Why does the bottom half of my hair fades after about 2 washes after dying, but not the roots?

Info about my hair: naturally brown, thick curly (type 2c?), it's long/at my shoulder blades. I have hard water at home, but my hair is pretty healthy besides that because I don't do much heating to it. I usually dye my hair about 2-4 times a year with colors ranging from auburn to dark red brown (as well as some light brown/orange experimenting disasters). For the past year I haven't dyed my hair, before that it was an orange disaster and then I dyed it to my original color. My question: In the past month I had to dye my hair twice because the bottom half of my hair (older and maybe more damaged) faded so quickly (probably after like 2 washes) but my roots were still colored. My second times trying to color, I asked someone and they told me to use a protein filler. Ok, so I did that. My hair still faded!! Now I have dark purpley red cool roots and dark warm auburn ends :( I don't really want to be dying my hair all the time because I don't want to damage my hair further (because that's probably why my hair fades so quickly now), but my hair looks silly. So, what's going on with my hair, do you think? How can I solve my problem? Thanks!

3 Answers

It's probably more damaged from the repeated colorings, and more porous, and just can't hold the color as well. If you can hold off of the coloring for a while, that might be best.
using a sulfate shampoo. (sulfate strips hair)
It sounds like you bleached your natural color out of the hair on the ends and that is why you are getting such drastically different results. The ends are brighter/lighter/ fade faster, right? Sounds like the roots the dye color blends with the natural pigment. The best approach here is to dye a shade darker than your natural pigment color. I would recommend using a Vegetable dye cause you obviously have damage. Bigen is great for this. Henna too although go indigo/dark. This will get you a consistent, more natural shade throughout. Avoid chemical dyes.