So called acidic paper is vulnerable to aging. To control degradation, there are two ways. One is to make neutral paper and another is to neutralize acidic paper. Several processes for neutralization or deacidification have been proposed. Mass deacidification by diethyl-zinc was patented by the Library of Congress, U. S. A.
The authors have been studying the diethyl-zinc process in detail. The effects of the process on retention of various properties on papers from 65 books published since 1911, as well as five different papers were investigated through an accelerated aging at 80°C and 80% R. H., and following results were obtained.
(1) No significant change in strength and optical properties was noticed on papers after diethyl-zinc treatment before aging.
(2) Diethyl-zinc was effective to reserve strength such as MIT fold under a tention of 300 gf after two weeks accelerated aging, but seemed ineffective in some cases of aged papers. However, it was found still effective when MIT fold was measured under a tension of 20 gf.
(3) So far retention of brightness after an accelerated aging, the diethyl-zinc treatment seemed about ineffective to aged papers.
