Reply To: Forth Mill -Kilbagie

Alkaline Paper making

Kilbagie Mill (together with Wolvercote Mill)  in the late 1970s and early 1980s was in the forefront of replacing rosin size with AKD alkaline size.

This paper A Review of Paper Quality and Paper Chemistry JC Williams 

reflects the enthusiam of the Technical Manager, Hugh Bryson:

The major portion of the American paper industry has continued to make rosin-alum-sized acid impermanent paper. European paper- makers, however, have been more responsive. Gestetner Papers Ltd. in Scotland is producing excellent calcium carbonate filled papers. Hugh Bryson, Process and Technical Manager for Gestetner, has been helpful and generous in sharing his experiences:
The considerable upsurge in the last five years of non-rosin derivatives for neutral sizing of paper, coupled with the use of calcium carbonate fillers, has opened a new realm of papermaking. Neutral- sized, calcium-carbonate-loaded papers are now firmly established in the European market, not only, as was originally thought, for specialty lines, but competing successfully in the popular lines of lithography (stationery sizes as well as conventional litho sheets), industrial papers, chart papers, continuous stationery, archive text, photocopying, and coated stock (on machine-blade and off-machine coated). What has the technique of neutral, i.e., non alum-rosin sizing to offer? The answer is very simple, better paper at a lower cost.

In a letter, Bryson added: FALL 1981 209

Economics-Brilliant!-and getting better each year as the cost of energy rises, that is in comparison with non-alkaline paper-making. At present, we see a 32% reduction in energy in comparison with acid paper-making. [There is] a reduction in the number of drying cylinders one would normally use for acid paper-making due to the ease of drying the increased carbonate filler one can more readily carry in an alkaline system. The reduction in oil, water and steam makes the picture an even greater financial success, and the big punch line [is] no capital investment to change to neutral sizing and carbonate filled papers. Specia1 equipment-Paper-making-w ise- none; laboratory-wise- nothing that is not normally found in progressive technical laboratories, whether they are acid or alkaline paper mills.

21 Samples of Gestetner paper have been given accelerated aging tests at the Library of Congress Preservation Research and Testing Laboratory and found to have an excellent life span.

It was not as simple as it sounds. Betz UK were the biocide suppliers and struggled to control the microbiology of the new system, despite biocides that were far more toxic than those available now. At one stage they resorted to Acrolein imported specifically from America. The literature often erroneously refers to alkaline mills having fungal problems. This was because, at Kilbagie, the suppliers wrongly identified Sphaerotilus natans as fungi.