One of the most common foaming soils, or the new generation oils and coolants that contain surfactants inside of them, is the water-soluble coolants that are essentially emulsions. They work by surfactant technology as well. If you’re using water-soluble coolant, you’re automatically adding some level of surfactant into your bath. A second way that you can add in a lot of surfactant without knowing it is in the green movement, using a vegetable oil or an animal fat as they store natural oil. Fats are actually the way we used to form soap way back in the day. Most of our parts washing detergents are alkaline so when you introduce that alkaline soap into a natural oil, you get a saponification reaction and every time you do that, you’re creating more and more surfactant. Those soils especially tend to foam out of a washer before anyone knows what’s going on.