Mini-Encyclopedia of Papermaking Wet-End Chemistry
Part Two: Definitions and Concepts

Ash

Papermakers use the word "ash" in two ways. In its most general sense, the word means "filler" or "mineral content." The word also refers to the material that is left over when paper is incinerated at a defined temperature and for a defined time. A relatively high temperature of incineration, such as 900 degrees Centigrade, can drastically change the chemical composition of the filler. For instance calcium carbonate is converted to CaO, which has a mass only 56% that of the filler. Kaolin clay looses water under such conditions; the anhydrous clay has 86% the mass of the hydrous filler clay. A moderately low temperature of incineration, e.g. 500 degrees Centigrade, may leave most of the filler in its original form. To convert "percent ash" data to "percent filler" it is necessary to know the relative amounts of the different fillers and their respective losses on ignition. The relative amounts of, say clay versus calcium carbonate, can be determined by x-ray fluorescence analysis of the incinerated ash.

Request from the webmaster: Our goals include brevity and accuracy. Hopefully we have succeeded with the first goal without sacrificing the second. Please let us know right away if you find an error or omition. Also, please indicate points that need a clearer description.


RETURN TO INDEX PAGE OF ENCYCLOPEDIA

Home page Research opportunities Business opportunities Background information Links to wet-end chemistry E-Mail
This page is maintained by Martin hubbe, Associate Professor of Wood and Paper Science, NC State University, m_hubbe@ncsu.edu .