Maps, deacidification

In this section, data are presented on the effects of deacidification on (a) oxidizable material extracted from some old papers (b) changes in physical properties of these old papers and (c) changes in physical properties of several multicolored maps. The results of some experiments on the interaction of metal ions with a hardwood kraft pulp are given, and discussed in relation to deacidification and probable stability. A series of handsheets made from a hardwood kraft pulp, after treatment of the pulp with various metal ions, were studied in relation to the effects of deacidification on the removal of aluminum and on stability before and after... 

Table XV. Effect of Deacidification with Magnesium Carbonate for Thirty Minutes on the Tensile Properties of Six U.S. Geological Survey Maps and a Civil War Map...

The pH values of the maps before deacidification are surprisingly high. This is in keeping with the data developed by Smith (51) who studied the effect of deacidification on maps. The pH values after deacidification are not nearly as high as the pH values of the old papers after deacidification. These maps apparently contain a buffer that was built in during manufacture. 

The pH values of the maps before deacidification were in the neutral range, and treatment with magnesium bicarbonate did not result in high pH values—8.5 was the maximum. 

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