So, you tried a henna + indigo mix and you ended up with some purple or purplish-grey.
Indigo only makes auburns, browns & black when it is bound to henna. Henna binds to the hair, the indigo binds to the henna. Indigo is also only permanent when bound to henna. So, if there isn’t enough lawsone dye from the henna, there are going to be sections where indigo is bound directly to the hair, giving a streaked, uneven or odd colour.
Why did this happen? Here are the most likely causes:
1 – The henna wasn’t properly or fully dye released.
Did it sit long enough? (12 – 24 hours if mixed with lemon juice or vinegar at 20 Celsius). Was the henna paste covered air tight with plastic wrap? Did you add something to the paste that damages it? (oil, yogurt…).
2 – The henna didn’t have a high dye content anymore because it wasn’t stored in the freezer.
3 – Low quality (thus low dye content) henna bought off the shelf at a store was used with my high dye content indigo.
4 – The indigo wasn’t thoroughly mixed with the henna paste before application.
If you need to brush up on the best dye release techniques, go here: https://www.hennacanada.ca/HennaPaste-QuickRecipeGuide.htm
How to test for proper dye release:
A piece of paper towel can be placed over the plastic wrap that is against the henna paste. When that paper towel turns orange, dye release has begun. But that doesn’t mean that dye release is complete! Give it a few hours after this point if dye releasing with an acidic liquid (which released the most stable dye).
Do a skin patch test: a blob of henna paste on your skin for 1 minute should leave a *bright* orange stain. If it’s not a really bright stain, it’s not ready.
Morel of the story:
Be patient with your dye release (no matter how eager you are to henna your hair!) and quality is everything 😊