be deemed the more appro-
priate course, avoiding the structural damage that might be caused by the
deacidification process. More research is required to inform this key decision.