Those constituents which have consistently been found associated with instability in paper are groundwood, high acidity and alumrosin size. Stable, durable papers must be free from groundwood, alum, alum-rosin size and have a pH of 6.5+. This publication explores the collective use of color spot tests to distinguish stable from unstable book and record papers. Many samples of four different kinds of paper were used in this study, writing papers widely used in the United States, uncoated book papers, coated book papers and magazine papers. 72% of the papers had a pH below 6.5. The test for the presence of groundwood is phloroglucinal, for acidity it is Chlorophenol Red, for alum it is aluminon, for rosin it is sugar water followed by sulphuric acid. The results of the tested papers are evaluated and there are tables. 100 testing kits are offered. There is a spot test color chart in the booklet. -- AATA