How do I have my coon tails not bleed?

Okay so I’m technically not allowed to dye my hair so I have to get crafty and make my own at home hair dye, the dye that I created consists of blue food coloring and a deep conditioner. I apply it as a coin tail on my hair and let it wait for about 2 hours to make sure it wouldn’t bleed and when the time came I washed it out it with cold water going strip by strip and then when I went to look in the mirror the color was there but it just looked like a blue streak in my hair and I think I did what I was supposed to but it keeps on bleeding out what do I do now??!!