The effect of time was less pronounced for more concentrated solutions since its maximum value had been reached from the beginning of the test (41.5% & 40% loss in weight after one hour for 40% NaOH, compared to 19.8% & 18.4% at the same timing for 10% NaOH) for CA produced from flax fibers and cotton linters respectively. It is clear from the results that the resistance of CA, produced either from flax fibers and cotton linters to alkalies, is nearly the same; however, CA produced from both residues had a poor alkalis resistance when compared to commercial CA which have a good resistance factor (=3) for strong alkalis (Granta Design Limited, 2014). However, the poor alkali resistance was due to the presence of hydrolysable ester bonds in the structure of acetate.