Once upon a time, once Hanuman ji felt hungry, he went to Mother Sita to take Kaleva. That day was Tuesday. At that time Mother Sita was applying vermilion on her head. Seeing her applying vermilion, Hanuman ji asked, what is the mother putting in her head? Sita ji said that this is vermilion. By applying this, the life of the owner (husband) is prolonged. It is a symbol of married women. It is lucky for married women. Whoever applies this vermilion, its owner is happy. If I apply vermilion, then Shri Ram ji is pleased.
Then Hanuman ji thought that if Shri Ram ji is pleased by applying vermilion with a finger, and his life increases, then why not I should make Shri Ram ji immortal by applying vermilion all over my body. He applied vermilion all over his body and reached the meeting of Shri Ram ji. Seeing him like this, everyone started laughing, even Shri Ramji started smiling.
Lord was very pleased because of this behavior of his and Shri Ram ji got him done and the person who will offer vermilion on Hanuman ji on Tuesday and Saturday will get my happiness and all his wishes will be fulfilled. Since then till date, vermilion and jasmine oil is offered on Hanuman ji. If a person offers jasmine oil and vermilion to Hanuman ji on Tuesday and Saturday with devotion, all his wishes are fulfilled. And Lord Shri Ram ji is pleased with that person. It is also called chola plating.