Used a kit for cleaning oven shelves - basically a large very robust plastic bag with a zip seal and a bottle of caustic solution mixed with detergent.
It did work very well at cleaning the shelves.
The final instructions to dispose of the used caustic liquid were roughly "Partly fill the bag with water, swill round, tilt bag to gather liquid in one corner, cut off other corner and tip bag to empty liquid down the sink.".
Errr....right, yeah.
Trash the bag.
Otherwise I would have a nice plastic bag for future use and just have to make up my own caustic solution.
However, kiddies, always follow the instructions.......
Or not.
Dave R