Do you mean a henna gloss?
Fia’s Henna Gloss- For slighter color change and deep conditioning.
2-3 TB henna powder
Enough water to mix a smooth paste
Your favorite conditioner or plain, unsweetened yogurt
Mix the henna powder with water to a smooth paste and let this stand until you see dye release. Mix the henna paste with either your favorite conditioner or plain yogurt. Apply to dry or damp hair, wrap in plastic wrap, and leave on for as long as you wish. Rinse as you'd rinse out a regular conditioner. This one is easy to apply and rinse, as it's basically conditioner or yogurt with just a hint of henna dye in it. It's good as either a color refresher in between regular henna applications or if you only wish to have a very subtle color change. It will give reddish hints on blonde and light brown hair. You may see some reddish highlights on medium brown, but probably not too much. On dark brown/black hair you'll only get the conditioning benefits from the conditioner/henna.
I pulled that from the henna article in my siggy. Worth a read if you haven't already