REFERENCES

Burgess, H. and Hanlan, J., “The Degradation of Cellulose by Bleaching,” Journal of the International Institute for Conservation—Canadian Group, Vol. 4, No. 2 (1979): pp. 15–22.

Burgess, H., “The Colour Reversion of Paper After Bleaching,” preprints of the Institute of Paper Conservation Cambridge Conference, 1980: pp. 171–183.

Rapson, W. H., ed., The Bleaching of Pulp, Technical Association of the Pulp and Paper Industry, New York (1963): p. 301.

The dissociation constant of hydrogen peroxide in an aqueous solution at 25�C is 2.4 � 10−12. Discussion of the perhydroxyl anion as the active bleaching species is presented in Rapson, The Bleaching of Pulp (op. cit.): p. 180.

Schumb, W.; Satterfield, C.; Wentworth, R., Hydrogen Peroxide, Rheinhold Publishing Corp., New York (1955): Chapter 8.

When the gas which formed within the blisters was exposed to a small glowing splint of wood, the wood immediately underwent very rapid combustion, indicating the presence of oxygen.

To see whether a particular print was prone to blistering during hydrogen peroxide bleaching, a small section of the sheet was placed in a 2% solution of peroxide in water (pH = 10). The papers which blistered were chosen for the experiment.

The recommendation for calcium hydroxide (or magnesium bicarbonate) pretreatment is found in: Hey, M., “Paper Bleaching: Its Simple Chemistry and Working Procedures,” The Paper Conservator, Vol. 2 (1977) P. 20. The use of a 50% saturated solution of calcium hydroxide is suggested in:Hey, M., “The Washing and Aqueous Deacidification of Paper,” The Paper Conservator, Vol. 4 (1979): p. 70.

In the author's opinion, this solution is too alkaline for routine treatment of works of art.

The water was deionized with a Barnstead Combination Cartridge. All chemicals were Fisher Scientific Reagent Grade.

A pH of 10 was chosen because it allowed comparison with Ms. Burgess' stabilized bleaching bath, where a pH of 10 is specified. (See #1 of #2 above.)

Burgess, H., “The Colour Reversion of Paper After Bleaching,” (op. cit.): p. 172.

In this case, the resulting concentration of hydrogen peroxide in water and ethanol was less than 2%. It was decided for the purposes of the experiment not to consider the alcohol as part of the solvent since in preliminary tests it seemed to be a relatively inert component in the peroxide-water-alcohol-ammonia bleaching bath.

Diffuse reflectance measurements were taken using a Pye Unicam SP8-100 spectrophotometer equipted with a diffuse reflectance accessory (an integrating sphere type conforming to C.I.E. recommendations) and a barium sulfate white reflectance standard. The reflectance measurements were the same whether the supporting layer behind each sample was white or black. The wavelength of 416 nm was chosen because it allowed comparison with work done by Ms. Burgess. Also, when some full spectrum readings of paper and after bleaching were studied, it was observed that the greatest changes in reflectance did occur in the blue part of the spectrum near 416 nm.

Schumb, W.; Satterfield, C.; Wentworth, R., Hydrogen Peroxide (op. cit.): p. 535.

In the interest of brevity, and because the amount of brightening due to alkalinity was small, the data obtained with these controls are not considered in this paper. Complete data may be obtained from the author.

P.Holladay and R.Solari mention in The Bleaching of Pulp (op. cit.: p. 191) that catalase is formed by the metabolism of bacteria which are found in some paper pulps. The production of this enzyme is of concern to papermakers because it accelerates hydrogen peroxide decomposition and therefore reduces bleaching efficiency. It would be interesting to see whether this enzyme plays a role in the more vigorous decomposition of hydrogen peroxide noted in degraded paper.