On November 15, Suzhou Archives carried out an acidification research on the historical archives in the collection. Reli Heritage Preservation took part in the research and conducted archive acidity examination.

During a working period of 3 days, technicians from Reli Heritage Preservation conducted detection on 25 sample archives according to TAPPI T529 om standard, and performed spray deacidification and verification on one batch of archives.

In Bookkeeper deacidification effect verification, average pH value of samples detected before deacidification was 4.29; Re-detection after 24 hours from deacidification process showed that average pH value rose to 7.95. A clear sign of alkaline state and a significant deacidification effect.

Publishing dates of historical archives of this sampling test cover from 1916 to 2001. Among which, 23 archives , 92% of the sampling, were rated damaged by acidification status.

Analyzed from time line: average pH value of archives prior to 1949 was 4.62, while average pH value of archives after 1949 was 5.18, yet average pH value of archives after 1990 was 5.15.

According to paper category: manual paper archive 1 copy, pH value read 7.41; machine made paper in 12 pieces with average pH value of 4.65; and 12 pieces of newsprint with average pH of 4.73.

Archival documents are historical records with evidence value. The investigation of acidification will provide scientific and reliable data reference for deacidification protection of historical archives in the future.Reli Heritage Preservation will work hard with collection agencies, introducing advanced technology of the world, save precious documentations in China.