A "hardening agent" is that one (or more) ingredient you use in your recipe to make your lotion bars and lip products solid.
Remember to always adjust your formulas if switching from Beeswax to a vegan recipe. The higher the melting point the less you need to add.
Ucuuba and Japanese Wax are not hard enough to be the only hardening agents for lotion bars and tube lip products, but they work just fine for balms, salves and scrubs.
