A reaction would take place hours after, but that will still be the case if the tint has been in contact with the skin.
It doesn't need to be left on.
For example if you were tinting brows, the tint is only left on anywhere between 30 seconds & 2 mins then removed. An eyelash tint 10 mins. Reactions if they were to happen would be hours after. When the tint has been removed.
If the person has had a previous reaction the symptoms appear quicker the second/third time etc.
Xx
It doesn't need to be left on.
For example if you were tinting brows, the tint is only left on anywhere between 30 seconds & 2 mins then removed. An eyelash tint 10 mins. Reactions if they were to happen would be hours after. When the tint has been removed.
If the person has had a previous reaction the symptoms appear quicker the second/third time etc.
Xx