This is only my personal experience and dilemna, but it definitely has me puzzled and I can only reach out to other color artists to understand!
I am a natural red head, somewhere between a level seven and eight. For months now I have been using demi permanent color - Shades EQ and PM Shines. I have been using red, i.e. 5C, 7C, 6AA. Whatever I was feeling like at the time, they are all very similar. They fade out, but never completely.
I have decided I want to go blonde by summer. This should theoretically be very easy, as my hair is currently not very dark since I have done a soap cap. If it was just my natural red that would be even more of a piece of cake!
However, as I am trying to lift out the color (I have not used flat out lightener yet, but intend to after my hair has a break), it is turning an unnatural goldenrod fluorescent yellow, a yellow that I have never seen before, except for the last time I tried to lift out PM Shines 6R, and was inexperienced and attributed it to other factors.
My conclusion is that my hair has been stained this unGODly bright yellow color by the demi-permanent. A permanent color wouldn't do this, it would just lift out.
I intend to use an on the scalp lightener to take it up a few levels, and then use a high lift blue/violet base to try and knock out the yellow. This would theoretically work, but to me this shade goes beyond any theory that I've been taught!!
Anyone have any advice or similar experiences?