ABSTRACT
Stage 1: e initial (primary) stage of attack is a process that involves ion exchange between alkali ions from the glasss and hydrogen ions (H+) (or hydronium (H3O+) ions) from the solution, during which the remaining constituents of the glass are not altered. Reaction (1) in Figure 20.3 tends to dominate during Stage 1 attack. During Stage 1, the rate of alkali extraction from the glass is parabolic in character (Lyle 1943, Zagar and Schillmoeller 1960, Rana and Douglas 1961), as shown in Equation 20.1.
