"The Kappa number" is the topic of the tenth issue of the Technical Knowledge Folder series.
The »Kappa number» is a characteristic figure obtained from pulp testing. It is used to determine the residual lignin content in mechanically or chemically treated fibre pulp.
Materials for permanent preservation must comply with the technological principles of the EN ISO 9706 and ISO 16245 Type A standards. In point 5.4 of the standard EN ISO 9706, reference is made to "oxidation resistance": "The paper must have a Kappa number below 5.0, measured as described in ISO 302, with the modifications specified in Annex A of this international standard."
Read more about this in the digital edition of the current Technical Knowledge Folder.