
Originally Posted by
greennotebook
This really wouldn't be a very difficult potion, would it? In cooking, you might add flour or starch to a gravy to start thickening it, or you could add pureed vegetables or some dairy products like sour cream or milk to soup. Honestly, the idea of adding a solution to liquids to thicken them feels counter-intuitive.
Do you need to make a potion for this? Could you instead have a lesson on general techniques used to thicken potions using a few different hands-on problem-solving examples? Students who know a few general principles could figure out how to apply them to a few different potions.
If you need a thickening potion for a plot device, however, maybe there's some sort of paralyzing venom you could use as an ingredient. Something that makes a human feel as though s/he is thickening, or the air is thickening around him/her, might have a magical affect on potions.