Yes, it is OK and safe to apply semi permanent hair color on top of semi permanent hair color. The end result may be a little darker though.
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.
If the scalp is in good condition and was not irritated by the semi permanent color, it's OK to apply permanent color within 24 hours after initial color service.
You can but there is a chance that it can alter the results because of the semi permanent color. I would wait until it washes out before adding more.
Yes, it's fine to apply permanent color over semi permanent.
There is permanent hair color and semi-permanent hair color. _____________ Demi permanent and temporary are also known as non permanent hair color.
It is recommended that you wait 4-8 weeks between color treatments because the chemicals can damage your hair and you need to give your hair time to restore itself. You can apply the semi permanent hair color a couple weeks later, but make sure to condition your hair well and check with your stylist before taking that risk.
Yes you can. Highlight is a term for lightening the hair so you will have to use a lightning product to achieve the best results as permanent color will not lift the semi permanent color to the right level, but be sure to read the instructions and apply properly.
Of course you can. Semi permanent dye simply adds color to your hair. A permanent will actually cause your natural color to change. But remember this... color doesn't lift color. Therefore if your semi permanent hair color is darker than the permanent color you are going for---- it isn't going to work. You need to use a color remover before hand. And color removers are REALLY damaging to hair.