Commodity storage in covered hoppers

[Puddlejumper]

That was a very good explanation. This was also done with coal, as there were multiple grades of coal that would be stored in a yard. The grade was tracked by the car number. Depending on what the customer ordered, cars of a specific grade, or combination of grades, would be pulled in order to satisfy the customer's demand.

I wonder, does GERN have different grades of granulated flux? Perhaps food-grade and industrial-grade?