FMC Corporation, Besemer City, NC, USA has developed a mass preservation chemical treatment process that not only neutralizes the acid in paper to extend the document's useful life but also strengthens the damaged pages, to enhance the usability of the document. Documents treated by the FMC process are virtually indistinguishable from untreated ones. To determine the quality of treatment, and compare the ability of alternative mass preservation technologies to enhance and extend the useful life of documents, FMC published a proposed evaluation strategy in February 1990. This article summarizes the evaluation strategy, describes the FMC process and communicates the results of independent laboratory testing conducted on FMC's mass preservation process. The results demonstrate that the FMC process significantly improves the chemical and physical properties of paper following accelerated ageing.