yes
Yes
yup
yes, however it has to be a darker shade. Semi permanent dye will never lighten your hair so you can use it to go darker but not lighter.
yes, however it has to be a darker shade. Semi permanent dye will never lighten your hair so you can use it to go darker but not lighter.
Semi permanent colour will wash out in 6-8 weeks.
yes, semi-permanent does not have harmful chemicals like permanent dye, I do it all the time.
yes
Do you mean pastel hair dye? It depends on if you use a permanent dye or a semi-permanent. Semi-permanent hair dyes will wash out and fade over time; permanent hair dyes will stay in the hair until you cut it or dye it another color.
The permanent color should cover the semi permanent one, if dark enough. But, yes, eventually the semi permanent color will fade away.
It'll cover them up.
Semi permanent refers to something that is not permanent but has a longer duration than temporary. In the context of hair dye or makeup, semi permanent products gradually fade over time with washing or exposure to the elements.
It won't remove it - the semi will need to wash out or fade over time. It will cover over it, but the end result may not be the one on the box as you will not be dying natural hair.