Can you explain if a permanent color can be applied over a semi-permanent color? If yes, how long do one need to wait before doing so? Similarly, is it possible to apply a semi-permanent color over a permanent hair color?
It’s always possible to apply Permanent color over semi-permanent color.
however, the time required between color applications solely depends on the condition of the hair in question. You could possibly be safe in applying a permanent color immediately following the application of a semi-permanent color, only if you are sure there are no existing signs of hair damage. Please make sure to take into consideration the base colors of the hair colors being used in order to prevent unwanted or weird color results, but usually applying permanent hair color over semi-permanent color should never cause you any problems.
This color process is for your original hair, if you want to try this on hair extensions it’s advisable to opt for unprocessed hair as processed hair may give weird end colors.
Is it possible to apply a semi-permanent color over a permanent hair color?.
Applying a semi-permanent color over a permanent hair color is actually a reverse process which is not universally a correct way to attempt. If the semi-permanent color is darker than the permanent color you can attempt to apply it over a permanent color. Basically, Semi-permanent color never provides any lifting action to the hair and therefore cannot be actually used to lighten the hair, irrespective of the hair been colored with permanent color or not.
The Permanent color formulas usually contain hydrogen peroxide developer of a sufficient strength to actually lift the color of the hair to which it is being applied before the color is actually deposited.
It’s advisable to avoid attempting this reverse process or if you want to experiment, you must first obtain professional advice from your hairstylist.