(get ready for a somewhat lengthy post)
*By base colour I mean the colour your hair's bleached to before the semi-permanent dyes are applied over top.

When I had blue and or purple hair, my base colour was almost white, since that was what I was originally going for before I decided to add colour.

On the site, I've read that the best base for purples and blues is the lightest shade you can bleach your hair to, correct? And this makes sense to me.

However I went to get my hair cut and a woman there was inquiring about my hair. She seemed shocked that I had lightened my hair so much before adding purple and told me that yellow-blonde was the best base colour for unnatural colours because the dye adheres better.

My friend's mom, also a hairstylist says that very light bleached hair (like my almost white hair) has a lot of trouble holding on to colour too.

From what I've seen, colours on an extremely pale bases fade a lot more nicely than colours on yellow bases. But the hair pros say yellow is better for some reason?

Getting to platinum means an extra hour-long bleaching and obviously a lot more damage with stubborn black hair like mine. But gross brownish green hair is much less desirable than pastel colours when it comes to the fading period.

So which is the better base: yellow-blonde or platinum-blonde?

Wow, thanks for reading all that.

I don't know about that, alot of the things the "pros" say are wrong.
Besides, the makers of the dyes themselves even say almost-white hair is best.

Yeah that's a bunch of crap in my opinion.
The best base for any colour is pale yellow like the inside of a banana peel.

Yeah there's absolutely no way you can get a good blue with a yellow base. I'm nearly full-time blue. For me the colour always lasts several weeks and my hair has been bleached to that pale blonde shade. They may be referring to people who over process. There's a fine line. In my experience the hair stops holding colour when you try to bleach it white.
Yellow is a good base for reds but for blue or purple definitely not.

(Disclaimer: I have not confirmed this independently.)

I have had two hairdressers, who actually went to school to learn how dyes work chemically, tell me that there does need to be some natural color in the hair for dyes to work. They said that the colors in the dyes latch onto the natural pigments. Albino people apparently have trouble with this.

HOWEVER...

I believe this information refers only to *permanent* colors. Our semi-permanent colors, which are basically food coloring, don't work the same way at all. We're basically just trying to slap some colored goo into little openings on the hair shaft and hoping it sticks for a few weeks. Over-bleaching is only bad if you open up those gaps so much that the dye can fall right back out, which is what Jude was referring to.

if i'm dying my hair from a faded black dye, which is pretty much a gingery brown at the moment, to red what sort of colour do i need to bleach the section to?? also is it same to bleach the section to blonde and dye it red one after another or is this too much for my hair to handle??

If it's a good red you don't need to go very light although it'll probably help the longevity. I've dyed red over a very very brassy blonde in the past.

And as long as you're using a non-chemical dye (SFX, Directions etc...) it won't cause any additional damage after the bleach. I highly recommend SFX blood red or Directions Poppy Red, depending on what you can get hold of. A permanent red dye will cause damage because it'll involve a chemical reaction somewhere along the way.

being in germany ican get hold of any of those in any of my local shops. i have my hair dyed at da hairdressers cos i tried once and it totally messed up. i think they used schwarzkopf products.