Mixing instructions for two-part epoxies and urethanes mention a potlife of so many hours. Does this mean the paint turns solid in that amount of time?

In some high-solids materials, the liquid will become solid at the end of the potlife. In most cases, though, the potlife refers to the amount of time you have to apply the coating before it gets to a critical point in the chemical reaction between the two parts. After the potlife period expires, the material will become difficult to apply and the adhesion, cure, and performance of the coating will be adversely affected. When working with these types of products, it’s best to mix only what you can use within the potlife listed by the manufacturer.