>>where my parents would pour bacon grease and other oils. This was never used. I don’t know what they did with it.
Funny I picked up that habit from my parents (they were both children during the Great Depression). I always thought it was to cut down on the grease build-up in the plumbing when it cooled going down the drain. Or maybe it had to do with septic systems.
Never thought it was for some other use.
...grease build-up in the plumbing
Actually, through my readings about The Home Front, during WWII, the grease was collected for something. Too much Scotch has temporarily clouded my memory, but I think it had something to do with munitions manufacture. The grease was collected by the same guys who took away your legacy heirloom bicycles, pots & pans, oil lamps and Victola phonographs for the war effort.
Other FReepers can fill in the details...