Laminacja papierów czerpanych

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.