When you mix hair developer with a color or bleaching agent, it creates a chemical reaction that helps to lighten or darken your hair. Once you’re done using it, you need to properly dispose of the hair developer. Here are some tips on how to do so:
Pour the leftover hair developer down the drain. If there is a lot of residue left in the bowl or bottle, you can rinse it out with water first. Be sure to run hot water through the drain for a few minutes afterwards to help break down any chemicals that may be clinging to the sides of the pipes.
You can also pour the hair developer into a container and throw it away in the trash. Just be sure that the container is sealed tightly so that no one accidentally comes into contact with it.