The kinetics of the formation and condensation of mono- and dimethylolureas and of simple UF condensation products has been studied extensively. The formation of mono- methylolurea in weak acid or alkaline aqueous solutions is characterized by an initial fast phase followed by a slow bimolecular reaction [4,5]. The first reaction is reversible and is an equilibrium which proceeds to products due to the uptake of the products, the methy- lolureas, by the second reaction. The rate of reaction varies according to the pH with a minimum rate of reaction in the pH range 5 to 8 for a urea/formaldehyde molar ratio of
1:1 and a pH of 6.5 for a 1:2 molar ratio [6] (Fig. 1). The 1:2 urea/formaldehyde reaction has been proved to be three times slower than the 1:1 molar ratio reaction [7].