Under certain conditions the hand-made papers manufactured
from rag fibres are exposed to attacks
of micro-organisms thus suffering the degradation
of cellulose content in fibres. Papers so contaminated
are gradually loosing their original mechanical
strength. *
At the end of the 19th century a method has been
found for strengthening of weakened papers by their
lining with artificial parchment glued on by means
of the starch glues. However, with the passing time
artificial parchment is getting more and more brittle
and looses its transparency whereas its removing
from the weakened paper becomes very difficult and
causes several considerable troubles.
The weakened papers can also be laminated with
silk chiffon or Japanese tissue paper, but here the
faults common for the both methods of lamination
consist in — difficulties to strip the linings from
their beds in the case of need, advancing flavescence,
loss of mechanical strength, and the susceptibility
of starch glues to the action of micro-
organisms and insects. All the above factors necessitate
the considering of possibilities to apply other
methods of lamination for hand-made papers. Method
of lamination using acetylcellulose foil worked
out by Barrow and its modifications applied successfully
in several countries can be considered as proper
one for lamination of machine-made papers, and in
particular those containing groundwood. However,
the hand-made papers change their texture apparently
after processing of their surfaces.
Lamination with the use of acetylcellulose foil partially
solved in acetone appears to be a better method
in application for old papers since it eliminates
the need for high temperature and pressure but the
acetylcellulose foil of high quality is required for
this purpose. In the National Main Archiv of Old
Record, Warsaw a method has been developed for
lamination using the acetone solution of a c e ty lcellulose.
The solution is rubbed on the paper and
tissue paper by means of a painter’s brus/h enabling
to laminate the paper on both sides or on one side
only. However, the lamination on both sides is
more labour-consuming operation and leads to the
increased paper thickness but at the same time
provides the higher mechanical strength. In the
course of lamination by means of acetylcellulose
acetone solution the toxic and highly inflammable
vapours arise.
Similar to the above method is lamination using
the methylcellulose solution. The aqueous solution
of methylcellulose is entirely odourless. The principle
of lamination procedure is much the same as in
the case of starch glue lamination with this sole
exception that paper laminated with methylcellulose
is much more resistant to the attacking microorganisms
and at the same time shows considerable
improvement of its mechanical strength.
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