Rillieux’s innovative design for a vacuum pan.

Where the material in the vacuum pan is to be bleached, it is well to introduce this reagent just before striking grain, thus furnishing a bright clear material which will act as film over the nucleous of sucrose in the grain.

This method, known as vacuum pan refining, is the most costly and energy-intensive, but it creates a product that's nearly 100 percent sodium chloride.

Some solar sea salt is then washed and refined in a process that can be as energy-intensive as vacuum pan refining.

Kosher salt can be extracted via solution mining or from seawater and processed via vacuum pan refining or solar evaporation.