For best results of color, mehandi should be applied two days before the occassion especially in case of Marraige as it take two days for the color to develop into it's complete richness. Also, preferably do not wet the hands for the two days.
Many historical events say that Mehandi is the Art of Arabic Muslims who brought henna to India, where it has bloomed into its own exclusive art style. In Indian Mehandi, a person applies designs conventionally to a woman's hands and feet. For particularly auspicious occasions, men also apply Mehandi. The most auspicious occasion justifying Mehandi artwork is the Indian wedding, where both bride and bridegroom apply henna, as well as several members of the bridal party. Henna on any time symbolizes fruitfulness. At the wedding, henna artwork further represents the love between married .
Mehandi came into use because of its cooling healing effect in a hot weather conditions and in India, it was also a way for a bride and groom to get to know one another before an agreed Marriage. A variety of traditions underlie the use of Mehandi, including wedding games and legends. For example, the groom's name is usually written somewhere within the bride's Mehandi; if he cannot find his name within the complicated design, the bride is said to have the command in the marriage. Also, a dark Mehandi design for both bride and groom signifies that the two will have a strong relationship.

 
 
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