Learning Objectives
Know the meaning of the term ‘overdyeing’.
Interpret mathematial models to explain why overdyeing occurs below pH3.5

Consolidation Questions
1. What is the meaning of the term ‘overdyeing’?
2. Give 2 reasons for overdyeing occurring when acid dyes are used on nylon.
3. Use the graphical representation of mathematical models, and the chemistry of the dyes themselves, to exlain why overdyeing is likely to occur at a pH below 3.5.