Here's why:
* Tri-iodine is not a hair dye. It's a chemical compound with antiseptic and disinfectant properties, typically used in medical settings.
* It can be dangerous to apply to the scalp and hair. Tri-iodine can cause irritation, burns, and allergic reactions.
* There's no evidence that it can darken hair.
If you're looking to darken your gray hair, it's best to consult a professional hairdresser or use commercially available hair dyes.