From the longhaircommunity:

 

 

"I just wanted to let everyone know about a new method that I discovered for upping my red factor between hennas. I wanted redder hair, but as I just henna'd, and my new batch hasn't even arrived yet, I was trying to figure out what else I could use. Here's what I used, and I can tell you that 3 full washed later, I am definite that this red addition is a permanent as the Henna

1 cup aloe vera gel
2 tblsp red bush tea (finely ground)
3 tblsp paprika

I started by heating the aloe vera gel in a small pan on the stove. Then I added the tea (it's ground fine, it just looks like a bunch of small twigs at this point) After about 5 minutes of simmering on low, the gel definitely had a red/orange tinge. Then I slowly stirred in the paprika. After simmering another 10 minutes, the whole mess was very red and how, looking a little thinner. I scooped it in a bowl and put it in my freezer to cool down and thicken up. 20 minutes later, I took it from the bowl and applied it to ly head, just like henna. (Only I forgot to wear gloves, and it stained my hands slightly, so nest time I will be remembering gloves)
Once everything was applied, I put on a shower cap, then blasted my head for 3-4 minutes with my blow dryer. once it was nice and hot, I put a towel turbie on. I wore this for about 2 hours, stopping every 30 minutes to add another blast of heat. I finally wahed with a lot of conditioner (the tea twigs do not come out that easy!)
The final result is even more red that is long lasting. I'm excited I've found a way to enhance my color between glossings!"

 

 

I'm thinking of trying this method but with black tea instead to darken my hair a bit. Don't know if it will work though.