Approximately 1/8 tsp gel food coloring (Wilton or Americolor)
Salt, to taste
In a 5qt pot that has a lid, heat the oil on medium-high heat until hot.
Add the sugar, food coloring, and popcorn kernels. Give it a quick stir with a silicone spatula or wooden spoon and place the lid on the pot. Wait until the kernels start to pop and then, using hot pads, shake the pot vigorously, back and forth, until most of the kernels are popped. If you leave it on too long, the sugar will burn.
Remove kettle corn from heat, and pour the popcorn into a large heat-proof bowl. Add salt while it's still hot until desired saltiness.
Wash out the pot, dry it well, and repeat the process for the other colors.
*No food coloring needed for white popcorn. Each batch makes about 5 cups of popped corn (more or less).