Q&A: Why can cationic and anionic ingredients be used together in solid shampoo bars?

In this month’s Q&A, Melinda asked, Why can cationic and anionic ingredients be used in solid (shampoo) bars? Normally, we don’t want to combine anionic (negatively charged) or cationic (positively charged) ingredients together as they’re opposite charges and don’t play well together. But we can make them work because we don’t have all that annoying water…