Why do our hands give colouring after appling mehandi? what is the chemical reaction going on?

Answer:
http://www.shubhlagan.in/features_mehand...It is just a stain that sets into the skin, not a chemical reaction that causes the color to remain on your skin.
You do use lemon juice to set the dye in the skin to make it last longer, so the use of a mild acidic setting agent could be considered a chemical reaction.

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