yes but if you want to go red for instance you need to build it up
Permanent hair colour contains hydrogen peroxide whereas semi doesn't. Permanent colour changes the colour inside the hair. Semi doesn't. Permanent colour is permanent whereas semi only last 6-8 washes.
Yes, you can apply permanent hair color on top of semi-permanent hair color. Make sure that you do a deep conditioning treatment or hair masque before and after you color your hair.
black
Permanent colour doesn't wear off. Your natural colour grows out. If you were grey before you dyed your hair then the roots will grow out grey. Colour doesn't make your hair turn grey.
in the cortex
apply all over
yes
You cannot turn a permanent hair colour into a semi permanent hair colour. Permanent colours are made of small colour molecules that need a developer to create the chemical reaction required for the colour molecules to penetrate the hair shaft and tint to the desired shade. True Semi permanents are pretty much topical with mainly large colour molecules. (which is why you see the shade while the product is still in its original packaging) They require no developer as they sit ON TOP of the hair shaft with fewer smaller colour molecules that penetrate the cuticle.
A semi permanent colour is a colour that lasts 6-8 weeks. It lies just under the cuticle of the hair and this is why it washes out. (It doesn't enter into the hair or affect the internal structure of the hair).
If it isn't permanent colour, yes.
no sorry
Every week