About the acidic. I actually don't agree.

I've tried henna both with and without and the only difference was that my hair got dry with it. That's it. And I'm not the only one who's noticed that.

Acid is needed for henna tattoos and nails, to penetrate the skin and nails. I'm using henna on my nails, and there I notice a big difference with or without acid.

And henna will oxidize for a few days. After that it will not darken anymore, no matter what you used in the mix.

As for adding coffee and tea. I've tried it and it made no difference for me.

But if you still want to try adding stuff, I recommend something less drying, like hibiscus, applecider vinegar or black tea (not acidic).

I believe that your henna has faded because of the silver.

For learning more about henna I recommend our own NightShade's ebook https://www.nightblooming.com/produc...turally-ebook/