I used Deewal hair color black herbal for the first time and 2 steps to be followed for hair coloring,it takes 1 hour each, I think 1st step is to prevent allergy or other similar effects and 2nd one which gives colour to the hair. no allergy, swelling or irritation problem faced by me as am allergic to the hair colours .I will suggest for sensitive skin users, if u are looking for allergy free hair colour product,before using it, take the preliminary allergy test first. because I have...