I did a reTi a few days ago. I can't really remember how long it took as I had so many interruptions. If I condense it all , it probably took 4+ hrs. So I decided to do another henna. This time I crushed the henna in a mortar&pestle before I put in a glass bowl with boiling water, over a pan with boiling water. I mixed a little caca maroon (red)with caca brun(brown). I'm now sitting with plastic covering over my head, but it just occured to me that I ahould have applied the henna to my hairline 1st. Instead I started from the back when the mixture was quite hot. By the time I got to the front it had gone cold and henna colours better if it's warm/hot. Anyway, I'll update when I wash it out.