5 CONCLUSIONS

1. Correlations between pH, calcium content, and gelatin content in the 35 historical specimens tested suggest all three variables make a contribution to increasing L∗ value (lighter color). This finding, in turn, suggests the three may interact in a chemical and physical system that has an overall positive effect on the long-term stability of paper.
2. It is not possible to state from these data that any one variable makes a more significant contribution to higher L∗ values.
3. Gelatin is an important component in the chemical and physical systems of papers made in Europe between 1400 and 1800 that deserves additional research attention. Such work can be significant to conservators of rare books and works of art on paper with regard to the advisability of washing, aqueous deacidification, and resizing treatments.